Distribution of sunlight and heat on earth. Distribution of heat and light on earth Distribution of sunlight and heat on earth

Topic: DISTRIBUTION OF SUN LIGHT HEAT ON THE EARTH.

Lesson Objectives:- to form an idea of ​​the Sun as the main source of energy that determines the processes in the atmosphere; about the features of the illumination of the Earth's belts.

- identify the causes of the uneven distribution of sunlight and heat on Earth.

Develop skills in working with cartographic sources

Teaching students tolerance

Equipment: globe, climate map, physical. world map, atlases, contour maps

During the classes:

I.Organization of students for the lesson.

II. Checking homework ( complete the table).

III. Learning new material.

To explain the new material, the teacher uses a globe and a table lamp, which will be the "Sun".

The lower the Sun is above the horizon, the lower the air temperature.

The Sun is at its highest position in the sky of the Northern Hemisphere in June, and at this time there is the height of summer. The lowest is in December, and at this time it is winter there, most of our country is covered with snow.

The change of seasons occurs because the Earth moves around the Sun and the Earth's axis is inclined to the plane of the Earth's orbit, as a result of which the globe is turned towards the Sun more than the Northern, then the Southern Hemisphere. The sun is at different heights above the horizon. In the warm season, it is high above the horizon and the Earth receives a lot of heat. During the cold season, the Sun is low above the horizon, and the Earth receives less heat.

The earth makes one revolution around the sun in a year, and as it moves around it, the tilt of the earth's axis remains unchanged.

(The teacher turns on the table lamp and moves the globe around it, keeping the tilt of its axis constant.)

Some incorrectly believe that the change of seasons occurs because the Sun is closer in summer and farther from Earth in winter.

The distance from the earth to the sun per change of seasons is notaffects.

At that moment, when the Earth “turned” towards the Sun with its Northern lolus, and “turned away” from it with its Southern lolus, it is summer in the Northern Hemisphere. The sun is high above the horizon at the North Pole and around it, it does not set below the horizon around the clock. It's a polar day. South of the parallel 66.5 ° N. sh. (polar circle) the merging of day and night occurs every day. The opposite picture is observed in the Southern Hemisphere. When the globe moves, fix the students' attention on four positions of the earth:December 22, March 21, June 22 and September 21. At the same time, show the boundaries of light and shadow, the angle of the sun's rays on the parallels marked with flags. Analysis of figures in the text of the paragraph.

Belts of illumination.

The tropics and polar circles divide the earth's surface into zones of illumination.

1. Polar belts: northern and southern.

2. Tropical belt.

3. Temperate zone: northern and southern.

polar circles.

Parallels 66.50 p. w and 66.50 s. sh call polar circles. They are the boundaries of areas where there are polar days and polar nights. At a latitude of 66.50, people on the days of the summer solstice see the Sun above the horizon for a full day, that is, all 24 hours. Six months later, all 24 hours is a polar night.

From the polar circles towards the poles, the duration of the polar days and nights increases. So, at a latitude of 66.50 it is equal to 1 day, at a latitude of a day, at a latitude of 80 ° - 134 days, at a latitude of 90 ° (at the poles) - approximately six months.

Throughout the space between the polar circles, there is a change of day and night (show the North and South polar circles on a globe and a map of the hemispheres and the space where there are polar days and nights).

Tropics . Parallels 23.5°N sh. and 23.5°S sh. called tropical circles or just tropics. Above each of them once a year the midday Sun is at its zenith, those sunbeams fall vertically.

Fizminutka

III. Fixing the material.

Practical work:"Designation of illumination belts on contour maps of the hemispheres and Russia".

IV. Homework: III § 43; tasks in the textbook.

V. Additional material (if there is time left in the lesson)

seasons in poetry. N. Nekrasov

Winter.

It is not the wind that rages over the forest.

Streams did not run from the mountains,

Frost-voivode patrol

Bypasses his possessions.

Looks - good blizzards

Forest paths brought

And are there any cracks, cracks,

Is there any bare ground anywhere?A. Pushkin

Spring.

Chased by spring rays, .- "

There is already snow from the surrounding mountains

Escaped by muddy streams

To flooded meadows.

Nature's clear smile

Through a dream meets the morning of the year ...

BUT. Maykov

Smells like hay over the meadows...

Cheerful soul in song

Women with rakes in rows

They walk, moving hay ...A. Pushkin

There are two main mechanisms in heating the Earth by the Sun: 1) solar energy is transmitted through the world space in the form of radiant energy; 2) the radiant energy absorbed by the Earth is converted into heat.

The amount of solar radiation received by the Earth depends on:

from the distance between the earth and the sun. Earth is closest to the Sun in early January, farthest in early July; the difference between these two distances is 5 million km, as a result of which, in the first case, the Earth receives 3.4% more, and in the second 3.5% less radiation than with an average distance from the Earth to the Sun (in early April and at the beginning of October);

on the angle of incidence of the sun's rays on the earth's surface, which in turn depends on the geographic latitude, the height of the Sun above the horizon (changing during the day and seasons), the nature of the relief of the earth's surface;

from the conversion of radiant energy in the atmosphere (scattering, absorption, reflection back into space) and on the surface of the Earth. The average albedo of the Earth is 43%.

The picture of the annual heat balance by latitudinal zones (in calories per 1 sq. cm per 1 min.) Is presented in table II.

Absorbed radiation decreases towards the poles, while long-wave radiation practically does not change. The temperature contrasts that arise between low and high latitudes are softened by the transfer of heat by sea and mainly air currents from low to high latitudes; the amount of transferred heat is indicated in the last column of the table.

For general geographic conclusions, rhythmic fluctuations in radiation due to the change of seasons are also important, since the rhythm of the thermal regime in a particular area also depends on this.

According to the characteristics of the Earth's irradiation at different latitudes, it is possible to outline the "rough" contours of the thermal zones.

In the belt enclosed between the tropics, the rays of the Sun at noon fall all the time at a high angle. The sun is at its zenith twice a year, the difference in the length of day and night is small, the influx of heat in the year is large and relatively uniform. This is a hot belt.

Between the poles and the polar circles, day and night can last more than a day separately. On long nights (in winter) there is a strong cooling, since there is no heat influx at all, but even on long days (in summer) the heating is insignificant due to the low position of the Sun above the horizon, the reflection of radiation by snow and ice and the waste of heat on melting snow and ice. This is the cold belt.

Temperate zones are located between the tropics and the polar circles. Since the Sun is high in summer and low in winter, temperature fluctuations are quite large throughout the year.

However, in addition to geographic latitude (hence, solar radiation), the distribution of heat on Earth is also influenced by the nature of the distribution of land and sea, relief, altitude above sea level, sea and air currents. If these factors are also taken into account, then the boundaries of the thermal zones cannot be combined with parallels. That is why isotherms are taken as boundaries: annual - to highlight the zone in which the annual amplitudes of air temperature are small, and the isotherms of the warmest month - to highlight those zones where temperature fluctuations are sharper during the year. According to this principle, the following thermal zones are distinguished on Earth:

1) warm or hot, bounded in each hemisphere by an annual +20° isotherm passing near the 30th north and 30th south parallels;

2-3) two temperate zones, which in each hemisphere lie between the +20° annual isotherm and the +10° isotherm of the warmest month (July or January, respectively); in Death Valley (California) the highest July temperature on the globe was + 56.7 °;

4-5) two cold zones, in which the average temperature of the warmest month in the given hemisphere is less than +10°; sometimes two areas of eternal frost are distinguished from the cold belts with an average temperature of the warmest month below 0 °. In the northern hemisphere, this is the interior of Greenland and possibly the space near the pole; in the southern hemisphere, everything that lies south of the 60th parallel. Antarctica is especially cold; Here, in August 1960, at Vostok station, the lowest air temperature on Earth, -88.3°C, was recorded.

The relationship between the distribution of temperature on Earth and the distribution of incoming solar radiation is quite clear. However, a direct relationship between the decrease in the average values ​​of incoming radiation and the decrease in temperature with increasing latitude exists only in winter. In summer, for several months in the region of the North Pole, due to the longer day length here, the amount of radiation is noticeably higher than at the equator (Fig. 2). If the temperature distribution in summer corresponded to the distribution of radiation, then the summer air temperature in the Arctic would be close to tropical. This is not possible only because there is an ice cover in the polar regions (snow albedo in high latitudes reaches 70-90% and a lot of heat is spent on melting snow and ice). In its absence in the Central Arctic, the summer temperature would be 10-20°C, winter 5-10°C, i.e. a completely different climate would have formed, in which the Arctic islands and coasts could be dressed with rich vegetation, if many days and even many months of polar nights (the impossibility of photosynthesis) did not prevent this. The same would have happened in Antarctica, only with shades of "continentality": summers would be warmer than in the Arctic (closer to tropical conditions), winters would be colder. Therefore, the ice cover of the Arctic and Antarctic is more of a cause than a consequence of low temperatures at high latitudes.

These data and considerations, without violating the actual, observed regularity of the zonal distribution of heat on the Earth, pose the problem of the genesis of thermal belts in a new and somewhat unexpected context. It turns out, for example, that glaciation and climate are not a consequence and a cause, but two different consequences of one common cause: some change in natural conditions causes glaciation, and already under the influence of the latter, decisive changes in climate occur. And yet, at least local climate change must precede glaciation, because for the existence of ice, quite certain conditions of temperature and humidity are needed. A local ice mass can affect the local climate, allowing it to grow, then change the climate of a larger area, giving it an incentive to grow further, and so on. When such a spreading "ice lichen" (Gernet's term) covers a huge area, it will lead to a radical change in the climate in this area.

With the help of this video tutorial, you can independently study the topic "Distribution of sunlight and heat." First, discuss what determines the change of seasons, study the scheme of the annual rotation of the Earth around the Sun, paying special attention to the most remarkable four dates in terms of illumination by the Sun. Then you will find out what determines the distribution of sunlight and heat on the planet and why this happens unevenly.

Rice. 2. Illumination of the Earth by the Sun ()

In winter, the southern hemisphere of the Earth is better illuminated, in summer - the northern one.

Rice. 3. Scheme of the annual rotation of the Earth around the Sun

Solstice (summer solstice and winter solstice) - the times when the height of the Sun above the horizon at noon is greatest (summer solstice, June 22) or least (winter solstice, December 22). In the southern hemisphere, the opposite is true. On June 22, in the northern hemisphere, the greatest illumination by the Sun is observed, the day is longer than the night, and the polar day is observed beyond the polar circles. In the southern hemisphere, again, the opposite is true (i.e., all this is typical for December 22).

Arctic Circles (Arctic Circle and Antarctic Circle) - the parallels respectively with north and south latitude are about 66.5 degrees. North of the Arctic Circle and south of the Antarctic Circle, polar day (summer) and polar night (winter) are observed. The area from the Arctic Circle to the Pole in both hemispheres is called the Arctic. polar day - the period when the sun at high latitudes around the clock does not fall below the horizon.

polar night - the period when the Sun does not rise above the horizon at high latitudes around the clock - a phenomenon opposite to the polar day, is observed simultaneously with it at the corresponding latitudes of the other hemisphere.

Rice. 4. Scheme of the illumination of the Earth by the Sun by zones ()

Equinox (spring equinox and autumn equinox) - moments when the sun's rays touch both poles, and fall vertically on the equator. The spring equinox occurs on March 21st and the autumnal equinox occurs on September 23rd. These days, both hemispheres are equally lit, the day is equal to the night,

The main reason for the change in air temperature is the change in the angle of incidence of the sun's rays: the more sheer they fall on the earth's surface, the better they warm it.

Rice. 5. The angles of incidence of the sun's rays (at the position of the Sun 2, the rays warm the earth's surface better than at position 1) ()

On June 22, the sun's rays most sheer fall on the northern hemisphere of the Earth, thereby warming it to the greatest extent.

Tropics - The Northern Tropic and the Southern Tropic are parallels respectively with northern and southern latitudes of about 23.5 degrees. On one of the days of the solstice, the Sun at noon is above them at its zenith.

The tropics and polar circles divide the Earth into zones of illumination. Belts of illumination - parts of the Earth's surface bounded by the tropics and the polar circles and differing in lighting conditions. The warmest illumination zone is tropical, the coldest is polar.

Rice. 6. Belts of illumination of the Earth ()

The sun is the main luminary, the position of which determines the weather on our planet. The moon and other cosmic bodies have an indirect influence.

Salekhard is located on the line of the Arctic Circle. In this city, an obelisk to the Arctic Circle is installed.

Rice. 7. Obelisk to the Arctic Circle ()

Cities where you can watch the polar night: Murmansk, Norilsk, Monchegorsk, Vorkuta, Severomorsk, etc.

Homework

Section 44.

1. Name the days of the solstice and the days of the equinox.

Bibliography

Main

1. Initial course of geography: textbook. for 6 cells. general education institutions / T.P. Gerasimova, N.P. Neklyukov. - 10th ed., stereotype. - M.: Bustard, 2010. - 176 p.

2. Geography. Grade 6: atlas. - 3rd ed., stereotype. - M.: Bustard; DIK, 2011. - 32 p.

3. Geography. Grade 6: atlas. - 4th ed., stereotype. - M.: Bustard, DIK, 2013. - 32 p.

4. Geography. 6 cells: cont. maps: M.: DIK, Drofa, 2012. - 16 p.

Encyclopedias, dictionaries, reference books and statistical collections

1. Geography. Modern illustrated encyclopedia / A.P. Gorkin. - M.: Rosmen-Press, 2006. - 624 p.

Literature for preparing for the GIA and the Unified State Examination

1. Geography: Initial course: Tests. Proc. allowance for students 6 cells. - M.: Humanit. ed. center VLADOS, 2011. - 144 p.

2. Tests. Geography. Grades 6-10: Teaching aid / A.A. Letyagin. - M .: LLC "Agency" KRPA "Olimp": "Astrel", "AST", 2001. - 284 p.

1. Federal Institute of Pedagogical Measurements ().

2. Russian Geographical Society ().

3. Geografia.ru ().

Atmosphere pressure- the pressure of atmospheric air on the objects in it and the earth's surface. Normal atmospheric pressure is 760 mm Hg. Art. (101325 Pa). For each kilometer increase in altitude, the pressure drops by 100 mm.

The composition of the atmosphere:

The atmosphere of the Earth is the air shell of the Earth, consisting mainly of gases and various impurities (dust, water drops, ice crystals, sea salts, combustion products), the amount of which is not constant. The main gases are nitrogen (78%), oxygen (21%) and argon (0.93%). The concentration of gases that make up the atmosphere is almost constant, with the exception of carbon dioxide CO2 (0.03%).

The atmosphere also contains SO2, CH4, NH3, CO, hydrocarbons, HC1, HF, Hg vapor, I2, as well as NO and many other gases in small quantities. In the troposphere there is constantly a large amount of suspended solid and liquid particles (aerosol).

Climate and weather

Weather and climate are interrelated, but it's worth defining the difference between them.

Weather is the state of the atmosphere over a particular area at a particular point in time. In the same city, the weather can change every few hours: fog appears in the morning, a thunderstorm begins in the afternoon, and by the evening the sky is cleared of clouds.

Climate- a long-term, repetitive weather pattern characteristic of a particular area. The climate affects the terrain, water bodies, flora and fauna.

The main elements of the weather are precipitation (rain, snow, fog), wind, air temperature and humidity, and cloudiness.

Precipitation It is water in liquid or solid form that falls to the surface of the earth.

They are measured using a device called a rain gauge. This is a metal cylinder with a cross-sectional area of ​​​​500 cm2. Precipitation is measured in millimeters - this is the depth of the water layer that appeared in the rain gauge after precipitation.

Air temperature is determined using a thermometer - a device consisting of a temperature scale and a cylinder partially filled with a certain substance (usually alcohol or mercury). The action of a thermometer is based on the expansion of a substance when heated and compression - when cooled. One of the varieties of the thermometer is the well-known thermometer, in which the cylinder is filled with mercury. A thermometer that measures air temperature should be in the shade so that the sun's rays do not heat it up.

Temperature measurement is carried out at meteorological stations several times a day, after which the average daily, average monthly or average annual temperature is displayed.

The average daily temperature is the arithmetic mean of the temperatures measured at regular intervals during the day. The average monthly temperature is the arithmetic average of all average daily temperatures during the month, and the average annual temperature is the arithmetic average of all average daily temperatures during the year. In one locality, the average temperatures of each month and year remain approximately constant, since any large temperature fluctuations are leveled out by averaging. Currently, there is a trend towards a gradual increase in average temperatures, this phenomenon is called global warming. An increase in average temperature by a few tenths of a degree is imperceptible to humans, but it has a significant impact on the climate, since pressure and air humidity change along with temperature, as well as winds.

Air humidity shows how saturated it is with water vapor. Measure absolute and relative humidity. Absolute humidity is the amount of water vapor in 1 cubic meter of air, measured in grams. When talking about the weather, relative humidity is often used, which shows the percentage of water vapor in the air to the amount that is in the air at saturation. Saturation is a certain limit to which water vapor is in the air without condensing. Relative humidity cannot be more than 100%.

The saturation limit is different in different regions of the globe. Therefore, to compare humidity in different areas, it is better to use an absolute indicator of humidity, and to characterize the weather in a particular area - a relative indicator.

Cloudiness usually estimated using the following expressions: cloudy - the whole sky is covered with clouds, partly cloudy - there are a large number of individual clouds, clear - there are few or no clouds.

Atmosphere pressure- a very important characteristic of the weather. Atmospheric air has its own weight, and a column of air presses on every point on the earth's surface, on every object and living being on it. Atmospheric pressure is usually measured in millimeters of mercury. To make this measurement clear, let us explain what it means. Air presses on every square centimeter of the surface with the same force as a column of mercury 760 mm high. Thus, the air pressure is compared with the pressure of the mercury column. A number less than 760 means low blood pressure.

Temperature fluctuations

The temperature varies from place to place. At night, due to the lack of solar energy, the temperature drops. In this regard, it is customary to distinguish the average day and night temperatures. The temperature also fluctuates throughout the year. In winter, the average daily temperature is lower, gradually increasing in spring and gradually decreasing in autumn, in summer - the highest average daily temperature.

Distribution of light, heat and moisture over the Earth's surface

On the surface of the spherical Earth, solar heat and light are distributed unevenly. This is due to the fact that the angle of incidence of rays at different latitudes is different.

The earth's axis is inclined to the plane of the orbit at an angle. Its northern end is directed towards the North Star. The sun always illuminates half of the Earth. At the same time, the Northern Hemisphere is more illuminated (and the day there lasts longer than in the other hemisphere), then, on the contrary, the Southern Hemisphere. Twice a year, both hemispheres are equally illuminated (then the length of the day in both hemispheres is the same).

The sun is the main source of heat and light on Earth. This huge ball of gas with a surface temperature of about 6000 ° C radiates a large amount of energy, which is called solar radiation. It heats our Earth, sets the air in motion, forms the water cycle, creates conditions for the life of plants and animals.

Passing through the atmosphere, part of the solar radiation is absorbed, part is scattered and reflected. Therefore, the flow of solar radiation, coming to the surface of the Earth, gradually weakens.

Solar radiation arrives at the Earth's surface directly and diffusely. Direct radiation is a stream of parallel rays coming directly from the disk of the Sun. Scattered radiation comes from all over the sky. It is believed that the heat input from the Sun per 1 hectare of the Earth is equivalent to burning almost 143 thousand tons of coal.

The sun's rays, passing through the atmosphere, heat it up a little. The heating of the atmosphere comes from the surface of the Earth, which, absorbing solar energy, turns it into heat. Air particles, in contact with a heated surface, receive heat and carry it away into the atmosphere. This heats up the lower layers of the atmosphere. Obviously, the more the Earth's surface receives solar radiation, the more it heats up, the more the air heats up from it.

Numerous observations of air temperature showed that the highest temperature was observed in Tripoli (Africa) (+58°С), the lowest - at Vostok station in Antarctica (-87.4°С).

The influx of solar heat and the distribution of air temperature depends on the latitude of the place. The tropical region receives more heat from the Sun than the temperate and polar latitudes. The most heat is received by the equatorial regions of the Sun - the star of the solar system, which is the source of a huge amount of heat and dazzling light for the planet Earth. Despite the fact that the Sun is at a considerable distance from us and only a small part of its radiation reaches us, this is quite enough for the development of life on Earth. Our planet revolves around the sun in an orbit. If the Earth is observed from a spacecraft during the year, then one can notice that the Sun always illuminates only one half of the Earth, therefore, there will be day there, and at that time there will be night on the opposite half. The earth's surface receives heat only during the day.

Our Earth is heating unevenly. The uneven heating of the Earth is explained by its spherical shape, so the angle of incidence of the sun's ray in different areas is different, which means that different parts of the Earth receive different amounts of heat. At the equator, the sun's rays fall vertically, and they strongly heat the Earth. The farther from the equator, the angle of incidence of the beam becomes smaller, and consequently, these territories receive less heat. The same power beam of solar radiation heats a much smaller area near the equator, since it falls vertically. In addition, rays falling at a smaller angle than at the equator - penetrating the atmosphere, travel a longer path in it, as a result of which part of the sun's rays are scattered in the troposphere and do not reach the earth's surface. All this indicates that as you move away from the equator to the north or south, the air temperature decreases, as the angle of incidence of the sun's beam decreases.

The distribution of precipitation on the globe depends on how many clouds containing moisture form over a given area or how many of them the wind can bring. Air temperature is very important, because intensive evaporation of moisture occurs precisely at high temperatures. Moisture evaporates, rises up and clouds form at a certain height.

The air temperature decreases from the equator to the poles, therefore, the amount of precipitation is maximum in equatorial latitudes and decreases towards the poles. However, on land, the distribution of precipitation depends on a number of additional factors.

There is a lot of precipitation over coastal areas, and as you move away from the oceans, their amount decreases. There is more precipitation on the windward slopes of the mountain ranges and much less on the leeward slopes. For example, on the Atlantic coast of Norway, Bergen receives 1730 mm of precipitation per year, while Oslo receives only 560 mm. Low mountains also affect the distribution of precipitation - on the western slope of the Urals, in Ufa, an average of 600 mm of precipitation falls, and on the eastern slope, in Chelyabinsk, - 370 mm.

The greatest amount of precipitation falls in the Amazon basin, off the coast of the Gulf of Guinea and in Indonesia. In some areas of Indonesia, their maximum values ​​reach 7000 mm per year. In India, in the foothills of the Himalayas at an altitude of about 1300 m above sea level, there is the rainiest place on Earth - Cherrapunji (25.3 ° N and 91.8 ° E, an average of more than 11,000 mm of precipitation falls here in Such an abundance of moisture is brought to these places by the humid summer southwest monsoon, which rises along the steep slopes of the mountains, cools and pours with powerful rain.

The oceans, whose water temperature changes much more slowly than the temperature of the earth's surface or air, have a strong moderating effect on the climate. At night and in winter, the air over the oceans cools much more slowly than over land, and if oceanic air masses move over the continents, this leads to warming. Conversely, during the day and summer, the sea breeze cools the land.

The distribution of moisture on the earth's surface is determined by the water cycle in nature. Every second, a huge amount of water evaporates into the atmosphere, mainly from the surface of the oceans. Humid oceanic air, rushing over the continents, cools. The moisture then condenses and returns to the earth's surface in the form of rain or snow. Part of it is stored in the snow cover, rivers and lakes, and part returns to the ocean, where evaporation occurs again. This completes the hydrological cycle.

The distribution of precipitation is also influenced by the currents of the oceans. Over areas near which warm currents pass, the amount of precipitation increases, since the air heats up from warm water masses, it rises and clouds with sufficient water content form. Over the territories near which cold currents pass, the air cools down, falls down, clouds do not form, and much less precipitation falls.

Since water plays a significant role in erosion processes, it thereby affects the movements of the earth's crust. And any redistribution of masses due to such movements in the conditions of the Earth rotating around its axis can, in turn, contribute to a change in the position of the earth's axis. During ice ages, sea levels drop as water accumulates in glaciers. This, in turn, leads to the growth of continents and an increase in climatic contrasts. Reducing river flow and lowering sea levels prevent warm ocean currents from reaching cold regions, leading to further climate change.

Video lesson 2: Atmosphere structure, meaning, study

Lecture: Atmosphere. Composition, structure, circulation. Distribution of heat and moisture on the Earth. Weather and climate

Atmosphere

atmosphere can be called an all-pervading shell. Its gaseous state allows filling microscopic holes in the soil, water is dissolved in water, animals, plants and humans cannot exist without air.

The nominal thickness of the shell is 1500 km. Its upper boundaries dissolve into space and are not clearly marked. Atmospheric pressure at sea level at 0°C is 760 mm. rt. Art. The gas envelope is 78% nitrogen, 21% oxygen, 1% other gases (ozone, helium, water vapor, carbon dioxide). The density of the air shell changes with elevation: the higher, the rarer the air. This is why climbers can be oxygen starved. At the very surface of the earth, the highest density.

Composition, structure, circulation

Layers are distinguished in the shell:

Troposphere, 8-20 km thick. Moreover, at the poles the thickness of the troposphere is less than at the equator. About 80% of the total air mass is concentrated in this small layer. The troposphere tends to heat up from the surface of the earth, so its temperature is higher near the earth itself. With a rise up to 1 km. the temperature of the air envelope decreases by 6°C. In the troposphere, there is an active movement of air masses in the vertical and horizontal direction. It is this shell that is the "factory" of the weather. Cyclones and anticyclones form in it, westerly and easterly winds blow. All water vapor is concentrated in it, which condense and shed rain or snow. This layer of the atmosphere contains impurities: smoke, ash, dust, soot, everything we breathe. The boundary layer with the stratosphere is called the tropopause. Here the temperature drop ends.

Approximate boundaries stratosphere 11-55 km. Up to 25 km. There are slight changes in temperature, and higher it begins to rise from -56°C to 0°C at an altitude of 40 km. For another 15 kilometers, the temperature does not change, this layer was called the stratopause. The stratosphere in its composition contains ozone (O3), a protective barrier for the Earth. Due to the presence of the ozone layer, harmful ultraviolet rays do not penetrate the earth's surface. Recently, anthropogenic activity has led to the destruction of this layer and the formation of "ozone holes". Scientists say that the cause of the "holes" is an increased concentration of free radicals and freon. Under the influence of solar radiation, the molecules of gases are destroyed, this process is accompanied by a glow (northern lights).

From 50-55 km. next layer starts mesosphere, which rises to 80-90 km. In this layer, the temperature decreases, at an altitude of 80 km it is -90°C. In the troposphere, the temperature again rises to several hundred degrees. Thermosphere extends up to 800 km. Upper bounds exosphere are not determined, since the gas dissipates and partially escapes into outer space.

Heat and moisture

The distribution of solar heat on the planet depends on the latitude of the place. The equator and the tropics receive more solar energy, since the angle of incidence of the sun's rays is about 90 °. The closer to the poles, the angle of incidence of the rays decreases, respectively, the amount of heat also decreases. The sun's rays, passing through the air shell, do not heat it. Only when it hits the ground, the sun's heat is absorbed by the surface of the earth, and then the air is heated from the underlying surface. The same thing happens in the ocean, except that water heats up more slowly than land and cools more slowly. Therefore, the proximity of the seas and oceans has an impact on climate formation. In summer, sea air brings us coolness and precipitation, in winter warming, since the surface of the ocean has not yet spent its heat accumulated over the summer, and the earth's surface has quickly cooled down. Marine air masses form above the surface of the water, therefore, they are saturated with water vapor. Moving over land, air masses lose moisture, bringing precipitation. Continental air masses form above the surface of the earth, as a rule, they are dry. The presence of continental air masses brings hot weather in summer, and clear frosty weather in winter.

Weather and climate

Weather- the state of the troposphere in a given place for a certain period of time.

Climate- the long-term weather regime characteristic of the area.

The weather can change during the day. Climate is a more constant characteristic. Each physical-geographical region is characterized by a certain type of climate. The climate is formed as a result of the interaction and mutual influence of several factors: the latitude of the place, the prevailing air masses, the relief of the underlying surface, the presence of underwater currents, the presence or absence of water bodies.

On the earth's surface there are belts of low and high atmospheric pressure. Equatorial and temperate zones of low pressure, high pressure at the poles and in the tropics. Air masses move from an area of ​​high pressure to an area of ​​low pressure. But as our Earth rotates, these directions deviate, in the northern hemisphere to the right, in the southern hemisphere to the left. Trade winds blow from the tropics to the equator, westerly winds blow from the tropics to the temperate zone, and polar easterly winds blow from the poles to the temperate zone. But in each belt, land areas alternate with water areas. Depending on whether the air mass formed over land or over the ocean, it can bring heavy rains or a clear sunny surface. The amount of moisture in air masses is affected by the topography of the underlying surface. Moisture-saturated air masses pass over the flat territories without obstacles. But if there are mountains on the way, the heavy moist air cannot move through the mountains, and is forced to lose some, if not all, of the moisture on the slopes of the mountains. The east coast of Africa has a mountainous surface (Dragon Mountains). The air masses that form over the Indian Ocean are saturated with moisture, but all the water is lost on the coast, and a hot dry wind comes inland. That is why most of southern Africa is occupied by deserts.