Daily and annual course. Daily and annual temperature variation

The daily course of air temperature is the change in air temperature during the day. In general, it reflects the course of the temperature of the earth's surface, but the moments of the onset of maxima and minima are somewhat late: the maximum occurs at 2 pm, the minimum after sunrise.

Daily amplitude of air temperature- the difference between the maximum and minimum air temperature during the day. It is higher on land than over the ocean, decreases when moving to high latitudes, and increases in places with bare soil. The highest amplitude in tropical deserts is up to 40º C. The value of the daily amplitude of air temperature is one of the indicators of the continentality of the climate. In deserts, it is much greater than in areas with a maritime climate.

Annual variation of air temperature(change in the average monthly temperature during the year) is determined primarily by the latitude of the place. Annual amplitude of air temperature- the difference between the maximum and minimum average monthly temperature.

The geographical distribution of air temperature is shown using isotherms- lines connecting points on the map with the same temperature. The distribution of air temperature is zonal, the annual isotherms as a whole have a sublatitudinal strike and correspond to the annual distribution of the radiation balance (Fig. 10, 11).

On average over the year, the warmest parallel is 10º N. with a temperature of +27º C is thermal equator. In summer, the thermal equator shifts to 20º N, in winter it approaches the equator by 5º N.

Rice. 10. Distribution of average air temperature in July

Rice. 11. Distribution of average air temperature in January

The shift of the thermal equator in the SP is explained by the fact that in the SP the land area located at low latitudes is larger compared to the SP, and it has higher temperatures during the year.

Heat on the earth's surface is distributed zonal-regional. In addition to geographic latitude, the distribution of temperatures on Earth is influenced by the nature of the distribution of land and sea, relief, elevation above sea level, sea and air currents.

The latitudinal distribution of annual isotherms is disturbed by warm and cold currents. In the temperate latitudes of the NP, the western shores, washed by warm currents, are warmer than the eastern shores, along which cold currents pass. Consequently, the isotherms at the western coasts are bent towards the pole, at the eastern coasts - towards the equator.

The average annual temperature of SP is +15.2ºС, and SP is +13.2ºС. In SP, minimum temperatures are much lower; at the stations "Sovetskaya" and "Vostok" the temperature was -89.2º С (the absolute minimum of SP). The minimum temperature in cloudless weather in Antarctica can drop to -93º C. The highest temperatures are observed in the deserts of the tropical zone: +58º C in Tripoli, +56.7º C in California in Death Valley.

Maps give an idea of ​​how continents and oceans affect the distribution of temperatures. isonomal(isonomals are lines connecting points with the same temperature anomalies). Anomalies are deviations of actual temperatures from mid-latitude ones. Anomalies are positive and negative. Positive anomalies are observed in summer over heated continents. Over Asia, temperatures are 4º C higher than the mid-latitude ones. In winter, positive anomalies are located above warm currents (above the warm North Atlantic Current off the coast of Scandinavia, the temperature is 28º C above the norm). Negative anomalies are pronounced in winter over chilled continents and in summer over cold currents. For example, in Oymyakon in winter the temperature is 22º C below the norm.

The following thermal zones are distinguished on Earth (isotherms are taken beyond the boundaries of thermal zones):

1. Hot, is limited in each hemisphere by an annual isotherm of + 20º С, passing near 30º s. sh. and y.sh.

2. Two temperate belts, which in each hemisphere lie between the annual isotherm + 20º C and + 10º C of the warmest month (respectively, July or January).

3. two cold belts, the boundary passes along the 0º C isotherm of the warmest month. Sometimes there are regions eternal frost, which are located around the poles (Shubaev, 1977).

In this way:

1. The only source of energy that is of practical importance for the course of exogenous processes in GO is the Sun. Heat from the Sun enters the world space in the form of radiant energy, which then, absorbed by the Earth, turns into thermal energy.

2. The sunbeam on its way is subjected to numerous influences (scattering, absorption, reflection) from the various elements of the medium it penetrates and the surfaces on which it falls.

3. The distribution of solar radiation is influenced by: the distance between the earth and the Sun, the angle of incidence of the sun's rays, the shape of the Earth (predetermines the decrease in the intensity of radiation from the equator to the poles). This is the main reason for the allocation of thermal zones and, consequently, the reason for the existence of climatic zones.

4. The influence of the latitude of the area on the distribution of heat is corrected by a number of factors: relief; distribution of land and sea; influence of cold and warm sea currents; atmospheric circulation.

5. The distribution of solar heat is further complicated by the fact that the regularities and features of the vertical distribution are superimposed on the regularities of the horizontal (along the earth's surface) distribution of radiation and heat.

General circulation of the atmosphere

Air currents of different scales are formed in the atmosphere. They can cover the entire globe, and in height - the troposphere and lower stratosphere, or affect only a limited area of ​​the territory. Air currents ensure the redistribution of heat and moisture between low and high latitudes and carry moisture deep into the continent. According to the distribution area, winds of the general atmospheric circulation (GCA), winds of cyclones and anticyclones, and local winds are distinguished. The main reason for the formation of winds is the uneven distribution of pressure over the surface of the planet.

Pressure. normal atmospheric pressure- the weight of an atmospheric column with a cross section of 1 cm 2 at ocean level at 0ºС at 45º latitude. It is balanced by a mercury column of 760 mm. Normal atmospheric pressure is 760 mm Hg or 1013.25 mb. Pressure in SI is measured in pascals (Pa): 1 mb = 100 Pa. Normal atmospheric pressure is 1013.25 hPa. The lowest pressure ever observed on Earth (at sea level), 914 hPa (686 mm); the highest is 1067.1 hPa (801 mm).

The pressure decreases with height, as the thickness of the overlying layer of the atmosphere decreases. The distance in meters that one must rise or fall in order for the atmospheric pressure to change by 1 hPa is called pressure stage. The baric step at a height of 0 to 1 km is 10.5 m, from 1 to 2 km - 11.9 m, 2-3 km - 13.5 m. The value of the baric step depends on temperature: with increasing temperature, it increases by 0 ,four %. In warm air, the baric step is greater, therefore, warm regions of the atmosphere in high layers have more pressure than cold ones. The reciprocal of the baric step is called vertical baric gradient is the change in pressure per unit of distance (100 m is taken as a unit of distance).

Pressure changes as a result of the movement of air - its outflow from one place and inflow to another. Air movement is due to a change in air density (g / cm 3), resulting from uneven heating of the underlying surface. Over an equally heated surface, the pressure decreases uniformly with height, and isobaric surfaces(surfaces drawn through points with the same pressure) are parallel to each other and the underlying surface. In the region of increased pressure, the isobaric surfaces are convex upwards, in the regions of reduced pressure, downwards. On the earth's surface, pressure is shown using isobar Lines connecting points of equal pressure. The distribution of atmospheric pressure at ocean level, depicted using isobars, is called baric relief.

The pressure of the atmosphere on the earth's surface, its distribution in space and change in time is called baric field. The areas of high and low pressure into which the baric field is divided are called pressure systems.

Closed baric systems include baric maxima (a system of closed isobars with an increased pressure in the center) and minima (a system of closed isobars with a reduced pressure in the center), open baric systems include a baric crest (a band of increased pressure from a baric maximum inside a reduced pressure field), a trough ( low pressure band from the baric minimum inside the high pressure field) and a saddle (an open system of isobars between two baric maxima and two minima). In the literature, there is the concept of "baric depression" - a belt of low pressure, inside which there can be closed baric minima.

The pressure on the earth's surface is distributed zonally. At the equator during the year there is a belt of low pressure - equatorial depression(less than 1015 hPa) . In July, it moves to the Northern Hemisphere at 15–20º N, in December - to the Southern Hemisphere, at 5º S. In tropical latitudes (between 35º and 20º of both hemispheres), the pressure during the year is increased - tropical (subtropical) baric highs(more than 1020 hPa). In winter, a continuous belt of high pressure appears over the oceans and land (Azores and Hawaiian - SP; South Atlantic, South Pacific and South Indian - SP). In summer, increased pressure persists only over the oceans, over land the pressure decreases, thermal depressions occur (Iran-Tara minimum - 994 hPa). In temperate latitudes, the SP forms a continuous belt in summer reduced pressure, however, the baric field is dissymmetric: in the South Pacific, in temperate and subpolar latitudes, there is a band of low pressure above the water surface throughout the year (Antarctic minimum - up to 984 hPa); in the SP, due to the alternation of continental and oceanic sectors, baric minima are expressed only over the oceans (Icelandic and Aleutian - pressure in January 998 hPa); in winter, baric maxima appear over the continents due to strong cooling of the surface. In polar latitudes, over the ice sheets of Antarctica and Greenland, the pressure during the year elevated- 1000 hPa (low temperatures - cold and heavy air) (Fig. 12, 13).

Stable areas of high and low pressure, into which the baric field breaks up near the surface of the earth, are called centers of action of the atmosphere. There are territories over which the pressure remains constant throughout the year (pressure systems of the same type predominate, either maxima or minima); permanent centers of action of the atmosphere:

– equatorial depression;

– Aleutian Low (temperate latitudes of the SP);

– Icelandic low (temperate latitudes of the SP);

- low pressure zone of temperate latitudes SP (Antarctic low pressure belt);

– subtropical zones of high pressure SP:

Azores High (North Atlantic High)

Hawaiian High (North Pacific High)

– subtropical zones of high pressure SP:

South Pacific High (southwest of South America)

South Atlantic High (St. Helena anticyclone)

South Indian High (Mauritius anticyclone)

– Antarctic maximum;

– Greenland maximum.

Seasonal pressure systems are formed in the event that the pressure seasonally changes sign to the opposite: in place of the baric maximum, a baric minimum occurs and vice versa. Seasonal pressure systems include:

- the summer South Asian minimum with a center near 30º N. latitude. (997 hPa)

– winter Asian maximum centered over Mongolia (1036 hPa)

– summer Mexican low (North American depression) – 1012 hPa

– winter North American and Canadian highs (1020 hPa)

– summer (January) depressions over Australia, South America and South Africa give way in winter to Australian, South American and South African anticyclones.

Wind. Horizontal baric gradient. The movement of air in a horizontal direction is called wind. The wind is characterized by speed, strength and direction. Wind speed - the distance that air travels per unit of time (m / s, km / h). Wind force - the pressure exerted by air on a site of 1 m 2 located perpendicular to the movement. The strength of the wind is determined in kg / m 2 or in points on the Beaufort scale (0 points - calm, 12 - hurricane).

The wind speed is determined horizontal baric gradient– change in pressure (pressure drop by 1 hPa) per unit distance (100 km) in the direction of decreasing pressure and perpendicular to the isobars. In addition to the barometric gradient, the wind is affected by the rotation of the Earth (Coriolis force), centrifugal force and friction.

The Coriolis force deflects the wind to the right (in SP to the left) of the direction of the gradient. Centrifugal force acts on the wind in closed baric systems - cyclones and anticyclones. It is directed along the radius of curvature of the trajectory towards its convexity. The force of air friction on the earth's surface always reduces the wind speed. Friction affects the lower, 1000-meter layer, called friction layer. The movement of air in the absence of friction is called gradient wind. Gradient wind blowing along parallel rectilinear isobars is called geostrophic, along curvilinear closed isobars – geocyclostrophic. A visual representation of the frequency of occurrence of winds in certain directions is given by the diagram "Rose of Wind".

In accordance with the baric relief, the following wind zones exist:

- equatorial belt of calm (winds are relatively rare, since ascending movements of strongly heated air dominate);

- zones of trade winds of the northern and southern hemispheres;

- areas of calm in the anticyclones of the subtropical high-pressure belt (the reason is the dominance of descending air movements);

- in the middle latitudes of both hemispheres - zones of predominance of westerly winds;

– in circumpolar spaces, winds blow from the poles towards baric depressions of middle latitudes, i.e. winds with an easterly component are common here.

General atmospheric circulation (GCA)- a system of air flows on a planetary scale, covering the entire globe, troposphere and lower stratosphere. Released in atmospheric circulation zonal and meridional transfers. The zonal transfers developing mainly in the sublatitudinal direction include:

- western transfer, which dominates the entire planet in the upper troposphere and lower stratosphere;

- in the lower troposphere, in polar latitudes - easterly winds; in temperate latitudes - westerly winds, in tropical and equatorial latitudes - easterly ones (Fig. 14).

from the pole to the equator.

In fact, the air at the equator in the surface layer of the atmosphere is very warm. Warm and humid air rises, its volume increases, and high pressure arises in the upper troposphere. At the poles, due to the strong cooling of the surface layers of the atmosphere, the air is compressed, its volume decreases, and at the top the pressure drops. Consequently, in the upper layers of the troposphere, there is a flow of air from the equator to the poles. Due to this, the mass of air at the equator, and hence the pressure at the underlying surface, decreases, and increases at the poles. In the surface layer, movement begins from the poles to the equator. Conclusion: solar radiation forms the meridional component of the OCA.

On a homogeneous rotating Earth, the Coriolis force also acts. At the top, the Coriolis force deflects the flow in the SP to the right of the direction of motion, i.e. from west to east. In the SP, the air movement deviates to the left, i.e. again from west to east. Therefore, at the top (in the upper troposphere and lower stratosphere, in the altitude range from 10 to 20 km, the pressure decreases from the equator to the poles), a western transfer is noted, it is noted for the entire Earth as a whole. In general, air movement occurs around the poles. Consequently, the Coriolis force forms the zonal transport of the OCA.

Below the underlying surface, the movement is more complex; its division into continents and oceans. A complex pattern of major air currents is formed. From subtropical high-pressure belts, air currents flow to the equatorial depression and to temperate latitudes. In the first case, easterly winds of tropical-equatorial latitudes are formed. Over the oceans, thanks to constant baric maxima, they exist all year round - trade winds- winds of the equatorial peripheries of subtropical maxima, constantly blowing only over the oceans; over land, they are not traced everywhere and not always (breaks are caused by the weakening of subtropical anticyclones due to strong heating and movement of the equatorial depression to these latitudes). In the SP, the trade winds have a northeasterly direction, in the SP - southeasterly. The trade winds of both hemispheres converge near the equator. In the region of their convergence (the intratropical convergence zone), strong ascending air currents arise, cumulus clouds form, and showers fall.

The wind flow going to temperate latitudes from the tropical zone of high pressure forms westerly winds of temperate latitudes. They intensify in winter, as baric minima grow over the ocean in temperate latitudes, the baric gradient between baric minima over the oceans and baric maxima over land increases, therefore, the strength of the winds also increases. In SP the direction of winds is south-west, in SP - north-west. Sometimes these winds are called anti-trade winds, but they are not genetically related to the trade winds, but are part of the planetary westerly transport.

Eastern transfer. The prevailing winds in the polar latitudes are northeasterly in the SP and southeasterly in the SF. The air moves from the polar areas of high pressure towards the low pressure zone of temperate latitudes. The eastern transport is also represented by the trade winds of tropical latitudes. Near the equator, eastward transport covers almost the entire troposphere, and there is no westward transport here.

Analysis of the latitudes of the main parts of the OCA allows us to distinguish three zonal open links:

- polar: easterly winds blow in the lower troposphere, above - westerly transport;

– moderate link: in the lower and upper troposphere – westerly winds;

- tropical link: in the lower troposphere - easterly winds, above - westerly transfer.

The tropical link of the circulation was called the Hadley cell (the author of the earliest OCA scheme, 1735), the temperate link - the Frerel cell (an American meteorologist). At present, the existence of cells is questioned (S.P. Khromov, B.L. Dzerdievsky), however, mention of them remains in the literature.

Jet currents are hurricane-force winds blowing over frontal zones in the upper troposphere and lower stratosphere. They are especially pronounced above the polar fronts, the wind speed reaches 300–400 km/h due to large pressure gradients and rarefied atmosphere.

Meridional transfers complicate the OCA system and provide interlatitudinal exchange of heat and moisture. The main meridional transports are monsoons- seasonal winds that change direction in summer and winter to the opposite. There are tropical and extratropical monsoons.

tropical monsoons arise due to thermal differences between the summer and winter hemispheres, the distribution of land and sea only enhances, complicates or stabilizes this phenomenon. In January, an almost uninterrupted chain of anticyclones is located in the SP: permanent subtropical ones over the oceans, and seasonal ones over the continents. At the same time, an equatorial depression shifted there lies in the SP. As a result, air is transferred from the SP to the SP. In July, with an inverse ratio of baric systems, air is transferred across the equator from the SP to the SP. Thus, tropical monsoons are nothing but trade winds, which in a certain band close to the equator acquire a different property - a seasonal change in the general direction. Tropical monsoons exchange air between hemispheres, and on between land and sea, especially since in the tropics the thermal contrast between land and sea is generally small. The entire area of ​​distribution of tropical monsoons lies between 20º N.S. and 15º S (tropical Africa north of the equator, eastern Africa south of the equator; southern Arabia; Indian Ocean to Madagascar in the west and to northern Australia in the east; Hindustan, Indochina, Indonesia (without Sumatra), East China; in South America - Colombia ). For example, the monsoon current, which originates in an anticyclone over northern Australia and goes to Asia, is directed, in essence, from one continent to another; the ocean in this case serves only as an intermediate territory. The monsoons in Africa are the exchange of air between the dry land of the same continent lying in different hemispheres, and over a part of the Pacific Ocean the monsoon blows from the oceanic surface of one hemisphere to the oceanic surface of the other.

In education extratropical monsoons The leading role is played by the thermal contrast between land and sea. Here monsoons occur between seasonal anticyclones and depressions, some of which lie on the mainland and others on the ocean. Thus, the winter monsoons in the Far East are a consequence of the interaction of the anticyclone over Asia (with its center in Mongolia) and the permanent Aleutian depression; summer - a consequence of an anticyclone over the northern part of the Pacific Ocean and a depression over the extratropical part of the Asian continent.

Extratropical monsoons are best expressed in the Far East (including Kamchatka), the Sea of ​​Okhotsk, Japan, Alaska, and the coast of the Arctic Ocean.

One of the main conditions for the manifestation of monsoon circulation is the absence of cyclonic activity (there is no monsoon circulation over Europe and North America due to the intensity of cyclonic activity, it is “washed away” by western transport).

Winds of cyclones and anticyclones. In the atmosphere, when two air masses with different characteristics meet, large atmospheric vortices constantly arise - cyclones and anticyclones. They greatly complicate the OCA scheme.

Cyclone- a flat ascending atmospheric vortex, which manifests itself near the earth's surface as an area of ​​low pressure, with a system of winds from the periphery to the center counterclockwise in the SP and clockwise in the SP.

Anticyclone- a flat descending atmospheric vortex, which manifests itself near the earth's surface as an area of ​​\u200b\u200bhigh pressure, with a system of winds from the center to the periphery clockwise in the SP and counterclockwise in the SP.

The eddies are flat, since their horizontal dimensions are thousands of square kilometers, while their vertical dimensions are 15–20 km. In the center of the cyclone, ascending air currents are observed, in the anticyclone - descending ones.

Cyclones are divided into frontal, central, tropical and thermal depressions.

Frontal cyclones are formed on the Arctic and Polar fronts: on the Arctic front of the North Atlantic (near the eastern coast of North America and near Iceland), on the Arctic front in the northern part of the Pacific Ocean (near the eastern coast of Asia and near the Aleutian Islands). Cyclones usually exist for several days, moving from west to east at a speed of about 20-30 km/h. A series of cyclones appears at the front, in a series of three or four cyclones. Each next cyclone is at a younger stage of development and moves faster. Cyclones overtake each other, close, forming central cyclones- the second type of cyclone. Due to the inactive central cyclones, an area of ​​low pressure is maintained over the oceans and in temperate latitudes.

Cyclones originating in the north of the Atlantic Ocean are moving towards Western Europe. Most often they pass through the UK, the Baltic Sea, St. Petersburg and on to the Urals and Western Siberia or through Scandinavia, the Kola Peninsula and on to either Spitsbergen or the northern outskirts of Asia.

North Pacific cyclones go to northwest America, as well as northeast Asia.

Tropical cyclones formed on tropical fronts most often between 5º and 20º N. and yu. sh. They occur over the oceans at the end of summer and autumn, when the water is heated to a temperature of 27–28º C. A powerful rise in warm and humid air leads to the release of a huge amount of heat during condensation, which determines the kinetic energy of the cyclone and low pressure in the center. Cyclones move from east to west along the equatorial periphery of permanent baric maxima on the oceans. If a tropical cyclone reaches temperate latitudes, it expands, loses energy and, as an extratropical cyclone, begins to move from west to east. The speed of the cyclone itself is small (20–30 km/h), but the winds in it can have a speed of up to 100 m/s (Fig. 15).

Rice. 15. Distribution of tropical cyclones

The main areas of occurrence of tropical cyclones: the east coast of Asia, the northern coast of Australia, the Arabian Sea, the Bay of Bengal; Caribbean Sea and Gulf of Mexico. On average, there are about 70 tropical cyclones per year with wind speeds of more than 20 m/s. Tropical cyclones are called typhoons in the Pacific, hurricanes in the Atlantic, and willy-willies off the coast of Australia.

Thermal depressions arise on land due to the strong overheating of the surface area, the rise and spread of air above it. As a result, an area of ​​low pressure is formed near the underlying surface.

Anticyclones are subdivided into frontal, subtropical anticyclones of dynamic origin and stationary ones.

In temperate latitudes, in cold air, frontal anticyclones, which move in series from west to east at a speed of 20–30 km/h. The last final anticyclone reaches the subtropics, stabilizes and forms subtropical anticyclone of dynamic origin. These include permanent baric maxima on the oceans. Stationary anticyclone occurs over land in winter as a result of a strong cooling of the surface area.

Anticyclones originate and hold steadily over the cold surfaces of the Eastern Arctic, Antarctica, and in winter Eastern Siberia. When arctic air breaks from the north in winter, the anticyclone sets up over all of Eastern Europe, and sometimes captures Western and Southern Europe.

Each cyclone is followed and moves at the same speed by an anticyclone, which includes any cyclonic series. When moving from west to east, cyclones deviate to the north, and anticyclones deviate to the south in the SP. The reason for the deviations is explained by the influence of the Coriolis force. Consequently, cyclones begin to move to the northeast, and anticyclones to the southeast. Due to the winds of cyclones and anticyclones, there is an exchange of heat and moisture between latitudes. In areas of high pressure, air flows from top to bottom predominate - the air is dry, there are no clouds; in areas of low pressure - from bottom to top - clouds form, precipitation falls. The introduction of warm air masses is called "heat waves". The movement of tropical air masses to temperate latitudes causes drought in summer and strong thaws in winter. The introduction of arctic air masses into temperate latitudes - "cold waves" - causes cooling.

local winds- winds that occur in limited areas of the territory as a result of the influence of local causes. The local winds of thermal origin include breezes, mountain-valley winds, the influence of the relief causes the formation of foehns and boron.

breezes occur on the shores of oceans, seas, lakes, where there are large daily temperature fluctuations. Urban breezes have formed in major cities. In the daytime, when the land is heated more strongly, an upward movement of air occurs above it and its outflow from above towards the colder one. In the surface layers, the wind blows towards the land, this is a daytime (sea) breeze. Night (coastal) breeze occurs at night. When land cools more than water, and in the surface layer of air, the wind blows from land to sea. Sea breezes are more pronounced, their speed is 7 m/s, the propagation band is up to 100 km.

Mountain valley winds form the winds of the slopes and the actual mountain-valley winds and have a daily periodicity. Slope winds are the result of different heating of the slope surface and air at the same height. During the day, the air on the slope heats up more and the wind blows up the slope, at night the slope also cools more and the wind begins to blow down the slope. Actually mountain-valley winds are caused by the fact that the air in the mountain valley heats up and cools more than at the same height on the neighboring plain. At night the wind blows towards the plains, during the day - towards the mountains. The slope facing the wind is called the windward slope, and the opposite slope is called the leeward slope.

hair dryer- a warm dry wind from high mountains, often covered with glaciers. It arises due to adiabatic cooling of air on the windward slope and adiabatic heating - on the leeward slope. The most typical foehn occurs when the OCA air current crosses a mountain range. More often meets anticyclone foehn, it is formed if there is an anticyclone over a mountainous country. Hair dryers are most frequent in the transitional seasons, their duration is several days (in the Alps, there are 125 days with hair dryers a year). In the Tien Shan mountains, such winds are called castek, in Central Asia - garmsil, in the Rocky Mountains - chinook. Hair dryers cause gardens to bloom early, snow to melt.

Bora- a cold wind blowing from low mountains towards the warm sea. In Novorossiysk it is called nord-ost, on the Absheron peninsula - nord, on Baikal - sarma, in the Rhone Valley (France) - mistral. Bora occurs in winter, when an area of ​​high pressure forms in front of the ridge, on the plain, where cold air forms. Having crossed a low ridge, cold air rushes at high speed towards a warm bay, where the pressure is low, the speed can reach 30 m/s, the air temperature drops sharply to -5ºС.

Small scale eddies are tornadoes and blood clots (tornado). Vortices over the sea are called tornadoes, over land - blood clots. Tornadoes and blood clots usually originate in the same places as tropical cyclones, in a hot, humid climate. The main source of energy is the condensation of water vapor, in which energy is released. A large number of tornadoes in the United States is due to the arrival of moist warm air from the Gulf of Mexico. The whirlwind moves at a speed of 30–40 km/h, but the wind speed in it reaches 100 m/s. Thrombi usually occur singly, whirlwinds - in series. In 1981, 105 tornadoes formed off the coast of England within five hours.

The concept of air masses (VM). An analysis of the above shows that the troposphere cannot be physically homogeneous in all its parts. It is divided, without ceasing to be one and whole, into air masses– large volumes of air in the troposphere and lower stratosphere, which have relatively uniform properties and move as a whole in one of the OCA streams. The dimensions of the VM are comparable to parts of the continents, the length is thousands of kilometers, and the thickness is 22–25 km. The territories over which VMs are formed are called formation centers. They must have a uniform underlying surface (land or sea), certain thermal conditions and the time required for their formation. Similar conditions exist in baric maxima over oceans, in seasonal maxima over land.

VM has typical properties only in the center of formation; when moving, it transforms, acquiring new properties. The arrival of certain VMs causes abrupt changes in the weather of a non-periodic nature. In relation to the temperature of the underlying surface, VMs are divided into warm and cold. A warm VM moves to a cold underlying surface, it brings warming, but cools itself. Cold VM comes to the warm underlying surface and brings cooling. According to the formation conditions, VMs are divided into four types: equatorial, tropical, polar (air of temperate latitudes) and arctic (Antarctic). In each type, two subtypes are distinguished - marine and continental. For continental subtype, formed over the continents, is characterized by a large temperature range and low humidity. marine subtype It is formed over the oceans, therefore, its relative and absolute humidity are increased, the temperature amplitudes are much less than continental ones.

Equatorial VMs are formed in low latitudes, characterized by high temperatures and high relative and absolute humidity. These properties are preserved both over land and over the sea.

Tropical VM are formed in tropical latitudes, the temperature during the year does not fall below 20º C, the relative humidity is low. Allocate:

– continental HTMs that form over the continents of tropical latitudes in tropical baric maxima - over the Sahara, Arabia, Thar, Kalahari, and in summer in the subtropics and even in the south of temperate latitudes - in southern Europe, in Central Asia and Kazakhstan, in Mongolia and northern China;

– marine HCMs that form over tropical water areas – in the Azores and Hawaiian highs; characterized by high temperature and moisture content, but low relative humidity.

Polar VMs, or air of temperate latitudes, are formed in temperate latitudes (in anticyclones of temperate latitudes from arctic VMs and air that came from the tropics). Temperatures are negative in winter, positive in summer, the annual temperature amplitude is significant, absolute humidity increases in summer and decreases in winter, relative humidity is average. Allocate:

– continental air of temperate latitudes (CHC), which is formed over the vast surfaces of continents of temperate latitudes, is strongly chilled and stable in winter, the weather in it is clear with severe frosts; in summer it gets very warm, ascending currents arise in it;

Air temperature and diurnal temperature variation

Target: To form an idea of ​​the distribution of heat on the surface of the Earth, the average daily temperature, the amplitude of temperature fluctuations (daily, annual).

Equipment: thermometer textbook.

During the classes.

I .Organizing time. Rapport.

II . Checking homework

Test.

Which gas is predominant in the atmosphere:

a) oxygen; b) hydrogen; c) carbon dioxide; d) nitrogen.

Which layer of the atmosphere contains most of the air?

At what latitudes is the troposphere thicker?

a) above the equator b) in polar latitudes; c) in temperate latitudes.

What layer of the atmosphere is above the troposphere?

a) exosphere; b) stratosphere; c) mesosphere.

In which layer does the weather change occur:

a) in the stratosphere b) in the troposphere; c) in the upper atmosphere.III . Learning new material. How is the air heated?

How much of the solar energy do you think will heat the air in the troposphere?

Describe how temperature changes in the troposphere and with height. Why is the temperature dropping?

Reveal patterns :

The sun's rays pass through the atmosphere without heating it.

The sun's rays heat the earth's surface

Atmospheric air is heated by the Earth's surface

Air temperature decreases with altitude. For every km, the temperature drops by 6°C.

What is the reason for the unequal heating of air during the day? Look at the picture on the slide, try to formulate a pattern.

regularity : the higher the Sun above the horizon, the greater the angle of incidence of the sun's rays, therefore, the surface of the Earth warms up better, and the air from it.

The daily course of air temperature.

At what time of the day is the temperature the highest and lowest? Explain.

How does temperature change throughout the year?

Think about why the warmest and coldest months are not June and December, when the sun's rays have the largest and smallest angles of incidence on the earth's surface.

Air temperature - the degree of air heating, determined with a thermometer.

Air temperature is one of the most important characteristics of weather and climate.

The temperature of air, as well as soil and water in most countries is expressed in degrees of the international temperature scale, or scaleCelsius (FROM). Zero of this scale falls on the temperature at which ice melts, and +100 ˚С - on the boiling point of water. However, in the United States and a number of other countries, the scale is still used not only in everyday life, but also in meteorology.Fahrenheit (F). In this scale, the interval between the melting points of ice and the boiling point of water is divided by 180˚, with the melting point of ice assigned a value of +32 ˚F. Zero Celsius corresponds to +32 ˚F, and +100 ˚С = +212 ˚F.

In addition, in theoretical meteorology, an absolute temperature scale is used (scaleKelvin ), K. The zero of this scale corresponds to the complete cessation of the thermal motion of molecules, that is, the lowest possible temperature. On the Celsius scale, this will be -273 ˚С

To identify the general patterns of temperature changes, an indicator of average temperatures is used: average daily, average monthly, average annual.

Determine the average annual temperature in Ust-Kamenogorsk

Examination:

Negative: -10°+(-7°)+(-2°)+(-2°)+(-6°)= -27°С

Positive: 6°+13°+17°+18°+16°+12°+5°=+87°С

Average dailyt: 87° - 27°= 60°: 12=+5°С

Determining the change in temperature, usually note its highest and lowest rates. The difference between the highest and lowest scores is calledamplitude temperatures. Write down the definition.

Determine the temperature amplitude according to the table and diagrams on the slide .

Exercise : according to fig. 86, p.94 determine the amplitude of the air temperature, using the readings of the third pair of thermometers.

Educational practical work.

Drawing up a graph of the daily course of temperature (under the guidance of a teacher)

Isotherms - these are lines connecting points with the same average air temperature for a certain period of time.

Usually show isotherms of the warmest and coldest months of the year, i.e. July and January.

IV . Consolidation of what has been learned.

Textbook page 94

V . Homework.

§24, questions

On Sunday, mark the air temperature at 9:00, 12:00, 15:00, 18:00, 21:00. Enter data into a table

9 h

12 h

15 h

18 h

21 h

The daily and annual course of air temperature in the surface layer of the atmosphere is determined by the temperature at a height of 2 m. Basically, this course is due to the corresponding course of the temperature of the active surface. Features of the course of air temperature are determined by its extremes, that is, the highest and lowest temperatures. The difference between these temperatures is called the amplitude of the course of air temperature. The pattern of daily and annual variations in air temperature is revealed by averaging the results of long-term observations. It is associated with periodic fluctuations. Non-periodic disturbances of the daily and annual course, caused by the intrusion of warm or cold air masses, distort the normal course of air temperature. The heat absorbed by the active surface is transferred to the adjacent air layer. In this case, there is some delay in the increase and decrease in air temperature compared to changes in soil temperature. In the normal course of temperature, the minimum temperature is observed before sunrise, the maximum is observed at 14-15 hours (Fig. 4.4).

Figure 4.4. The daily course of air temperature in Barnaul(available when downloading the full version of the tutorial)

Amplitude of diurnal variation of air temperature over land is always less than the amplitude of the daily variation of the soil surface temperature and depends on the same factors, that is, on the season, latitude, cloudiness, terrain, as well as on the nature of the active surface and height above sea level. Amplitude of the annual course calculated as the difference between the mean monthly temperatures of the warmest and coldest months. Absolute annual temperature amplitude called the difference between the absolute maximum and the absolute minimum air temperature for the year, that is, between the highest and lowest temperatures observed during the year. The amplitude of the annual course of air temperature in a given place depends on the geographical latitude, distance from the sea, altitude of the place, on the annual course of cloudiness and a number of other factors. Small annual temperature amplitudes are observed over the sea and are characteristic of the maritime climate. Over land, there are large annual temperature amplitudes characteristic of the continental climate. However, the maritime climate also extends to the regions of the continents adjacent to the sea, where the frequency of sea air masses is high. Sea air brings a maritime climate to land. With the distance from the ocean deep into the mainland, the annual temperature amplitudes increase, that is, the continentality of the climate increases.

By the value of the amplitude and by the time of onset of extreme temperatures, they distinguish four types of annual variation in air temperature. equatorial type It is characterized by two maxima - after the spring and autumn equinoxes, when the Sun is at its zenith at noon, and two minima - after the summer and earth solstices. This type is characterized by a small amplitude: over the continents within 5-10°C, and over the oceans only about 1°C. tropical type characterized by one maximum - after the summer solstice and one minimum - after the winter solstice. The amplitude increases with distance from the equator and averages 10-20°С over the continents and 5-10°С over the oceans. Temperate type characterized by the fact that extremes are observed over the continents at the same time as in the case of the tropical type, and over the ocean a month later. The amplitude increases with latitude, reaching 50-60°C over the continents and 15-20°C over the oceans. polar type similar to the previous type, but differs in a further increase in amplitude, reaching 25-40°С over the ocean and coasts, and exceeding 65°С over land

January and July isotherms on the territory of Russia??????

Lucas Rein Student (237) 1 year ago

THERMAL BELT OF THE EARTH, temperature zones of the Earth, - a system for classifying climates by air temperature. Usually distinguished: hot zone - between annual isotherms 20 ° (reaches 30 ° latitude); 2 temperate zones (in each hemisphere) - between the annual isotherm of 20 ° and the isotherm of the warmest month. 10°; 2 cold belts - between the isotherms of the warmest month. 10° and 0°; 2 belts of eternal frost - from cf. temperature of the warmest month. below 0°.

Juliette Student (237) 1 year ago

Thermal belts are wide bands encircling the Earth, with close air temperatures inside the belt and differing from neighboring ones by a non-uniform latitudinal distribution of solar radiation. There are seven thermal zones: hot on both sides of the equator, limited by annual isotherms of +20°С; temperate 2 (northern and southern) with a boundary isotherm of +10°С of the warmest month; cold 2 within +10°С and 0°С of the warmest month of eternal frost 2 with an average annual air temperature below 0°С.

Optical phenomena. As already mentioned, when the rays of the Sun pass through the atmosphere, part of the direct solar radiation is absorbed by air molecules, scattered and reflected. As a result of this, various optical phenomena are observed in the atmosphere, which are perceived directly by our eye. These phenomena include: sky color, refraction, mirages, halo, rainbow, false sun, light pillars, light crosses, etc.

Sky color. Everyone knows that the color of the sky changes depending on the state of the atmosphere. A clear cloudless sky during the day has a blue color. This color of the sky is due to the fact that there is a lot of scattered solar radiation in the atmosphere, which is dominated by short waves that we perceive as blue or blue. If the air is dusty, then the spectral composition of the scattered radiation changes, the blue of the sky weakens; the sky turns white. The more cloudy the air, the weaker the blue of the sky.

The color of the sky changes with height. At a height of 15 to 20 km the color of the sky is black and purple. From the tops of high mountains, the color of the sky seems deep blue, and from the surface of the Earth - blue. This change in color from black-violet to light blue is due to the ever-increasing scattering of first violet, then blue and blue rays.

At sunrise and sunset, when the sun's rays pass through the greatest thickness of the atmosphere and at the same time lose almost all short-wave rays (violet and blue), and only long-wave rays reach the observer's eye, the color of the part of the sky near the horizon and the Sun itself has a red or orange color .

Refraction. As a result of the reflection and refraction of the sun's rays as they pass through layers of air of different density, their trajectory undergoes some changes. This leads to the fact that we see celestial bodies and distant objects on the earth's surface in a direction slightly different from the one in which they are actually located. For example, if we look at the top of a mountain from a valley, then the mountain seems to us to be elevated; when sighting from the mountain into the valley, an increase in the bottom of the valley is noticed.

The angle formed by a straight line from the observer's eye to a point and the direction in which the eye sees that point is called refraction.

The amount of refraction observed at the earth's surface depends on the distribution of the density of the lower layers of air and on the distance from the observer to the object. The density of air depends on temperature and pressure. On average, the magnitude of the earth's refraction, depending on the distance to the observed objects under normal atmospheric conditions, is:

Mirages. Mirage phenomena are associated with anomalous refraction of the sun's rays, which is caused by a sharp change in air density in the lower atmosphere. With a mirage, the observer sees, in addition to objects, their images are also lower or higher than the actual position of the objects, and sometimes to the right or left of them. Often the observer can only see the image without seeing the objects themselves.

If the air density drops sharply with height, then the image of objects is observed above their actual location. So, for example, under such conditions, you can see the silhouette of the ship above sea level, when the ship is hidden from the observer beyond the horizon.

Inferior mirages are often observed on open plains, especially in deserts, where air density increases sharply with height. In this case, a person often sees in the distance, as it were, a watery, slightly undulating surface. If at the same time there are any objects on the horizon, then they seem to rise above this water. And in this water space one can see their outlines turned upside down, as if reflected in the water. The visibility of the water surface on the plain is created as a result of a large refraction, which causes the reverse image below the earth's surface of the part of the sky behind the objects.

Halo. The phenomenon of a halo refers to light or iridescent circles, sometimes observed around the Sun or Moon. A halo happens when these celestial bodies have to be seen through light cirrus clouds or through a veil of fog, consisting of ice needles suspended in the air (Fig. 63).

The phenomenon of the halo occurs due to refraction in ice crystals and reflection from their faces of the sun's rays.

Rainbow. A rainbow is a large multi-colored arc, usually observed after rain against the background of rain clouds located against that part of the sky where the Sun shines. The magnitude of the arc is different, sometimes there is a full iridescent semicircle. We often see two rainbows at the same time. The intensity of development of individual colors in the rainbow and the width of their bands are different. In a well-visible rainbow, red is located on one side and purple on the other; the rest of the colors in the rainbow are in the order of the colors of the spectrum.

Rainbows are caused by the refraction and reflection of sunlight in water droplets in the atmosphere.

Sound phenomena in the atmosphere. Longitudinal vibrations of particles of matter, propagating through the material medium (through air, water and solids) and reaching the human ear, cause sensations called "sound".

Atmospheric air always contains sound waves of various frequencies and strengths. Some of these waves are created artificially by man, and some of the sounds are of meteorological origin.

The sounds of meteorological origin include thunder, the howling of the wind, the hum of wires, the noise and rustle of trees, the "voice of the sea", the sounds and noises that occur during the movement of sand masses in deserts and over dunes, as well as snowflakes over a smooth surface of snow, sounds when falling on the earth's surface of solid and liquid precipitation, the sounds of the surf near the shores of the seas and lakes, etc. Let us dwell on some of them.

Thunder is observed during the phenomena of a lightning discharge. It arises in connection with the special thermodynamic conditions that are created on the path of lightning movement. Usually we perceive thunder in the form of a series of blows - the so-called peals. Thunderclaps are explained by the fact that sounds generated at the same time along the long and usually winding path of lightning reach the observer sequentially and with different intensities. Thunder, despite the great power of sound, is heard at a distance of no more than 20-25 km(average about 15 km).

The howl of the wind occurs when the air moves rapidly with a swirl of some objects. In this case, there is an alternation of accumulation and outflow of air from objects, which gives rise to sounds. The buzz of wires, the noise and rustle of trees, the "voice of the sea" are also connected by air movement.

The speed of sound in the atmosphere. The speed of sound propagation in the atmosphere is affected by the temperature and humidity of the air, as well as the wind (direction and its strength). The average speed of sound in the atmosphere is 333 m per second. As the air temperature increases, the speed of sound increases slightly. A change in the absolute humidity of the air has a smaller effect on the speed of sound. The wind has a strong influence: the speed of sound in the direction of the wind increases, against the wind it decreases.

Knowledge of the speed of sound propagation in the atmosphere is of great importance in solving a number of problems in studying the upper layers of the atmosphere by the acoustic method. Using the average speed of sound in the atmosphere, you can find out the distance from your location to the location of the thunder. To do this, you need to determine the number of seconds between the visible flash of lightning and the moment the sound of thunder arrives. Then you need to multiply the average value of the speed of sound in the atmosphere - 333 m/sec. for the given number of seconds.

Echo. Sound waves, like light rays, experience refraction and reflection when passing from one medium to another. Sound waves can be reflected from the earth's surface, from water, from surrounding mountains, clouds, from the interface between air layers having different temperatures and humidity. The sound, reflected, can be repeated. The phenomenon of repetition of sounds due to the reflection of sound waves from different surfaces is called "echo".

Especially often the echo is observed in the mountains, near the rocks, where a loudly spoken word is repeated one or several times after a certain period of time. So, for example, in the Rhine Valley there is a Lorelei rock, in which the echo is repeated up to 17-20 times. An example of an echo is the peals of thunder, which arise as a result of the reflection of the sounds of electrical discharges from various objects on the earth's surface.

Electrical phenomena in the atmosphere. Electrical phenomena observed in the atmosphere are associated with the presence in the air of electrically charged atoms and gas molecules called ions. Ions come in both negative and positive charges, and according to the size of the masses are divided into light and heavy. The ionization of the atmosphere occurs under the influence of the short-wave part of solar radiation, cosmic rays and radiation of radioactive substances contained in the earth's crust and in the atmosphere itself. The essence of ionization lies in the fact that these ionizers transfer energy to a neutral molecule or atom of air gas, under the action of which one of the outer electrons is removed from the sphere of action of the nucleus. As a result, an atom deprived of one electron becomes a positive light ion. An electron removed from a given atom quickly joins a neutral atom and in this way a negative light ion is created. Light ions, meeting with suspended particles of air, give them their charge and thus form heavy ions.

The number of ions in the atmosphere increases with height. On average for every 2 km height, their number increases by a thousand ions in one cubic meter. centimeter. In the high layers of the atmosphere, the maximum concentration of ions is observed at altitudes of about 100 and 250 km.

The presence of ions in the atmosphere creates the electrical conductivity of the air and the electric field in the atmosphere.

The conductivity of the atmosphere is created due to the high mobility of mainly light ions. Heavy ions play a small role in this respect. The higher the concentration of light ions in the air, the greater its conductivity. And since the number of light ions increases with height, the conductivity of the atmosphere also increases with height. So, for example, at a height of 7-8 km conductivity is approximately 15-20 times greater than that of the earth's surface. At about 100 km conductivity is very high.

Clean air has few suspended particles, so it contains more light ions and fewer heavy ones. In this regard, the conductivity of clean air is higher than the conductivity of dusty air. Therefore, in haze and fog, conductivity has a low value. The electric field in the atmosphere was first established by M. V. Lomonosov. In clear cloudless weather, the field strength is considered normal. Towards

Earth's surface atmosphere is positively charged. Under the influence of the electric field of the atmosphere and the negative field of the earth's surface, a vertical current of positive ions is established from the earth's surface upwards, and negative ions from the atmosphere downwards. The electric field of the atmosphere near the earth's surface is extremely variable and depends on the conductivity of the air. The lower the conductivity of the atmosphere, the greater the electric field strength of the atmosphere. The conductivity of the atmosphere mainly depends on the amount of solid and liquid particles suspended in it. Therefore, during haze, during precipitation and fog, the intensity of the electric field of the atmosphere increases and this often leads to electric discharges.

Elm's Lights. During thunderstorms and squalls in summer or snowstorms in winter, one can sometimes observe quiet electrical discharges on the tips of objects protruding above the earth's surface. These visible discharges are called "Elmo's fires" (Fig. 64). Most often, Elmo's lights are observed on masts, on mountain tops; sometimes they are accompanied by a slight crackle.

Elmo fires are formed at a high electric field strength. The tension is so great that ions and electrons, moving at high speed, split air molecules on their way, which increases the number of ions and electrons in the air. In this regard, the conductivity of air increases and from sharp objects where electricity accumulates, the outflow of electricity and discharge begins.

Lightning. As a result of complex thermal and dynamic processes in thunderclouds, electric charges are separated: usually negative charges are located at the bottom of the cloud, positive charges at the top. In connection with such a separation of space charges inside the clouds, strong electric fields are created both inside the clouds and between them. In this case, the field strength near the earth's surface can reach several hundred kilovolts per 1 m. A large electric field strength leads to the fact that electric discharges occur in the atmosphere. Strong sparking electrical discharges that occur between thunderclouds or between clouds and the earth's surface are called lightning.

The duration of a lightning flash is on average about 0.2 sec. The amount of electricity that lightning carries is 10-50 coulombs. The current strength is very large; sometimes it reaches 100-150 thousand amperes, but in most cases it does not exceed 20 thousand amperes. Most lightning is negatively charged.

According to the appearance of the spark flash, lightning is divided into linear, flat, ball, and beaded.

The most frequently observed linear lightning, among which there are a number of varieties: zigzag, branched, ribbon, rocket, etc. If linear lightning is formed between the cloud and the earth's surface, then its average length is 2-3 km; lightning between clouds can reach 15-20 km length. The discharge channel of lightning, which is created under the influence of air ionization and through which there is an intense counter-flow of negative charges accumulated in clouds and positive charges accumulated on the earth's surface, has a diameter of 3 to 60 cm.

Flat lightning is a short-term electrical discharge covering a significant part of the cloud. Flat lightning is not always accompanied by thunder.

Ball lightning is a rare occurrence. It is formed in some cases after a strong discharge of linear lightning. Ball lightning is a fireball with a diameter of usually 10-20 cm(and sometimes up to several meters). On the earth's surface, this lightning moves at a moderate speed and has a tendency to penetrate inside buildings through chimneys and other small openings. Without causing harm and having done complex movements, ball lightning can safely leave the building. Sometimes it causes fires and destruction.

An even rarer occurrence is beaded lightning. They occur when an electric discharge consists of a series of luminous spherical or oblong bodies.

Lightning often causes great damage; they destroy buildings, start fires, melt electrical wires, split trees, and injure people. To protect buildings, industrial structures, bridges, power plants, power lines and other structures from direct lightning strikes, lightning rods are used (usually they are called lightning rods).

The greatest number of days with thunderstorms is observed in tropical and equatorial countries. So, for example, on about. Java has 220 days with thunderstorms in a year, 150 days in Central Africa, and about 140 in Central America. In the USSR, the most days with thunderstorms occur in the Caucasus (up to 40 days a year), in Ukraine and in the southeast of the European part of the USSR. Thunderstorms are usually observed in the afternoon, especially between 15 and 18 hours.

Polar Lights. Auroras are a peculiar form of glow in the high layers of the atmosphere, observed at times at night, mainly in the polar and circumpolar countries of the northern and southern hemispheres (Fig. 65). These glows are a manifestation of the electrical forces of the atmosphere and occur at an altitude of 80 up to 1000 km in highly rarefied air when electric charges pass through it. The nature of the auroras has not yet been fully unraveled, but it has been precisely established that the cause of their occurrence is

the impact of the upper highly rarefied layers of the earth's atmosphere of charged particles (corpuscles) entering the atmosphere from active regions of the sun (spots, prominences and other areas) during solar flares.

The maximum number of auroras is observed near the Earth's magnetic poles. So, for example, at the magnetic pole of the northern hemisphere, there are up to 100 auroras per year.

According to the shape of the glow, the auroras are very diverse, but they are usually divided into two main groups: auroras of a non-radiant form (uniform stripes, arcs, calm and pulsating luminous surfaces, diffuse glows, etc.) and auroras of a radiant structure (stripes, drapes, rays, corona and etc.). Auroras of a beamless structure are characterized by a calm glow. The radiances of the ray structure, on the contrary, are mobile, they change both the shape and the brightness and color of the glow. In addition, auroras of radiant form are accompanied by magnetic excitations.

The following types of precipitation are distinguished according to the form. Rain- liquid precipitation, consisting of drops with a diameter of 0.5-6 mm. Larger droplets break into pieces as they fall. In torrential rains, the size of the drops is larger than in continuous ones, especially at the beginning of the rain. At negative temperatures, supercooled drops can sometimes fall out. In contact with the earth's surface, they freeze and cover it with an ice crust. Drizzle - liquid precipitation, consisting of drops with a diameter of about 0.5-0.05 mm with a very low falling speed. They are easily carried by the wind in a horizontal direction. Snow- solid precipitation, consisting of complex ice crystals (snowflakes). Their forms are very diverse and depend on the conditions of education. The main form of snow crystals is a six-pointed star. Stars are obtained from hexagonal plates, because the sublimation of water vapor occurs most rapidly at the corners of the plates, where the rays grow. On these rays, in turn, branches are created. The diameters of the falling snowflakes can be very different grits, snow and ice, - precipitation consisting of icy and heavily grained snowflakes with a diameter of more than 1 mm. Most often, croup is observed at temperatures close to zero, especially in autumn and spring. Snow groats have a snow-like structure: grains are easily compressed by fingers. Nuclei of ice grains have a icy surface. It is difficult to crush them; when they fall to the ground, they jump. From stratus clouds in winter instead of drizzle fall snow grains- small grains with a diameter of less than 1 mm, resembling semolina. In winter, at low temperatures, sometimes fall out of the clouds of the lower or middle tier snow needles- sediments consisting of ice crystals in the form of hexagonal prisms and plates without branching. With significant frosts, such crystals can occur in the air near the earth's surface. They are especially well seen on a sunny day, when their facets sparkle, reflecting the sun's rays. Clouds of the upper tier are composed of such ice needles. Has a special character freezing rain- precipitation consisting of transparent ice balls (raindrops frozen in the air) with a diameter of 1-3 mm. Their loss clearly indicates the presence of a temperature inversion. Somewhere in the atmosphere there is a layer of air with a positive temperature

In recent years, several methods have been proposed and successfully tested for the artificial precipitation of clouds and the formation of precipitation from them. To do this, small particles (“grains”) of solid carbon dioxide having a temperature of about -70 ° C are scattered from an aircraft in a supercooled drop cloud. Due to such a low temperature, a huge number of very small ice crystals form around these grains in the air. These crystals are then dispersed in the cloud due to the movement of air. They serve as the germs on which large snowflakes later grow - exactly as described above (§ 310). In this case, a wide (1-2 km) gap is formed in the cloud layer along the entire path that the aircraft has traveled (Fig. 510). The resulting snowflakes can create quite a heavy snowfall. It goes without saying that only as much water can be precipitated in this way as was previously contained in the cloud. To strengthen the process of condensation and the formation of primary, smallest cloud drops is not yet within the power of man.

Clouds- products of water vapor condensation suspended in the atmosphere, visible in the sky from the surface of the earth.

Clouds are made up of tiny drops of water and/or ice crystals (called cloud elements). Droplet cloud elements are observed when the air temperature in the cloud is above −10 °C; from -10 to -15 °C, clouds have a mixed composition (drops and crystals), and at temperatures in the cloud below -15 °C, they are crystalline.

Clouds are classified into a system that uses Latin words for the appearance of clouds as seen from the ground. The table summarizes the four main components of this classification system (Ahrens, 1994).

Further classification describes the clouds according to their height. For example, clouds containing the prefix "cirr-" in their name as cirrus clouds are located in the upper tier, while clouds with the prefix " alto-" in the name, such as high-stratus (altostratus), are in the middle tier. Several groups of clouds are distinguished here. The first three groups are determined by their height above the ground. The fourth group consists of clouds of vertical development. The last group includes a collection of mixed types clouds.

Lower clouds Lower clouds are mostly composed of water droplets because they are located at altitudes below 2 km. However, when temperatures are low enough, these clouds can also contain ice particles and snow.

Clouds of vertical development These are cumulus clouds that look like isolated cloud masses, the vertical dimensions of which are of the same order as the horizontal ones. They are usually called temperature convection or front lift, and can grow to heights of 12 km, realizing the growing energy through condensation water vapor within the cloud itself.

Other types of clouds Finally, we present collections of mixed cloud types that do not fit into any of the four previous groups.

Most of Russia is characterized by moderate rainfall. In the Aral-Caspian and Turkestan steppes, as well as in the far North, they even fall very little. Very rainy areas include only some of the southern outskirts of Russia, especially Transcaucasia.

Pressure

Atmosphere pressure- the pressure of the atmosphere on all objects in it and the earth's surface. Atmospheric pressure is created by the gravitational attraction of air to the Earth. Atmospheric pressure is measured with a barometer. Atmospheric pressure equal to the pressure of a column of mercury 760 mm high at 0 °C is called normal atmospheric pressure. (International standard atmosphere - ISA, 101 325 Pa

The presence of atmospheric pressure confused people in 1638, when the idea of ​​the Duke of Tuscany to decorate the gardens of Florence with fountains failed - the water did not rise above 10.3 meters. The search for the reasons for this and experiments with a heavier substance - mercury, undertaken by Evangelista Torricelli, led to the fact that in 1643 he proved that air has weight. Together with V. Viviani, Torricelli conducted the first experiment on measuring atmospheric pressure, inventing pipe Torricelli(the first mercury barometer) - a glass tube in which there is no air. In such a tube, mercury rises to a height of about 760 mm. Measurementpressure necessary for process control and production safety. In addition, this parameter is used for indirect measurements of other process parameters: level, flow, temperature, density etc. In the SI system, the unit of pressure is taken pascal (Pa) .

In most cases, primary pressure transducers have a non-electrical output signal in the form of force or displacement and are combined in one unit with a measuring device. If the measurement results must be transmitted over a distance, then an intermediate conversion of this non-electrical signal into a unified electrical or pneumatic signal is used. In this case, the primary and intermediate converters are combined into one measuring converter.

Used to measure pressure pressure gauges, vacuum gauges, combined pressure and vacuum meters, pressure gauges, thrust gauges, thrust gauges, Pressure Sensors, differential pressure gauges.

In most devices, the measured pressure is converted into a deformation of elastic elements, so they are called deformation.

Deformation devices are widely used to measure pressure in the conduct of technological processes due to the simplicity of the device, convenience and safety in operation. All deformation devices have some kind of elastic element in the circuit, which is deformed under the action of the measured pressure: tubular spring, membrane or bellows.

Distribution

On the earth's surface Atmosphere pressure varies from place to place and over time. Non-periodic changes are especially important Atmosphere pressure associated with the emergence, development and destruction of slowly moving high pressure areas - anticyclones and relatively fast moving huge whirlwinds - cyclones, where low pressure prevails. Extreme values ​​noted so far Atmosphere pressure(at sea level): 808.7 and 684.0 mmHg cm. However, despite the large variability, the distribution of monthly averages Atmosphere pressure on the surface of the globe every year is about the same. Average annual Atmosphere pressure lowered near the equator and has a minimum of 10 ° N. sh. Further Atmosphere pressure rises and reaches a maximum at 30-35 ° north and south latitude; then Atmosphere pressure decreases again, reaching a minimum at 60-65°, and rises again towards the poles. For this latitudinal distribution Atmosphere pressure the time of year and the nature of the distribution of continents and oceans have a significant influence. Over cold continents in winter there are areas of high Atmosphere pressure So the latitudinal distribution Atmosphere pressure is disturbed, and the pressure field breaks up into a series of high and low pressure areas, which are called centers of action of the atmosphere. With height, the horizontal distribution of pressure becomes simpler, approaching the latitudinal one. Starting from a height of about 5 km Atmosphere pressure throughout the globe decreases from the equator to the poles. In the daily course Atmosphere pressure 2 maxima are detected: at 9-10 h and 21-22 h, and 2 lows: in 3-4 h and 15-16 h. It has a particularly regular daily course in tropical countries, where the daily fluctuation reaches 2.4 mmHg Art., and night - 1.6 mmHg cm. With increasing latitude, the amplitude of change Atmosphere pressure decreases, but at the same time non-periodic changes become stronger Atmosphere pressure

The air is constantly moving: it rises - an upward movement, it falls - a downward movement. The movement of air in a horizontal direction is called wind. The reason for the occurrence of wind is the uneven distribution of air pressure on the surface of the Earth, which is caused by an uneven distribution of temperature. In this case, the air flow moves from places with high pressure to the side where the pressure is less. With the wind, the air does not move evenly, but in shocks, gusts, especially near the surface of the Earth. There are many reasons that affect the movement of air: the friction of the air flow on the surface of the Earth, encountering obstacles, etc. In addition, air flows under the influence of the rotation of the Earth deviate to the right in the northern hemisphere, and to the left in the southern hemisphere. Wind is characterized by speed, direction and strength. Wind speed is measured in meters per second (m/s), kilometers per hour (km/h), points (on the Beaufort scale from 0 to 12, currently up to 13 points). The wind speed depends on the pressure difference and is directly proportional to it: the greater the pressure difference (horizontal baric gradient), the greater the wind speed. The average long-term wind speed at the earth's surface is 4-9 m/s, rarely more than 15 m/s. In storms and hurricanes (temperate latitudes) - up to 30 m/s, in gusts up to 60 m/s. In tropical hurricanes, wind speeds reach up to 65 m/s, and in gusts they can reach 120 m/s. The direction of the wind is determined by the side of the horizon from which the wind is blowing. To designate it, eight main directions (rhumbs) are used: N, NW, W, SW, S, SE, B, NE. The direction depends on the pressure distribution and on the deflecting effect of the Earth's rotation. The strength of the wind depends on its speed and shows what dynamic pressure the air flow exerts on any surface. Wind strength is measured in kilograms per square meter (kg/m2). Winds are extremely diverse in origin, nature and significance. So, in temperate latitudes, where western transport dominates, westerly winds (NW, W, SW) prevail. These areas occupy vast spaces - from about 30 to 60 in each hemisphere. In the polar regions, winds blow from the poles to low pressure zones of temperate latitudes. These areas are dominated by northeasterly winds in the Arctic and southeasterly winds in the Antarctic. At the same time, the southeast winds of the Antarctic, in contrast to the Arctic ones, are more stable and have high speeds. The most extensive wind zone of the globe is located in tropical latitudes, where the trade winds blow. The trade winds are the constant winds of tropical latitudes. They are common in the zone from 30s. sh. up to 30. sh. , that is, the width of each zone is 2-2.5 thousand km. These are steady winds of moderate speed (5-8 m/s). At the earth's surface, due to friction and the deflecting action of the Earth's daily rotation, they have a predominant northeasterly direction in the northern hemisphere and a southeasterly direction in the southern hemisphere (Fig. IV.2). They are formed because in the equatorial zone, heated air rises, and tropical air comes in its place from the north and south. The trade winds were and are of great practical importance in navigation, especially earlier for the sailing fleet, when they were called "trade winds". These winds form stable surface currents in the ocean along the equator, directed from east to west. It was they who brought the caravels of Columbus to America. Breezes are local winds that blow from sea to land during the day and from land to sea at night. In this regard, day and night breezes are distinguished. The daytime (sea) breeze is formed as a result of the fact that during the day the land heats up faster than the sea, and a lower pressure is established above it. At this time, over the sea (more chilled), the pressure is higher and the air begins to move from the sea to the land. The night (coastal) breeze blows from land to sea, since at this time the land cools faster than the sea, and reduced pressure is above the water surface - air moves from the coast to the sea.

Wind speed at weather stations is measured with anemometers; if the device is self-recording, then it is called an anemograph. Anemorumbograph determines not only the speed, but also the direction of the wind in the mode of constant registration. Instruments for measuring wind speed are installed at a height of 10-15 m above the surface, and the wind measured by them is called the wind near the earth's surface.

The direction of the wind is determined by naming the point on the horizon from where the wind blows or the angle formed by the direction of the wind with the meridian of the place where the wind blows, i.e. its azimuth. In the first case, 8 main points of the horizon are distinguished: north, northeast, east, southeast, south, southwest, west, northwest and 8 intermediate ones. 8 main directions of the direction have the following abbreviations (Russian and international): С-N, Yu-S, З-W, В-E, СЗ-NW, СВ-NE, SW-SW, SE- SE.

Air masses and fronts

Air masses are called relatively homogeneous air masses in terms of temperature and humidity, which spread over an area of ​​​​several thousand kilometers and several kilometers in height.

They are formed under conditions of a long stay on more or less homogeneous surfaces of land or ocean. Moving in the process of general circulation of the atmosphere to other areas of the Earth, air masses are transported to these areas and their own weather regime. The dominance of certain air masses in a given region in a given season creates characteristic climatic regime of the area.

There are four main geographical types of air masses that cover the entire troposphere of the Earth. These are the masses of Arctic (Antarctic), temperate, tropical and equatorial air. With the exception of the rest, in each of them, marine and continental varieties are also distinguished, which are formed in accordance with land and ocean .

Polar (Arctic and Antarctic) air forms over the ice surfaces of the polar regions and is characterized by low temperatures, low moisture content and good transparency.

Moderate air is much better warmed up, it is marked in summer by an increased moisture content, especially over the ocean. The prevailing western winds and cyclones of the sea temperate air are transported and Aleko to the depths of the continents, often accompanying their way with precipitation

Tropical air is generally characterized by high temperatures. But if over the sea it is also very humid, then over land, on the contrary, it is extremely dry and dusty.

Equatorial air is marked by constant high temperatures and increased moisture content both over the ocean and over land. In the afternoon, there are frequent heavy rains.

Air masses with different temperatures and humidity are constantly moving and meet each other in a narrow space. The conditional surface separating the air masses is called the atmospheric front. When this imaginary surface intersects with the earth's surface, the so-called atmospheric front line is formed.

The surface separating arctic (antarctic) and temperate air is called the arctic and antarctic fronts, respectively. Air from temperate latitudes and tropics separates the polar front. Since the density of warm air is less than the density of cold air, the front is an inclined plane, which always has an inclination towards cold air. at a very small angle (less than 1 °) to the surface of the earth. Cold air, as thicker, when meeting with warm air, seems to swim under it and lift it up, causing the formation of XMAmar.

Having met, various air masses continue to move towards the mass, which moved at a higher speed. At the same time, the position of the frontal surface, which separates these air masses, changes depending on the direction of movement of the frontal surface. Cold and warm fronts are distinguished. cold After the passage of a cold front, atmospheric pressure rises, and air humidity decreases. When warm air advances and the front moves towards lower temperatures, the front is called warm. When a warm front passes, warming occurs, the pressure decreases, and the temperature rises.

Fronts are of great importance for the weather, since clouds form near them and precipitation often falls. In places where warm and cold air meet, cyclones arise and develop, the weather becomes bad. Knowing the location of atmospheric fronts, the direction and speed of their movement, as well as having meteorological data, characterizing air masses, make weather forecasts.

Anticyclone- an area of ​​high atmospheric pressure with closed concentric isobars at sea level and with a corresponding wind distribution. In a low anticyclone - cold, the isobars remain closed only in the lowest layers of the troposphere (up to 1.5 km), and in the middle troposphere, increased pressure is not detected at all; the presence of a high-altitude cyclone above such an anticyclone is also possible.

A high anticyclone is warm and retains closed isobars with anticyclonic circulation even in the upper troposphere. Sometimes the anticyclone is multicenter. The air in the anticyclone in the northern hemisphere moves around the center clockwise (that is, deviates from the baric gradient to the right), in the southern hemisphere - counterclockwise. The anticyclone is characterized by the predominance of clear or slightly cloudy weather. Due to the cooling of air from the earth's surface in the cold season and at night in the anticyclone, the formation of surface inversions and low stratus clouds (St) and fogs is possible. In summer, moderate daytime convection with the formation of cumulus clouds is possible over land. Convection with the formation of cumulus clouds is also observed in the trade winds on the periphery of subtropical anticyclones facing the equator. When an anticyclone stabilizes at low latitudes, powerful, high and warm subtropical anticyclones arise. The stabilization of anticyclones also occurs in the middle and polar latitudes. High, slow-moving anticyclones that disrupt the general westerly transfer of mid-latitudes are called blocking anticyclones.

Synonyms: high pressure area, high pressure area, baric maximum.

Anticyclones reach a size of several thousand kilometers in diameter. In the center of the anticyclone, the pressure is usually 1020-1030 mbar, but can reach 1070-1080 mbar. Like cyclones, anticyclones move in the direction of the general transport of air in the troposphere, that is, from west to east, while deviating to low latitudes. The average speed of the anticyclone movement is about 30 km/h in the Northern Hemisphere and about 40 km/h in the Southern Hemisphere, but often the anticyclone becomes inactive for a long time.

Signs of an anticyclone:

Clear or partly cloudy weather

No wind

No precipitation

Stable weather pattern (does not change noticeably over time as long as an anticyclone exists)

In summer, the anticyclone brings hot, cloudy weather. In winter, the anticyclone brings severe frosts, sometimes frosty fog is also possible.

An important feature of anticyclones is their formation in certain areas. In particular, anticyclones form over ice fields. And the more powerful the ice cover, the more pronounced the anticyclone; that is why the anticyclone over Antarctica is very powerful, and over Greenland it is low-power, over the Arctic it is medium in severity. Powerful anticyclones also develop in the tropical zone.

Cyclone(from other Greek κυκλῶν - “rotating”) - an atmospheric vortex of huge (from hundreds to several thousand kilometers) diameter with reduced air pressure in the center.

Air movement (dashed arrows) and isobars (solid lines) in a cyclone in the northern hemisphere.

Vertical section of a tropical cyclone

Air in cyclones circulates counterclockwise in the northern hemisphere and clockwise in the southern. In addition, in the air layers at a height from the earth's surface to several hundred meters, the wind has a term directed towards the center of the cyclone along the baric gradient (in the direction of decreasing pressure). The value of the term decreases with height.

Schematic representation of the process of formation of cyclones (black arrows) due to the rotation of the Earth (blue arrows).

A cyclone is not just the opposite of an anticyclone, they have a different mechanism of occurrence. Cyclones constantly and naturally appear due to the rotation of the Earth, thanks to the Coriolis force. A consequence of Brouwer's fixed point theorem is the presence of at least one cyclone or anticyclone in the atmosphere.

There are two main types of cyclones - extratropical and tropical. The first are formed in temperate or polar latitudes and have a diameter of thousands of kilometers at the beginning of development, and up to several thousand in the case of the so-called central cyclone. Among the extratropical cyclones, southern cyclones are distinguished, which form at the southern border of temperate latitudes (Mediterranean, Balkan, Black Sea, South Caspian, etc.) and move to the north and northeast. Southern cyclones have colossal reserves of energy; It is with the southern cyclones in central Russia and the CIS that the heaviest precipitation, winds, thunderstorms, squalls and other weather phenomena are associated.

Tropical cyclones form in tropical latitudes and are smaller (hundreds, rarely more than a thousand kilometers), but have larger baric gradients and wind speeds reaching pre-storm levels. Such cyclones are also characterized by the so-called. "eye of the storm" - a central area with a diameter of 20-30 km with relatively clear and calm weather. Tropical cyclones can transform into extratropical cyclones during their development. Below 8-10 ° north and south latitude, cyclones occur very rarely, and in the immediate vicinity of the equator they do not occur at all.

Cyclones occur not only in the Earth's atmosphere, but also in the atmospheres of other planets. For example, in the atmosphere of Jupiter, the so-called Great Red Spot has been observed for many years, which is, apparently, a long-lived anticyclone.

Number: 15.02.2016

Class: 6"B"

Lesson #42

Lesson topic:§39. Air temperature and diurnal temperature variation

The purpose of the lesson:

Tutorial: To form knowledge about the patterns of distribution of air temperature.

Developing I : To develop skills, the ability to determine the temperature, calculate the daily rate, draw up graphs, solve problems of temperature changes, find the amplitude of temperatures.

Nurturing: To develop the desire to study the subject.

Lesson type: combined

Type of lesson: problem learning

Equipmentlesson: ICT, thermometers, weather calendars,

I. Organizational moment: Greetings. Identification of absentees.

II.Checking homework:

Test.

1. What reasons determine the heating of the Earth?

A polar night and a polar day

B angle of incidence of the sun's rays

In the change of day and night

G pressure, temperature, wind.

2. What is the difference in surface heating at the equator and temperate latitudes:

And the equatorial latitudes are heated more during the year

B equatorial latitudes are heated more in summer

In equatorial latitudes, they are heated equally throughout the year

3.How many lighting zones?

A 3 B 5 C 6 D 4

4. What are the features of the polar belt

A Twice a year Sun on the tropic

B During the year there is a polar day and a polar night

In Summer the Sun is at its zenith.

5. Does the weather often change in the tropical zone

A Yes B No C 4 times a year

III. Preparation for explaining a new topic: Write on the board the topic of the lesson, explain

IV.Explanation of the new topics:

Air temperature- the degree of air heating, determined using a thermometer.

Air temperature- one of the most important characteristics of weather and climate.

Thermometer is a device for measuring air temperature. The thermometer is a capillary tube soldered to a tank filled with a liquid (mercury, alcohol). The tube is attached to a bar on which the scale of the thermometer is applied. With warming, the liquid in the tube begins to rise, with cooling - to fall. Thermometers are outdoor and indoor.

Daily change in air temperature - amplitude.

Studies have shown that the temperature changes with time, i.e. during the day, month, year. The daily change in temperature depends on the rotation of the Earth around its axis.

At night, when there is no heat from the sun, the surface of the Earth cools. And during the day, on the contrary, it heats up.

As a result, the air temperature changes.

Lowest temperature of the day -before sunrise.

The highest temperature is 2-3 hours after noon

During the day, temperature readings at weather stations are taken 4 times: at 1 a.m., 7 a.m., 1 p.m., 7 p.m., then they are summed up and divided by 4 average daily temperature

For example:

1h +5 0 C, 7h +7 0 C, 13h +15 0 C, 19h +11 0 C,

5 0 C+7 0 C+15 0 C+11 0 C=38 0 C:4=9.5 0 C

v.Assimilation of a new topic:

Test

1. Air temperature with altitude:

a) goes down

b) rises

c) does not change

2. Land, unlike water, heats up:

a) slower

b) faster

3. Air temperature is measured:

a) a barometer

b) a thermometer

c) hygrometer

a) at 7 o'clock

b) at 12 o'clock

c) at 2 pm

5. Temperature fluctuations during the day depend on:

a) clouds

b) the angle of incidence of the sun's rays

6. Amplitude is:

a) the sum of all temperatures during the day

b) the difference between the highest temperature and the lowest

7. The average temperature (+2 o; +4 o; +3 o; -1 o) is:

VI. Lesson summary:

1. determine the amplitude of temperatures, the average daily temperature,

VII.Homework:

1.§39. Air temperature and diurnal temperature variation

VII. Grading:

Evaluation teacher student

Reasons for changes in air temperature.

The temperature of the air varies daily following the temperature of the earth's surface. Since the air is heated and cooled from the earth's surface, the amplitude of the daily temperature variation in the meteorological booth is less than on the soil surface, on average by about one third.

The rise in air temperature begins with the rise in soil temperature (15 minutes later) in the morning, after sunrise. At 13-14 hours, the temperature of the soil, as we know, begins to drop. At 14-15 hours it equalizes with the air temperature; from that time on, with a further drop in soil temperature, the air temperature also begins to fall.

The diurnal variation of air temperature is quite correctly manifested only in conditions of stable clear weather.

But on some days, the daily course of air temperature can be very wrong. It depends on changes in cloudiness as well as advection.

The daily amplitude of air temperature also varies by season, by latitude, and also depending on the nature of the soil and terrain. In winter it is less than in summer. With increasing latitude, the daily amplitude of air temperature decreases, as the midday height of the sun above the horizon decreases. Under latitudes of 20-30° on land, the average daily temperature amplitude for the year is about 12°, under latitude 60° about 6°, under latitude 70° only 3°. At the highest latitudes, where the sun does not rise or set for many days in a row, there is no regular diurnal temperature variation at all.

The temperature of the soil surface also changes during the year. In tropical latitudes, its annual amplitude, i.e., the difference in long-term average temperatures of the warmest and coldest months of the year, is small and increases with latitude. In the northern hemisphere at a latitude of 10° it is about 3°, at a latitude of 30° about 10°, and at a latitude of 50° it averages about 25°.

Reasons for changes in air temperature

Air in direct contact with the earth's surface exchanges heat with it due to molecular heat conduction. But inside the atmosphere there is another, more efficient heat transfer - by turbulent heat conduction. The mixing of air during turbulence contributes to the very rapid transfer of heat from one layer of the atmosphere to another. Turbulent thermal conductivity also increases the transfer of heat from the earth's surface to the air or vice versa. If, for example, air is cooled from the earth's surface, then by means of turbulence, warmer air from the overlying layers is continuously delivered to the place of the cooled air. This maintains a temperature difference between the air and the surface and therefore supports the transfer of heat from the air to the surface. temperature changes associated with advection - the influx of new air masses into a given place from other parts of the globe, are called advective. If air with a higher temperature flows into a given place, they speak of heat advection, if from a lower one, they speak of cold advection.

The general change in temperature at a fixed geographical point, which depends both on individual changes in the state of the air and on advection, is called a local (local) change.