Change in air temperature with height. The atmosphere of the earth and the physical properties of air What is the temperature at an altitude of 150 km
inversion
increase in air temperature with height instead of the usual decrease
Alternative descriptions
An excited state of matter in which the number of particles at a higher energy. level exceeds the number of particles at a lower level (physics)
Change of direction magnetic field Earth on the reverse, observed at time intervals from 500 thousand years to 50 million years
Changing the normal position of elements, placing them in reverse order
Linguistic term for changing the usual word order in a sentence
Reverse order, reverse order
Logical operation "not"
Chromosomal rearrangement associated with the rotation of individual sections of the chromosome by 180
Conformal transformation of the Euclidean plane or space
Permutation in mathematics
A dramatic device that demonstrates the outcome of the conflict at the beginning of the play
In metrology - abnormal change any parameter
The state of matter in which high levels the energies of its constituent particles are more "populated" by particles than the lower
AT organic chemistry- saccharide breakdown process
Changing the order of words in a sentence
Changing word order for emphasis
white trail behind the plane
Changing word order
Reverse order of elements
Changing the normal order of words in a sentence in order to enhance the expressiveness of speech
In the first sections, we met in general terms with the vertical structure of the atmosphere and with changes in temperature with altitude.
Here we consider some interesting features temperature regime in the troposphere and in the overlying spheres.
Temperature and humidity in the troposphere. The troposphere is the most interesting area, since rock-forming processes are formed here. In the troposphere, as already mentioned in Chapter I, the air temperature decreases with height by an average of 6° per kilometer of elevation, or by 0.6° per 100 m. This value of the vertical temperature gradient is observed most often and is defined as the average of many measurements. In fact, the vertical temperature gradient in temperate latitudes The earth is changeable. It depends on the seasons of the year, the time of day, the nature of atmospheric processes, and in the lower layers of the troposphere - mainly on the temperature of the underlying surface.
In the warm season, when the layer of air adjacent to the surface of the earth is sufficiently heated, a decrease in temperature with height is characteristic. With a strong heating of the surface layer of air, the value of the vertical temperature gradient exceeds even 1 ° for every 100 m uplift.
In winter, with a strong cooling of the surface of the earth and the surface layer of air, instead of lowering, an increase in temperature is observed with height, i.e., a temperature inversion occurs. The strongest and most powerful inversions are observed in Siberia, especially in Yakutia in winter, where clear and calm weather prevails, which contributes to the radiation and subsequent cooling of the surface air layer. Very often, the temperature inversion here extends to a height of 2-3 km, and the difference between the air temperature at the earth's surface and the upper boundary of the inversion is often 20-25°. Inversions are also characteristic of central regions Antarctica. In winter, they are in Europe, especially in its eastern part, Canada and other areas. The magnitude of the change in temperature with height (vertical temperature gradient) largely determines the weather conditions and types of air movement in the vertical direction.
Stable and unstable atmosphere. The air in the troposphere is heated by the underlying surface. Air temperature changes with height and with atmospheric pressure. When this happens without heat exchange with environment, then such a process is called adiabatic. Rising air does work at the expense of internal energy, which is spent on overcoming external resistance. Therefore, when it rises, the air cools, and when it descends, it heats up.
Adiabatic temperature changes occur according to dry adiabatic and wet adiabatic laws.
Accordingly, vertical gradients of temperature change with height are also distinguished. Dry adiabatic gradient is the change in temperature of dry or moist unsaturated air for every 100 m raise and lower it by 1 °, a wet adiabatic gradient is the decrease in temperature of moist saturated air for every 100 m elevation less than 1°.
When dry, or unsaturated, air rises or falls, its temperature changes according to the dry adiabatic law, i.e., respectively, falls or rises by 1 ° every 100 m. This value does not change until the air, when rising, reaches a state of saturation, i.e. condensation level water vapor. Above this level, due to condensation, the latent heat of vaporization begins to be released, which is used to heat the air. This additional heat reduces the amount of air cooling as it rises. A further rise in saturated air occurs already according to the humid adiabatic law, and its temperature does not decrease by 1 ° per 100 m, but less. Since the moisture content of air depends on its temperature, the higher the air temperature, the more heat is released during condensation, and the lower the temperature, the less heat. Therefore, the humid adiabatic gradient in warm air is smaller than in cold air. For example, at a temperature of rising saturated air near the earth's surface of +20°, the humid adiabatic gradient in the lower troposphere is 0.33-0.43° per 100 m, and at a temperature of minus 20° its values range from 0.78° to 0.87° per 100 m.
The wet adiabatic gradient also depends on the air pressure: the lower the air pressure, the smaller the wet adiabatic gradient at the same initial temperature. This is due to the fact that at low pressure, the air density is also less, therefore, the released heat of condensation is used to heat a smaller mass of air.
Table 15 shows the average values of the wet adiabatic gradient at various temperatures and values
pressure 1000, 750 and 500 mb, which approximately corresponds to the surface of the earth and heights of 2.5-5.5 km.
In the warm season, the vertical temperature gradient averages 0.6-0.7° per 100 m uplift.
Knowing the temperature at the surface of the earth, it is possible to calculate the approximate values of the temperature at various heights. If, for example, the air temperature at the earth's surface is 28°, then, assuming that the vertical temperature gradient is on average 0.7° per 100 m or 7° per kilometer, we get that at a height of 4 km the temperature is 0°. The temperature gradient in winter in the middle latitudes over land rarely exceeds 0.4-0.5 ° per 100 m: There are frequent cases when in separate layers of air the temperature almost does not change with height, i.e., isothermia takes place.
By the magnitude of the vertical air temperature gradient, one can judge the nature of the equilibrium of the atmosphere - stable or unstable.
At stable equilibrium atmospheric masses of air do not tend to move vertically. In this case, if a certain volume of air is shifted upwards, it will return to its original position.
Stable equilibrium occurs when the vertical temperature gradient of unsaturated air is less than the dry adiabatic gradient, and the vertical temperature gradient of saturated air is less than the wet adiabatic one. If, under this condition, a small volume of unsaturated air is raised by an external influence to a certain height, then as soon as the action stops external force, this volume of air will return to its previous position. This happens because the raised volume of air, having spent internal energy on its expansion, was cooled by 1 ° for every 100 m(according to the dry adiabatic law). But since the vertical temperature gradient of the ambient air was less than the dry adiabatic one, it turned out that the volume of air raised at a given height had a lower temperature than the ambient air. Having a greater density than the surrounding air, it must sink until it reaches its original state. Let's show this with an example.
Suppose that the air temperature near the earth's surface is 20°, and the vertical temperature gradient in the layer under consideration is 0.7° per 100 m. With this value of the gradient, the air temperature at a height of 2 km will be equal to 6° (Fig. 19, a). Under the influence of an external force, a volume of unsaturated or dry air raised from the surface of the earth to this height, cooling according to the dry adiabatic law, i.e., by 1 ° per 100 m, will cool by 20 ° and take a temperature equal to 0 °. This volume of air will be 6° colder than the surrounding air, and therefore heavier due to its greater density. So he starts
descend, trying to reach the initial level, i.e., the surface of the earth.
A similar result will be obtained in the case of rising saturated air, if the vertical gradient of the ambient temperature is less than the humid adiabatic one. Therefore, under a stable state of the atmosphere in a homogeneous mass of air, there is no rapid formation of cumulus and cumulonimbus clouds.
The most stable state of the atmosphere is observed at small values of the vertical temperature gradient, and especially during inversions, since in this case warmer and lighter air is located above the lower cold, and therefore heavy, air.
At unstable equilibrium of the atmosphere the volume of air raised from the earth's surface does not return to its original position, but retains its upward movement to a level at which the temperatures of the rising and surrounding air are equalized. The unstable state of the atmosphere is characterized by large vertical temperature gradients, which is caused by heating of the lower layers of air. At the same time, the air masses warmed up below, as lighter ones, rush upwards.
Suppose, for example, that unsaturated air in the lower layers up to a height of 2 km stratified unstable, i.e. its temperature
decreases with altitude by 1.2° for every 100 m, and above, the air, having become saturated, has a stable stratification, i.e., its temperature drops already by 0.6 ° for every 100 m uplifts (Fig. 19, b). Once in such an environment, the volume of dry unsaturated air will begin to rise according to the dry adiabatic law, i.e., it will cool by 1 ° per 100 m. Then, if its temperature near the earth's surface is 20°, then at a height of 1 km it will become 10°, while the ambient temperature is 8°. Being 2° warmer and therefore lighter, this volume will rush higher. At height 2 km it will be already 4° warmer than the environment, since its temperature will reach 0°, and the ambient temperature is -4°. Being lighter again, the considered volume of air will continue its rise to a height of 3 km, where its temperature becomes equal to the ambient temperature (-10 °). After that, the free rise of the allocated air volume will stop.
To determine the state of the atmosphere are used aerological charts. These are diagrams with rectangular coordinate axes, along which the characteristics of the state of the air are plotted.
Families are plotted on upper-air diagrams dry and wet adiabats, i.e., curves graphically representing the change in the state of air during dry adiabatic and wet adiabatic processes.
Figure 20 shows such a diagram. Here, isobars are shown vertically, isotherms (lines of equal air pressure) horizontally, inclined solid lines are dry adiabats, inclined dashed lines are wet adiabats, dashed lines are specific humidity.The above diagram shows curves of air temperature changes with a height of two points for the same observation period - 15:00 on May 3, 1965. On the left - the temperature curve according to the data of a radiosonde launched in Leningrad, on the right - in Tashkent. It follows from the shape of the left curve of temperature change with height that the air in Leningrad is stable. In this case, up to the isobaric surface of 500 mb the vertical temperature gradient averages 0.55° per 100 m. In two small layers (on surfaces 900 and 700 mb) isotherm was recorded. This indicates that over Leningrad at heights of 1.5-4.5 km located atmospheric front, separating cold air masses in the lower one and a half kilometers from thermal air located above. The height of the condensation level, determined by the position of the temperature curve with respect to the wet adiabat, is about 1 km(900 mb).
In Tashkent, the air had an unstable stratification. Up to height 4 km vertical temperature gradient was close to adiabatic, i.e., for every 100 m rise, the temperature decreased by 1 °, and higher, up to 12 km- more adiabatic. Due to the dryness of the air, cloud formation did not occur.
Over Leningrad, the transition to the stratosphere took place at an altitude of 9 km(300 mb), and over Tashkent it is much higher - about 12 km(200 mb).
With a stable state of the atmosphere and sufficient humidity, stratus clouds and fogs can form, and with an unstable state and a high moisture content of the atmosphere, thermal convection, leading to the formation of cumulus and cumulonimbus clouds. The state of instability is associated with the formation of showers, thunderstorms, hail, small whirlwinds, squalls, etc.
The so-called "chatter" of the aircraft, i.e., the throws of the aircraft during flight, is also caused by the unstable state of the atmosphere.
In summer, the instability of the atmosphere is common in the afternoon, when the layers of air close to the earth's surface are heated. Therefore, heavy rains, squalls and the like dangerous phenomena weather is more often observed in the afternoon, when strong vertical currents arise due to breaking instability - ascending and descending air movement. For this reason, aircraft flying during the day at an altitude of 2-5 km above the surface of the earth, they are more subject to "chatter" than during night flight, when, due to the cooling of the surface layer of air, its stability increases.
Humidity also decreases with altitude. Almost half of all humidity is concentrated in the first one and a half kilometers of the atmosphere, and the first five kilometers contain almost 9/10 of all water vapor.
To illustrate the daily observed nature of the change in temperature with height in the troposphere and lower stratosphere in different regions of the Earth, Figure 21 shows three stratification curves up to a height of 22-25 km. These curves were built from radiosonde observations at 3 pm: two in January - Olekminsk (Yakutia) and Leningrad, and the third in July - Takhta-Bazar ( middle Asia). The first curve (Olekminsk) is characterized by the presence of a surface inversion, characterized by an increase in temperature from -48° at the earth's surface to -25° at a height of about 1 km. During this period, the tropopause over Olekminsk was at a height of 9 km(temperature -62°). In the stratosphere, an increase in temperature with height was observed, the value of which is at the level of 22 km approached -50°. The second curve, representing the change in temperature with height in Leningrad, indicates the presence of a small surface inversion, then an isotherm in a large layer and a decrease in temperature in the stratosphere. At level 25 km the temperature is -75°. The third curve (Takhta-Bazar) is very different from the northern point - Olekminsk. The temperature at the earth's surface is above 30°. The tropopause is at 16 km, and above 18 km the usual for southern summer rise in temperature with height.
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The sun's rays falling on the surface of the earth heat it up. The air is heated from the bottom up, i.e. from the earth's surface.
The transfer of heat from the lower layers of air to the upper ones occurs mainly due to the rise of warm, heated air up and the lowering of cold air down. This process of heating air is called convection.
In other cases, the upward heat transfer occurs due to dynamic turbulence. This is the name of chaotic whirlwinds that arise in the air as a result of its friction against the earth's surface during horizontal movement or during the friction of different layers of air with each other.
Convection is sometimes called thermal turbulence. Convection and turbulence are sometimes combined common name - exchange.
The cooling of the lower layers of the atmosphere occurs differently than heating. The earth's surface continuously loses heat to its surrounding atmosphere by emitting heat rays that are not visible to the eye. Cooling becomes especially strong after sunset (at night). Due to thermal conductivity, the air masses adjacent to the ground also gradually cool, transferring this cooling to the overlying layers of air; at the same time, the lowest layers are most intensively cooled.
Depending on solar heating, the temperature of the lower layers of air changes during the year and day, reaching a maximum at about 13-14 hours. daily course air temperature in different days for one and the same place is inconsistent; its value depends mainly on the state of the weather. Thus, changes in the temperature of the lower layers of air are associated with changes in the temperature of the earth's (underlying) surface.
Changes in air temperature also occur from its vertical movements.
It is known that when air expands, it cools, and when compressed, it heats up. In the atmosphere during the upward movement of air, falling into areas of more low pressure, expands and cools, and, conversely, with a downward movement, the air, compressing, heats up. Changes in air temperature during its vertical movements largely determine the formation and destruction of clouds.
Air temperature usually decreases with altitude. Change average temperature with the height above Europe in summer and winter is given in the table "Average air temperatures over Europe". 
The decrease in temperature with height is characterized by a vertical temperature gradient. This is the change in temperature for every 100 m of altitude. For technical and aeronautical calculations, the vertical temperature gradient is assumed to be 0.6. It must be borne in mind that this value is not constant. It may happen that in any layer of air the temperature will not change with height.
Such layers are called layers of isotherm.
Quite often, a phenomenon is observed in the atmosphere when, in a certain layer, the temperature even increases with height. These layers of the atmosphere are called inversion layers. Inversions arise from various reasons. One of them is the cooling of the underlying surface by radiation at night or winter time under a clear sky. Sometimes, in the case of calm or light winds, the surface layers of air also cool and become colder than the overlying layers. As a result, the air at altitude is warmer than at the bottom. Such inversions are called radiation. Strong radiative inversions are usually observed over the snow cover and especially in mountain basins, and also during calm. The inversion layers extend up to a height of several tens or hundreds of meters.
Inversions also arise due to the movement (advection) of warm air onto the cold underlying surface. These are the so-called advective inversions. The height of these inversions is several hundred meters.
In addition to these inversions, frontal inversions and compression inversions are observed. Frontal inversions occur when warm air masses flow onto colder air masses. Compression inversions occur when air descends from the upper atmosphere. At the same time, the descending air is sometimes heated so much that its underlying layers turn out to be colder.
Temperature inversions are observed at various heights of the troposphere, most often at altitudes of about 1 km. The thickness of the inversion layer can vary from several tens to several hundreds of meters. The temperature difference during inversion can reach 15-20°.
Layers of inversions play big role in the weather. Because the air in the inversion layer is warmer than the underlying layer, the air from the lower layers cannot rise. Consequently, layers of inversions retard vertical movements in the underlying air layer. When flying under a layer of inversion, a rheme ("bumpiness") is usually observed. Above the inversion layer, the flight of the aircraft usually proceeds normally. So-called wavy clouds develop under the layers of inversions.
The air temperature affects the piloting technique and the operation of the materiel. At temperatures near the ground below -20 °, the oil freezes, so it has to be filled in in a heated state. In flight at low temperatures the water in the cooling system of the motor is intensively cooled. At elevated temperatures (above + 30 °), the motor may overheat. Air temperature also affects the performance of the aircraft crew. At low temperatures, reaching up to -56 ° in the stratosphere, special uniforms are required for the crew.
The air temperature is very great importance for weather forecast.
Measurement of air temperature during the flight on an aircraft is carried out using electric thermometers attached to the aircraft. When measuring air temperature, it must be borne in mind that due to the high speeds of modern aircraft, thermometers give errors. The high speeds of the aircraft cause an increase in the temperature of the thermometer itself, due to the friction of its reservoir against the air and the effect of heating due to air compression. Friction heating increases with an increase in aircraft flight speed and is expressed by the following quantities:
Speed in km/h …………. 100 200 Z00 400 500 600
Friction heating ……. 0°.34 1°.37 3°.1 5°.5 8°.6 12°,b
Heating from compression is expressed by the following quantities:
Speed in km/h …………. 100 200 300 400 500 600
Heating by compression ……. 0°.39 1°.55 3°.5 5°.2 9°.7 14°.0
Distortions in the readings of a thermometer installed on an airplane, when flying in clouds, are 30% less than the above values, due to the fact that part of the heat that occurs during friction and compression is spent on the evaporation of water condensed in the air in the form of droplets.
Air temperature. Units of measure, change in temperature with altitude. Inversion, isothermy, Types of inversions, Adiabatic process.
Air temperature is a value that characterizes its thermal state. It is expressed either in degrees Celsius (ºС on a centigrade scale or in Kelvin (K) on an absolute scale. The transition from temperature in Kelvin to temperature in degrees Celsius is performed by the formula
t=T-273º
The lower layer of the atmosphere (troposphere) is characterized by a decrease in temperature with height, amounting to 0.65ºС per 100 m.
This change in temperature with height per 100m is called the vertical temperature gradient. Knowing the temperature near the earth's surface and using the value of the vertical gradient, it is possible to calculate the approximate temperature at any height (for example, at a temperature near the earth's surface of +20ºС at a height of 5000m, the temperature will be equal to:
20º- (0.65 * 50) \u003d - 12..5.
The vertical gradient γ is not constant and depends on the type air mass, time of day and season of the year, the nature of the underlying surface and other reasons. When the temperature decreases with height, γ is considered positive, if the temperature does not change with height, then γ = 0 the layers are called isothermal. Atmospheric layers where the temperature rises with height (γ< 0), называются inversion. Depending on the magnitude of the vertical temperature gradient, the state of the atmosphere can be stable, unstable, or indifferent to dry (not saturated) or saturated air.
The decrease in air temperature as it rises adiabatically, that is, without heat exchange of air particles with the environment. If an air particle rises, then its volume expands, while the internal energy of the particle decreases.
As the particle descends, it contracts and its internal energy increases. From this it follows that with an upward movement of the volume of air, its temperature decreases, and with a downward movement, it rises. These processes play an important role in the formation and development of clouds.
The horizontal gradient is the temperature expressed in degrees at a distance of 100 km. During the transition from cold to warm VM and from warm to cold, it can exceed 10º per 100 km.
Types of inversions.
Inversions are delay layers, they dampen vertical air movements, under them there is an accumulation of water vapor or other solid particles that impair visibility, fog and various forms clouds. The layers of inversions are decelerating layers for horizontal air movements as well. In many cases, these layers are wind break surfaces. Inversions in the troposphere can be observed near the earth's surface and at high altitudes. The tropopause is a powerful layer of inversion.
Depending on the causes of occurrence, the following types of inversions are distinguished:
1. Radiation - the result of cooling the surface layer of air, usually at night.
2. Advective - when warm air moves to a cold underlying surface.
3. Compression or lowering - formed in central parts immobile anticyclones.
Troposphere
Its upper limit is at an altitude of 8-10 km in polar, 10-12 km in temperate and 16-18 km in tropical latitudes; lower in winter than in summer. The lower, main layer of the atmosphere contains more than 80% of the total mass atmospheric air and about 90% of all water vapor in the atmosphere. In the troposphere, turbulence and convection are highly developed, clouds appear, cyclones and anticyclones develop. Temperature decreases with altitude with an average vertical gradient of 0.65°/100 m
tropopause
The transitional layer from the troposphere to the stratosphere, the layer of the atmosphere in which the decrease in temperature with height stops.
Stratosphere
The layer of the atmosphere located at an altitude of 11 to 50 km. A slight change in temperature in the 11-25 km layer (the lower layer of the stratosphere) and its increase in the 25-40 km layer from -56.5 to 0.8 °C (the upper stratosphere layer or inversion region) are typical. Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and the mesosphere.
Stratopause
The boundary layer of the atmosphere between the stratosphere and the mesosphere. There is a maximum in the vertical temperature distribution (about 0 °C).
Mesosphere
The mesosphere begins at an altitude of 50 km and extends up to 80-90 km. The temperature decreases with height with an average vertical gradient of (0.25-0.3) ° / 100 m. energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc., cause atmospheric luminescence.
Mesopause
Transitional layer between mesosphere and thermosphere. There is a minimum in the vertical temperature distribution (about -90 °C).
Karman Line
Altitude above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space. The Karmana line is located at an altitude of 100 km above sea level.
Earth's atmosphere boundary
Thermosphere
The upper limit is about 800 km. The temperature rises to altitudes of 200-300 km, where it reaches values of the order of 1500 K, after which it remains almost constant up to high altitudes. Under the influence of ultraviolet and X-ray solar radiation and cosmic radiation, air is ionized (“ auroras”) - the main regions of the ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity, there is a noticeable decrease in the size of this layer.
Thermopause
The region of the atmosphere above the thermosphere. In this area absorption solar radiation insignificantly and the temperature does not actually change with altitude.
Exosphere (scattering sphere)
Atmospheric layers up to a height of 120 km
Exosphere - scattering zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and hence its particles leak into interplanetary space (dissipation).
Up to a height of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases in height depends on their molecular weights, the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0 °C in the stratosphere to −110 °C in the mesosphere. However kinetic energy individual particles at altitudes of 200–250 km corresponds to a temperature of ~150 °C. Above 200 km, significant fluctuations in temperature and gas density are observed in time and space.
At an altitude of about 2000-3500 km, the exosphere gradually passes into the so-called near space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas is only part of the interplanetary matter. The other part is composed of dust-like particles of cometary and meteoric origin. In addition to extremely rarefied dust-like particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.
The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere accounts for about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutrosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.
Depending on the composition of the gas in the atmosphere, homosphere and heterosphere are distinguished. The heterosphere is an area where gravity has an effect on the separation of gases, since their mixing at such a height is negligible. Hence follows the variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere, called the homosphere. The boundary between these layers is called the turbopause and lies at an altitude of about 120 km.
Public lesson
in natural history at 5
Change in air temperature from heights
Developed
teacher Shuvalova O.T.
The purpose of the lesson:
To form knowledge about measuring air temperature with height, to acquaint with the process of cloud formation, types of precipitation.
During the classes
Having a textbook workbook, diary, pens.
2. Checking students' knowledge
We are studying the topic: air
Before we start studying new material, let's recall the material covered, what do we know about air?
Frontal survey
Composition of air
Where do these gases come from in the air, nitrogen, oxygen, carbon dioxide, impurities.
Air property: occupies space, compressibility, elasticity.
Air weight?
Atmospheric pressure, its change with height.
Air heating.
3. Learning new material
We know that heated air rises. And what happens to the heated air further, do we know?
Do you think air temperature will decrease with altitude?
Lesson topic: change in air temperature with height.
The purpose of the lesson: to find out how air temperature changes with height and what are the results of these changes.
An excerpt from the book of the Swedish writer "Nils' wonderful journey with wild geese" about a one-eyed troll who decided "I will build a house closer to the sun - let it warm me." And the troll set to work. He collected stones everywhere and piled them on top of each other. Soon the mountain of their stones rose almost to the very clouds.
Now, that's enough! - said the troll. Now I will build myself a house on top of this mountain. I will live right next to the sun. I won't freeze next to the sun! And the troll went up the mountain. Just what is it? The higher it goes, the colder it gets. Made it to the top.
"Well - he thinks - from here to the sun is a stone's throw!". And at the very cold, the tooth does not fall on the tooth. This troll was stubborn: if it already sinks into his head, nothing can knock him out. I decided to build a house on the mountain, and built it. The sun seems to be close, but the cold still penetrates to the bones. So this stupid troll froze.
Explain why the stubborn troll froze.
Conclusion: the closer to the earth's surface the air, the warmer it is, and with height it becomes colder.
When climbing to a height of 1500m, the air temperature rises by 8 degrees. Therefore, outside the aircraft at an altitude of 1000m, the air temperature is 25 degrees, and at the surface of the earth at the same time the thermometer shows 27 degrees.
What is the matter here?
The lower layers of air, heating up, expand, reduce their density and, rising up, transfer heat to the upper layers of the atmosphere. This means that the heat coming from the surface of the earth is poorly conserved. That is why it does not become warmer, but colder overboard, which is why the stubborn troll froze.
Demonstration of the card: the mountains are low and high.
What differences do you see?
Why are the tops of high mountains covered with snow, but there is no snow at the foot of the mountains? The appearance of glaciers and eternal snows on the tops of mountains is associated with a change in air temperature with height, the climate becomes more severe, and accordingly changes vegetable world. At the very top, near the high mountain peaks, there is a realm of cold, snow and ice. Mountain peaks and in the tropics are covered with eternal snow. The boundaries of eternal snow in the mountains are called the snow line.
Demonstration of the table: mountains.
Look at the card with the image of various mountains. Is the height of the snow line the same everywhere? What is it connected with? The height of the snow line is different. AT northern regions it is lower, and in the south it is higher. This line is not drawn on the mountain. How can we define the concept of "snow line".
The snow line is the line above which the snow does not melt even in summer. Below the snow line there is a zone characterized by sparse vegetation, then there is a regular change in the composition of the vegetation as it approaches the foot of the mountain.
What do we see in the sky every day?
Why do clouds form in the sky?
As the heated air rises, it carries water vapor that is not visible to the eye into a higher layer of the atmosphere. As the air moves away from the earth's surface, the air temperature drops, the water vapor in it cools, and tiny droplets of water form. Their accumulation leads to the formation of a cloud.
TYPES OF CLOUD:
Cirrus
layered
Cumulus
Demonstration of a card with types of clouds.
Cirrus clouds are the tallest and thinnest. They swim very high above the ground, where it is always cold. These are beautiful and cold clouds. shines through them blue sky. They look like long feathers of fabulous birds. Therefore, they are called cirrus.
Stratus clouds are solid, pale gray. They cover the sky with a monotonous gray veil. Such clouds bring bad weather: snow, drizzling rain for several days.
Rain cumulus clouds - large and dark, they rush one after another as if in a race. Sometimes the wind carries them so low that it seems that the clouds touch the roofs.
Rare cumulus clouds are the most beautiful. They resemble mountains with dazzling white peaks. And they are interesting to watch. Cheerful cumulus clouds are running across the sky, constantly changing. They look either like animals, or like people, or like some kind of fabulous creatures.
Demonstration of the card various types clouds.
What clouds are shown in the pictures?
Under certain conditions of atmospheric air, precipitation falls from the clouds.
What kind of precipitation do you know?
Rain, snow, hail, dew and others.
The smallest droplets of water that make up the clouds, merging with each other, gradually increase, become heavy and fall to the ground. Summer it's raining, snow in winter.
What is snow made of?
Snow is made up of ice crystals. different shapes- snowflakes, mostly six-pointed stars, fall out of the clouds when the air temperature is below zero degrees.
Often in the warm season, during a downpour, hail falls - precipitation in the form of pieces of ice, most often of irregular shape.
How is hail formed in the atmosphere?
Droplets of water, falling to a great height, freeze, ice crystals grow on them. Falling down, they collide with drops of supercooled water and increase in size. The hail is capable of causing great damage. He knocks out crops, exposes forests, knocking down foliage, destroying birds.
4.Total lesson.
What new did you learn in the lesson about air?
1. Decrease in air temperature with height.
2. Snow line.
3. Types of precipitation.
5. Homework.
Learn the notes in your notebook. Observation of the clouds with a sketch of them in a notebook.
6. Consolidation of the past.
Independent work with text. Fill in the gaps in the text using the words for reference.
Air temperature change with height
Exercise 1. Determine what temperature the air mass will have, not saturated with water vapor and rising adiabatically at a height of 500, 1000, 1500 m, if its temperature at the earth's surface was 15º.
The temperature changes by 1 ° when the air mass rises for every 100 m. This value is called dry adiabatic temperature gradient. When the air saturated with water vapor rises, the rate of its cooling decreases somewhat, since in this case water vapor condenses, during which the latent heat of vaporization (600 cal per 1 g of condensed water) is released, which is used to heat this rising air. The adiabatic process that occurs inside the rising saturated air is called wet adiabatic. The amount of decrease (increase) in temperature for every 100 m in the rising moist saturated air mass is called humid adiabatic temperature gradient r in , and the graph of temperature change with height in such a process is called wet adiabat. In contrast to the dry adiabatic gradient r a, the wet adiabatic gradient r v is a variable value depending on temperature and pressure, and lies in the range from 0.3° to 0.9° per 100 m of height (0.6° per 100 m on average). ). The more moisture condenses when the air rises, the smaller the value of the wet adiabatic gradient; with a decrease in the amount of moisture, its value approaches the dry adiabatic gradient.
The vertical temperature gradient at a height of 500 meters should be = 12 є. The vertical temperature gradient at a height of 1000 meters should be = 9 є. The vertical temperature gradient at an altitude of 1500 meters should be = 6 є. But, as soon as the air begins to rise, it will become colder than the surroundings, and with height the temperature difference increases.
But cold air, being heavier, tends to descend, i.e. take the original position. Since the air is unsaturated, when it rises, the temperature should decrease by 1 ° C per 100 m.
Therefore, the temperature of the air mass at a height of 500 meters will be = 10°C. Therefore, the temperature of the air mass at a height of 1000 meters will be = 5°C. Therefore, the temperature of the air mass at an altitude of 1500 meters will be = 0°C.
Determination of the height of the levels of condensation and sublimation
Exercise 1. Determine the height of the level of condensation and sublimation of rising adiabatically air, not saturated with water vapor, if its temperature (T) and water vapor pressure (e) are known; T = 18º, e = 13.6 hPa.
The temperature of the rising air, not saturated with water vapor, changes by 1º every 100 meters. First - according to the curve of dependence of the maximum vapor pressure on the air temperature, it is necessary to find the dew point (φ). Then determine the difference between the air temperature and the dew point (T - f). Multiplying this value by 100 m, find the value of the condensation level. To determine the level of sublimation, you need to find the temperature difference from the dew point to the sublimation temperature and multiply this difference by 200 m.
The level of condensation is the level to which it is necessary to rise in order for the water vapor contained in the air to adiabatically rise to a state of saturation (or 100% relative humidity). The height at which the water vapor in the rising air becomes saturated can be found by the formula: , where T is the air temperature; f - dew point.
f = 2.064 (according to the table)
18 є - 2.064 \u003d 15.936 є x 122 \u003d 1994m water vapor saturation height.
Sublimation occurs at a temperature of -10º.
2.064 - (-10) = 12.064 x 200 = 2413m sublimation level.
Task 2 (B). Air, having a temperature of 12ºC and a relative humidity of 80%, passes over mountains 1500 m high. At what height will the formation of clouds begin? What are the temperatures and relative humidity air at the top of the ridge and behind the ridge?
If the relative air humidity r is known, then the height of the condensation level can be determined by the Ippolitov formula: h=22 (100-r) h = 22 (100-80) = 440m the beginning of the formation of stratus clouds.
The process of cloud formation begins with the fact that a certain mass of sufficiently moist air rises. As you rise, the air will expand. This expansion can be considered adiabatic, since the air rises rapidly, and with a sufficiently large volume, the heat exchange between the considered air and the environment simply does not have time to occur during the rise.
As a gas expands adiabatically, its temperature decreases. So rising up wet air will cool down. When the temperature of the cooling air drops to the dew point, the process of condensation of the vapor contained in the air becomes possible. If there are enough condensation nuclei in the atmosphere, this process begins. If there are few condensation nuclei in the atmosphere, condensation does not begin at a temperature equal to the dew point, but at lower temperatures.
Having reached a height of 440m, the rising moist air will cool down and water vapor will begin to condense. Altitude 440m is the lower boundary of the emerging cloud. The air that continues to flow from below passes through this boundary, and the process of vapor condensation will occur above the specified boundary - the cloud will begin to develop in height. The vertical development of the cloud will stop when the air stops rising; this will form the upper boundary of the cloud.
The temperature at the top of the ridge is +3 ºС and the relative air humidity is 100%.
local time dry adiabatic gradient
Practical material for a geography lesson in grade 6 - UMK: O.A. Klimanov, V.V. Klimanov, E.V. Kim. For consideration, tasks on the topic are proposed "Air temperature".
The solution of geographical problems contributes to the active assimilation of the course of geography, forms general educational and special geographical skills.
Goals:
Development of skills to calculate the air temperature at different heights, calculate the height;
Development of the ability to analyze, draw conclusions.
How does temperature change with height?
When the altitude changes by 1000 meters (1 km), the air temperature changes by 6 ° C (with an increase in altitude, the air temperature decreases, and with a decrease, it rises).
Geographic tasks:
1. At the top of the mountain, the temperature is -5 degrees, the height of the mountain is 4500 m. Determine the temperature at the foot of the mountain?
Solution:
For every kilometer up, the air temperature drops by 6 degrees, that is, if the mountain height is 4500 or 4.5 km, it turns out that:
1) 4.5 x 6 = 27 degrees. This means that the temperature has dropped by 27 degrees, and if it is 5 degrees at the top, then at the foot of the mountain it will be:
2) - 5 + 27 = 22 degrees at the foot of the mountain
Answer: 22 degrees at the foot of the mountain
2. Determine the air temperature at the top of the mountain 3 km, if at the foot of the mountain it was + 12 degrees.
Solution:
If after 1 km the temperature drops by 6 degrees, then
Answer:- 6 degrees at the top of the mountain
3. To what height did the plane rise if the temperature outside it is -30 ° C, and at the surface of the Earth + 12 ° C?
Solution:
2) 42: 6 = 7 km
Answer: the plane rose to a height of 7 km
4. What is the air temperature at the top of the Pamirs, if in July at the foot it is +36°C? The height of the Pamirs is 6 km.
Solution:
Answer: 0 degrees at the top of the mountain
5. Determine the air temperature overboard the aircraft, if the air temperature at the earth's surface is 31 degrees, and the flight altitude is 5 km?
Solution:
Answer: 1 degree outside temperature
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