Dependence of air temperature. Lecture: Thermal belts of the Earth

vost. Then these areas underwent repeated mountain building, which was accompanied by both folding and uplift and subsidence of individual blocks. Folded-block mountains with flat tops and steep slopes in Eurasia include the Ural, Tien Shan, Altai, Sayan, and Transbaikalia ranges. IN North America- this is Appalachia; in Australia - East Australian Mountains.

Volcanic mountains are formed during volcanic eruptions (from lat. Vulcanus- god of fire and blacksmithing among the ancient Romans).These include

Kilimanjaro in Africa, Klyuchevskaya Sopka, Fuji, Etna, Elbrus and Kazbek in Eurasia. (Remember how volcanoes form.)

Mountains and plains are the main elements of the continental relief. Mountains are formed as a result of tectonic uplifts, and plains are formed by the destruction of mountain surfaces or as a result of the accumulation of sedimentary rocks. The plains were formed on stable platforms. Mountains are located mainly in mobile areas.

1. How are plains distinguished by origin?2. How are mountains distinguished by origin?*3. Show plains and mountains on the map and explain their origin (optional).**4. Give examples of the dominant landforms in your area and try to explain their origin.

§ 6. Climate of the Earth. Solar radiation

Main questions. How to distribute

Does solar radiation spread across the earth's surface? What determines the amount of solar radiation?

Solar radiation (from Latin radiatio - radiance) - the entirety of solar radiation. Solar radiation is the most important source of energy for atmospheric processes - the formation of weather and climate, and the main source of life on Earth.

In addition to sunlight, which is perceived by our eyes, invisible ultraviolet and infrared radiation comes from the Sun. In the atmosphere, solar radiation is partially reflected by clouds, partially absorbed, turning into heat, and partially scattered. All radiation arriving at the earth's surface is called total solar radiation. The main part of the radiation reaching the earth's surface is absorbed by arable land (up to 90%) and coniferous forest (up to 80%). Solar radiation,

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which spreads through outer space and reaches the earth's surface, is partially reflected back into the atmosphere. Newly fallen snow and sandy deserts have the greatest reflectivity.

The distribution of solar radiation over the Earth's surface is

nalally. It decreases from the equator to the poles in accordance with the decrease in the angle of incidence sun rays(Fig. 11). However, there are deviations in the zonal distribution of solar radiation. These deviations are explained by different cloudiness and transparency of the atmosphere. Continents

Compared to the oceans, they receive more solar radiation due to less (15-30%) cloud cover above them. In the Northern Hemisphere, where the main part of the Earth is occupied by continents, the total radiation is higher than in the Southern Oceanic Hemisphere.

Thermal zones. Depending on quantity solar heat There are 7 thermal zones on the globe: hot, two moderate, two cold and 2 frost zones. Borders

The markers of thermal zones are isotherms. The hot zone from the north and south is limited by the average annual isothermal

mami +20 °C. Two temperate zones

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sa are limited on the equator side by an average annual isotherm of +20 °C, and on the high latitude side by an isotherm of +10 °C (the average temperature of the warmest months - July in the Northern

And January - in the Southern Hemispheres). The northern border coincides approximately with the forest distribution boundary.

The two cold zones lie between the +10 °C and 0 °C isotherms of the warmest month. On land these are zones

tundra Two frost zones are limited by the 0 °C isotherm of the warmest month. This is the kingdom of eternal snows

and ice.

Temperature distribution over the Earth's surface, just like the sun

radiation, zonally and varies from the equator to the poles. This pattern is clearly displayed on climate maps of the world, which show annual isotherms, isotherms of the warmest and coldest months of the year - July and January. By analyzing annual isotherms on the climate map of the world, the following conclusions can be drawn.

Firstly, in equatorial latitudes, the decrease in air temperature as one moves away from the equator occurs slowly; in moderate latitudes -

quite quickly, in the polar latitudes - again slowly.

Secondly, the temperature at all parallels in the Northern Hemisphere is higher than at similar parallels in the Southern Hemisphere. This phenomenon is explained by the fact that in the Southern Hemisphere a large area is occupied by the ocean, therefore, more heat is expended on evaporation. In addition, the continent of Antarctica, covered with ice, has a significant cooling effect.

Thirdly, isotherms do not coincide with parallels due to unequal conditions of heating and cooling of land and sea, the influence of warm and cold currents in combination with the prevailing westerly winds. This is especially noticeable in the Northern Hemisphere, where most of the land is located.

On the Earth's surface, solar radiation is distributed zonally. Its amount depends on the angle of incidence of the sun's rays on the earth's surface, cloudiness and transparency of the atmosphere. In general, the amount of solar radiation depends on geographic latitude.

1. What is solar radiation?2. Show on a map using isotherms the distribution of temperatures on the Earth's surface. Explain the reasons.*3. Show the boundaries of thermal zones on the climate map of the world.**4. Why are the boundaries of thermal zones drawn using isotherms?

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§ 7. Atmospheric circulation

Main questions. What post-

Are certain winds formed over the earth's surface? What is the relationship between the belts? atmospheric pressure and amount of precipitation?

Atmospheric circulation. I understand-

Studying atmospheric circulation processes will help you understand the processes occurring in the atmosphere, and even to some extent predict weather changes yourself. Atmospheric circulation

atmosphere (from Latin circulation - vor-

flow) is the entire system of air currents over the globe. The pressure difference causes air movement from areas high pressure in the low area.

At equatorial latitudes the pressure is always low. This is explained by the fact that heated from the

At the surface of the Earth, air rises and moves towards tropical latitudes. Therefore, there is increased pressure over the tropics. In temperate latitudes, the pressure is low due to the outflow of warmer air to the polar latitudes. Air coming from temperate latitudes creates increased pressure over the cold surface in the Arctic.

ke and Antarctica. Belts are forming

low (equatorial and temperate) and high pressure (tropical and polar) (Fig. 12).

Distribution of high and low pressure determines the direction of the winds dominant in the troposphere - trade winds, westerly winds of temperate latitudes, northeastern and southeastern winds, monsoons.

Trade winds. At the equator, highly heated air constantly rises, forming updrafts.

Due to this, a

Rice. 12. Pressure belts and prevailing winds

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	§ 7. Atmospheric circulation
	standing equatorial belt low-
	whom pressure. The air rising
	above the equator, in upper layers tro-
	posphere (10-12 km) spreads towards
	poles. Gradually it cools down
	and approximately above 30° north and
	southern latitude (i.e. in the tropics)
	begins to descend. Excess is formed
	air flow, due to which there is
	high pressure belt (Fig. 13).
	Since in the equatorial zone
	low pressure prevails, and in the tro-	Rice. 13. Air movement pattern
	picical - high, then near the surface -	Rice. 13. Air movement pattern
	picical - high, then near the surface -	in equatorial and tropical
	On Earth, the winds blow from high belts
	whom the pressure is towards the equator. Such winds
	called trade winds. Influenced	all areas of high pressure, to
	rotation of the Earth around the axis of the trade winds	zones of low pressure are moderate
	deviate in the Northern Hemisphere	ny latitudes. In these areas it is common
	to the right, i.e. to the west, and blow from the north	northeast winds in the Arctic,
	east to southwest, and in the South -	southeastern - in Antarctica.
	to the left and directed from southeast to	Antarctic southeast winds,
	northwest.	unlike the Arctic north-eastern
	Westerly winds are moderate	accurate, stable and have large
	latitude From tropical zones high	speed.
	whom the pressure winds blow not only to	Monsoons. Their name in translation
	equator, but also towards the poles, so	de means season (from Arabic mausim -
	as in the region of temperate latitudes (65° N.	season). Feature mus-
	and Yu. w.) low pressure prevails.	carotid circulation - change of direction
	However, due to the rotation of the Earth	air movement twice a year
	they gradually deviate to the east	depending on the season. Monsoon in winter
	(in the Northern Hemisphere - to the right, and	blows from land to sea, in summer - from sea
	in Yuzhny - to the left) and create a transformation	to land. In summer, the land quickly warms up
	flowing air flow from the west	the air pressure above it rises and
	to the East . So in temperate latitudes	the top falls. At this time more
	westerly winds are formed.	the cool sea air begins
	In the polar regions of the Earth the wind	move to land. He brings
	ry blow from the poles, where they are located -	not very hot, but rich

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Rice. 14. Formation of monsoons

the air is moist and there is a lot of precipitation. In winter it's the other way around. The continent is cooling much faster than the ocean. An area of low pressure is established over the ocean, and high pressure over the continent, so the winter monsoon blows from land to sea. It carries cold and dry air, partly cloudy dry weather (Fig. 14). The effect of monsoons is strongly manifested in the eastern parts of the continents, where they are adjacent to vast expanses of oceans. (Show on the map the areas of influence of trade winds, westerly winds, monsoons, northeast, southeast winds.)

Distribution of precipitation on Earth.

Atmospheric precipitation on the earth's surface is distributed very unevenly. Some areas suffer from excess moisture, others from lack of it. How can one explain such an uneven distribution of precipitation on the Earth's surface?

The main reason for the uneven

Rice. 15. Distribution of precipitation depending on the latitude of the place

precipitation distribution - placement of belts of low and high atmospheric pressure. (Study the distribution of precipitation over the earth’s surface using the “Annual Precipitation” map.)In the area of the equator and

V In other areas of the earth's surface, where pressure is low, a lot of precipitation falls. In areas of high pressure over the tropics and near the poles, little precipitation falls (Fig. 15).

Distribution of precipitation on Earth

V To a large extent, it also depends on the position of the area relative to the World Ocean, warm or cold currents, and the relief.

Trade winds, westerly winds, northeastern and southeastern winds are constant winds, monsoons are seasonal winds that form above the earth's surface. Belts of high and low atmospheric pressure determine the amount of precipitation on the globe.

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1. What is called atmospheric circulation?2. Which areas of the Earth receive little precipitation and which areas receive a lot? Show them on a map and highlight patterns.*3. Explain the reasons for the constant winds over the earth's surface.**4. What effect does atmospheric circulation have on the climate in your area?

§ 8. Basic types			re. All types of air masses, except
air masses			equatorial, are divided into subtypes:
			maritime and continental depending on
Cyclones and anticyclones
			depending on the nature of the surface, above

Main questions. What determines			which they were formed.
			Equatorial air mass
What are the properties of the air mass? For
			ca is formed in the band of decreased
what latitudes are characterized by the change of cyclones
			pressure. Has high temperatures
and anticyclones?
			temperatures and high humidity.
Air masses are a pain			Continental		tropical
higher volumes of air, which are			air	mass forms over
are settled over a certain ter-			tropical deserts: Sahara,
rhetoric and have relatively			Kalahari and others. It has high
homogeneous properties - temperature			temperature, low humidity.
ratio, humidity, transparency.				tropical	air
They move as one unit in one			the mass forms over the oceans. U
direction in the general system			it has quite high temperatures and
circulation	atmosphere.	Air	high humidity.
mass covers an area of thousands and			Continental		moderate
millions	square	kilometers,	air mass is formed over ma-
extending up several kilos			terikas, dominates in the North
meters. Moving above the surface			lusharia. Its properties vary according to
materials with different properties, they heat-			seasons. Quite high in summer
are cooled or humidified			temperature and humidity, character-
or become drier. There are			we have precipitation. In winter - low and extremely
four zonal types of air masses			low temperatures and low humidity
depending on the areas of formation			ness. Marine temperate air
zones: equatorial, tropical,			the mass is formed over non-freezing
temperate and Arctic (and Antarctic)			mi oceans with warm currents. Le-
tic) air masses. They are from-			then it is cooler, in winter it is warmer,
differ primarily in temperature			characterized by significant humidity.

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Continental Arctic

(Antarctic) air mass is formed over the ice of the Arctic and Antarctica, has extremely low temperatures and low humidity.

tew. Marine Arctic (Antarc-

tic) air mass is formed over periodically freezing seas, its temperature is slightly higher, and its humidity is higher.

Atmospheric front (from Latin frons - forehead, front side) - the border zone between two air masses with different properties. Atmospheric fronts can be warm and cold depending on

depends on what air moves into the territory and what is displaced.

The passage of the front is accompanied by changes in the weather. A warm front moves toward cold air. It is associated with warming, nimbostratus clouds, and precipitation. The cold front moves toward warm air; it brings heavy short-term precipitation and cold temperatures.

Cyclones and anticyclones. In at-

Closed areas of high and low atmospheric pressure are formed in the atmosphere. Cyclone -

this is a closed area with low pressure

lacing in the center. The occurrence of cyclones is associated with atmospheric fronts. In a cyclone air currents directed towards the center. From here they rise in a spiral upward (Fig. 16). Powerful clouds form as a result of rising air currents

Rice. 16. Scheme of air flow in a cyclone

H - low pressure area;

IN - high pressure area

And precipitation falls. In summer, during the passage of cyclones, the temperature decreases, in winter it rises, and a thaw begins. The approach of a cyclone to a certain area causes cloudy weather and a change in wind direction. As the cyclone approaches further, the rain begins to intensify, and the wind consistently changes its direction and also intensifies. The passage of the middle of a cyclone causes

An anticyclone is a closed area with high pressure in the center.

In the center, downward air currents predominate, which spread into different directions near the Earth's surface.

sides (Fig. 17). As the air descends, it loses moisture, becomes drier, and the clouds dissipate. This is why precipitation is not typical for an anticyclone. Both in winter and in summer, they bring cloudless skies and calm winds. During the passage of anticyclones, the weather is sunny, hot in summer, and very cold in winter.

The properties of the air mass are determined by the area of its formation. Air masses, moving from the areas of their formation to other areas with different geographical conditions, gradually change their properties, primarily temperature and humidity, and transform into air masses of a different type. The change of cyclones and anticyclones in temperate latitudes leads to sudden changes in weather.

1. Define the concept of “air mass”. 2. Highlight the differences between a cyclone and an anticyclone.**3. Describe the cyclonic weather you have observed in your area. Is it repeated often?**4. Can we say that hurricanes in North America and typhoons in Southeast Asia are tropical cyclones?

§ 9. Climatic zones of the Earth

Main questions. What is cli-

matic belt? What influence do climatic conditions have on population distribution?

Climatic (from the Greek klimatos - inclination) differences on Earth are directly related to the inclination of the sun's rays to the earth's surface. Climatic zonation manifested in placement climatic zones.Climate zones- This

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territories that encircle the Earth in a continuous or intermittent strip. They differ from each other in temperature, atmospheric pressure, air masses, prevailing winds, amount and regime of precipitation. They stretch from west to east and replace each other from the equator to the poles. Stand out

main and transitional climatic

some belts. In the main climatic zones, one type of air mass dominates throughout the year. In transitional climate zones there are 2 types of air masses. They change with the seasons. The distribution of temperatures and precipitation within the belts is also influenced by other factors: the proximity of oceans, warm and cold currents, and topography. Therefore, large differences are observed within climatic zones and climatic regions with different types of climate are distinguished.

The names of the main climatic zones are given according to the dominant air masses and the latitudes in which they are formed.

Between the main zones there are transitional climatic zones: two subequatorial, two subtropical, subarctic and subantarctic. Their names depend on the dominant types of air masses, and the prefix “sub” (from Latin sub - under) indicates a secondary role in the general circulation system

atmosphere. For example, subequatorial means located next to the equatorial. Air masses in the transition zones change with the seasons: in winter, the air masses of the main belt adjacent to the pole predominate, and in summer, from the equator.

The equatorial belt is formed

was located in the equator region between 5° south. w. and 10° N. w. During the year, equatorial air masses predominate here. Average monthly temperatures range from +25 to +28 °C. Precipitation is 1500-3000 mm per year. This belt is the wettest part of the earth's surface. This is explained by the high position of the Sun above the horizon throughout the year and the rising air currents characteristic of the low pressure belt.

For subequatorial zones

Owls (up to about 20° N and S) are characterized by two seasons: humid equatorial air dominates in summer, and dry tropical air dominates in winter. By summer m is the same as in the equatorial zone, and in winter - as in the tropical zone. The average air temperature in all months ranges from +20 to +30 °C. The annual precipitation on the plains is up to 1000-2000 mm, and on the mountain slopes - up to 6000-10,000 mm. Almost all precipitation falls in summer.

(Remember how trade winds influence climate formation.)

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Thermal zones of the Earth

Uneven heating the earth's surface causes different air temperatures at different latitudes. Latitudinal bands with certain air temperatures are called thermal zones. The belts differ from each other in the amount of heat coming from the Sun. Their extent depending on the temperature distribution is well illustrated by isotherms (From the Greek “iso” - Same, “therma” - Heat). These are lines on a map that connect points with the same temperature.

Hot belt located along the equator, between the Northern and Southern tropics. It is limited on both sides of the 20 0 C isotherms. Interestingly, the boundaries of the belt coincide with the boundaries of the distribution of palm trees on land and corals in the ocean. Here the earth's surface receives the most solar heat. Twice a year (December 22 and June 22) at noon the sun's rays fall almost vertically (at an angle of 90 0). The air from the surface becomes very hot. That's why it's hot there throughout the year.

Temperate zones(In both hemispheres) adjacent to the hot zone. They stretch in both hemispheres between the Arctic Circle and the Tropics. The sun's rays fall on the earth's surface with some inclination. Moreover, the further north, the greater the slope. Therefore, the sun's rays heat the surface less. As a result, the air heats up less. This is why it is colder in temperate zones than in hot zones. The sun is never at its zenith there. Clearly expressed times years: winter, spring, summer, autumn. Moreover, the closer to the Arctic Circle, the longer and colder the winter. The closer to the tropics, the longer and warmer the summer. Temperate zones on the polar side are limited by the warm month isotherm of 10 0 C. It is the limit of forest distribution.

Cold belts The (Northern and Southern) hemispheres lie between the 10 0 C and 0 0 C isotherms of the warmest month. The sun there in winter does not appear above the horizon for several months. And in summer, although it does not go beyond the horizon for months, it stands very low above the horizon. Its rays only glide over the surface of the Earth and heat it weakly. The Earth's surface not only heats, but also cools the air. Therefore, the air temperatures there are low. Winters are cold and harsh, and summers are short and cool.

Two belts of eternal cold(northern and southern) are surrounded by an isotherm with temperatures of all months below 0 0 C. This is the kingdom of eternal ice.

So, the heating and lighting of each area depends on the position in the thermal zone, that is, on the geographic latitude. The closer to the equator, the greater the angle of incidence of the sun's rays, the more the surface heats up and the higher the air temperature. And vice versa, with distance from the equator to the poles, the angle of incidence of the rays decreases, and accordingly the air temperature decreases.

Light belts and their characteristics.

Moderate

Cold

It is located between the tropics and the Arctic Circle within the hemisphere.

The sun is never at its zenith

During the year, the angle of incidence of the sun's rays varies greatly, so thermal seasons of the year are distinguished (summer, autumn, winter, spring). Temperatures in summer and winter are very different. For example, at latitude 50 o

t° summer≈ +20°С

t° winter≈ -10°С

Located between the northern and southern tropics.

The sun is at its zenith twice a year. The surface warms up very well all year round; there is no difference between summer and winter temperatures, there are no thermal seasons of the year, average annual t o =+25 o C. During the year, the duration of daylight hours changes slightly. Approximately day=night=12 hours. There is virtually no twilight.

Located inside the Arctic Circle of each hemisphere.

In winter, the Sun does not rise above the horizon at all - the phenomenon of the Polar Night. In summer, the Sun, on the contrary, does not set beyond the horizon - the phenomenon of the Polar Day. The angle of incidence of sunlight even in summer is very small, so the heating of the surface is very weak. Summer temperatures usually do not exceed +10°C. During the long polar night, strong cooling occurs, because... there is no heat flow at all.

Light belts are parts of the Earth's surface limited by the tropics and polar circles and differing in light conditions.

As a first approximation, it is enough to distinguish three zones in each hemisphere: 1) tropical, limited to the tropics, 2) temperate, extending to the Arctic Circle, and 3) polar. The first is characterized by the presence of the Sun at the zenith at each latitude twice a year (once in the tropics) and a small difference in the length of the day between months. The second is characterized by large seasonal differences in the height of the Sun and the length of the day. The third is characterized by a polar night and a polar day, the longitude of which depends on the geographic latitude. North of the Arctic Circle and south of the Antarctic Circle experience polar day (summer) and polar night (winter). The area from the Arctic Circle to the Pole in both hemispheres is called the Arctic.
Polar day - a period when the Sun is at high latitudes all day long does not fall below the horizon. The length of the polar day increases the further you go to the pole from the Arctic Circle. In the polar circles, the Sun does not set only on the day of the solstice; at 68° latitude, the polar day lasts about 40 days, at the North Pole 189 days, at the South Pole somewhat less, due to the unequal speed of the Earth's orbit in the winter and summer months.
The polar night is a period when the Sun in high latitudes does not rise above the horizon around the clock; a phenomenon opposite to the polar day is observed simultaneously with it at the corresponding latitudes of the other hemisphere. In fact, the polar night is always shorter than the polar day due to the fact that the Sun, when it is not much below the horizon, illuminates the atmosphere and there is no complete darkness (twilight).
However, dividing the Earth into such large belts cannot satisfy practical needs.

On the days of the equinoxes, the height of the midday Sun above the horizon h for different latitudes f is easily determined by the formula: h = 90°-f.
So, in St. Petersburg (ph = 60°) on March 21 and September 23 at noon, the Sun is at an altitude of 90°-60° = 30°. It heats the Earth for 12 hours. In the summer of each hemisphere, when the Sun is above the corresponding tropic, its height at noon increases by 23°27":
A=90°-f+23°27".
For St. Petersburg, for example, on June 21, the altitude of the Sun is: 90°-60°+23°27" = 53°27". The day lasts 18.5 hours.

In winter, when the Sun moves to the opposite hemisphere, its height decreases accordingly and reaches a minimum on the days of the solstices. Then it should be reduced by 23°27".
At the parallel of Leningrad on December 22, the Sun is at an altitude of 90°-60° -23°27" = 6°33" and illuminates the earth's surface for only 5.5 hours.

The described conditions of illumination of the globe, due to the tilt of the earth's axis, represent the radiation, associated with the sun's rays, the basis of the change of seasons.

Not only solar radiation, but also many telluric (terrestrial) factors take part in the formation of the weather, and thus the seasons, so in reality both the seasons and their changes are a complex phenomenon.

The natural change in the position of the Earth relative to the Sun as it moves in orbit while maintaining a certain inclination of the rotation axis determines the position on the Earth of the lines of the tropics and polar circles, limiting the belts of illumination (astronomical thermal belts). They are distinguished depending on the midday height of the Sun and the duration of illumination (the length of the day).
Between the tropics (northern - Tropic of Cancer and southern - Tropic of Capricorn) lies hot astronomical belt, within which the Sun is at its zenith at noon twice a year. At the equator, these moments are separated by equal periods of 6 months (March 21 and September 23). In the tropics, the Sun is at its zenith only once a year - on the days of the solstices (in the northern tropics - June 22, in the southern - December 23). In zones located between the tropics and polar circles, in temperate astronomical zones The sun is not at its zenith, but within 24 hours there is always a change of day and night, and their duration depends on the time of year and latitude. In the polar circles, the Sun does not rise above the horizon higher than 47°, but in the summer it may not hide behind the horizon for a whole day. In winter, the Sun does not appear at all for a whole day. North of the Arctic Circle and south of the Antarctic Circle are cold astronomical belts. They differ in that at a low position above the horizon (less than 47°), the Sun does not hide for up to six months (at the poles) and does not appear for the same period of time (Tables 2, 3).

The higher the Sun is above the horizon, the more solar heat the surface on which its rays fall receives. Therefore, the zones between the tropics are hot, the zones between the polar circles and the poles are cold. Intermediate (located between the tropics and polar circles) zones are moderate in terms of the amount of heat received from the Sun. The lines of the tropics and polar circles can only be taken conditionally as the boundaries of thermal zones, since in reality the temperature is determined by a number of conditions, depending primarily on the nature of the surface. But these lines, of course, are the boundaries of belts with different durations of illumination by the sun's rays.
The location of the line of the tropics and polar circles depends on the angle of inclination of the planet's rotation axis to its orbit. If the Earth's axis did not have an inclination to the orbit, these lines would not exist at all, and the light belts (astronomical thermal belts) would not stand out. This situation exists, for example, on Mercury. On a planet whose axis of rotation is inclined to the orbit by 45°, at a latitude of 45° N. and Yu. in a day summer solstice in the corresponding hemisphere, the sun's rays fall vertically (as in the tropics of the earth), and on the day winter solstice The sun does not appear over the horizon (as in the polar circles on Earth). There will be no temperate astronomical zone on such a planet at all.
A change in the inclination of the planet's rotation axis to its orbit causes expansion or contraction of astronomical thermal belts (light belts).
The result of the rotation of the Earth around its axis and the resulting change of day and night is circadian rhythm processes in the geographical shell of the Earth. During the day, the amount changes naturally solar energy, obtained by the surface, temperature, humidity, atmospheric pressure, and air movement change. Organisms react sensitively to these changes, which in turn influence their environment. The daily rhythm of processes manifests itself against the background of their annual rhythm, determined by the movement of the Earth around its axis, the change of seasons and expressed in the natural change of phenomena in nature.

Heat zones- these are different areas of the globe that receive unequal amounts of heat from the Sun. There are five heat zones on the globe: one hot, two temperate and two cold.

In the hot zone, the sun stands overhead, its rays fall down almost vertically, the length of day and night is approximately the same all year round. In the cold zone, the sun never rises high, its rays almost glide across the surface of the earth, and the winter day is very short. The temperate zone lies between hot and cold. In the temperate summer, the sun shines high in the sky and the days last long. In winter, the days are short, the sun does not rise high and hardly warms the earth.

The region located on both sides of the Equator, between the Northern and Southern tropics, receives the most solar heat. It is hot there all year round and snow never falls on the plains. This territory, stretching from north to south for more than 5 thousand km, is called hot belt.Material from the site

Areas of the globe north of the Arctic Circle and south of the Antarctic Circle receive significantly less solar heat. Here all year round It’s cold, and during the short summer the snow and ice don’t even have time to melt. The sun does not appear at all for several months, and in the summer it is so low that its rays seem to glide across the surface of the Earth (Fig. 129). The area north of the Arctic Circle is called northern cold zone, and south of the Antarctic Circle - southern cold belt.

Stretches between the Arctic Circle and the Tropic of the North northern temperate zone. In the southern hemisphere between the Antarctic Circle and the Tropic of the South is located southern temperate zone.

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1. Thermal zones of the Earth

Uneven heating of the earth's surface causes different air temperatures at different latitudes. Latitudinal bands with certain air temperatures are called thermal zones. The belts differ from each other in the amount of heat coming from the Sun. Their extent depending on the temperature distribution is well illustrated by isotherms (From the Greek “iso” - Same, “therma” - Heat). These are lines on a map that connect points with the same temperature.

The hot zone is located along the equator, between the Northern and Southern tropics. It is limited on both sides of the 20 0C isotherms. Interestingly, the boundaries of the belt coincide with the boundaries of the distribution of palm trees on land and corals in the ocean. Here the earth's surface receives the most solar heat. Twice a year (December 22 and June 22) at noon the sun's rays fall almost vertically (at an angle of 900). The air from the surface becomes very hot. That's why it's hot there throughout the year.

Temperate zones (in both hemispheres) are adjacent to the hot zone. They stretch in both hemispheres between the Arctic Circle and the Tropics. The sun's rays fall on the earth's surface with some inclination. Moreover, the further north, the greater the slope. Therefore, the sun's rays heat the surface less. As a result, the air heats up less. This is why it is colder in temperate zones than in hot zones. The sun is never at its zenith there. Clearly defined seasons: winter, spring, summer, autumn. Moreover, the closer to the Arctic Circle, the longer and colder the winter. The closer to the tropics, the longer and warmer the summer. Temperate zones on the polar side are limited by the warm month isotherm of 10 0C. It is the limit of forest distribution.

The cold belts (Northern and Southern) of both hemispheres lie between the isotherms of 10 0C and 0 0C of the warmest month. The sun there in winter does not appear above the horizon for several months. And in summer, although it does not go beyond the horizon for months, it stands very low above the horizon. Its rays only glide over the surface of the Earth and heat it weakly. The Earth's surface not only heats, but also cools the air. Therefore, the air temperatures there are low. Winters are cold and harsh, and summers are short and cool.

Two zones of eternal cold (northern and southern) are surrounded by an isotherm with temperatures of all months below 0 0C. This is the kingdom of eternal ice.

It is important to remember that the lines of the tropics and polar circles outside the thermal zones are taken conditionally. Since in reality the air temperature is also determined by a number of other conditions (see the article main and transitional climate zones).

1.1 Roast

The equatorial belt is a zone of low pressure, rising air currents, and weak winds. Temperatures are high all year round (about +28 °C), air humidity is high. There is a lot of precipitation - about 2000 mm. Seasonal fluctuations in average monthly temperatures and precipitation are insignificant.

Subequatorial belts are characterized by seasonal changes in air masses: the summer monsoon brings hot and humid equatorial air, while dry continental tropical air dominates in winter. This type of climate with wet summers and dry winters is called monsoon climate.

Tropical zones are characterized by an arid (dry) climate, they contain the greatest deserts in the world: the Sahara, Arabian, and Australian. The air temperature ranges from +20 °C in summer to +15 °C in winter.

1.2 Moderate

In subtropical zones, air masses change from tropical in summer to moderate in winter, and temperatures are above zero throughout the year. However, short-term drops in temperature to negative values and even snowfall are possible. On the plains the snow melts quickly, but in the mountains it can remain for several months. In inland areas the climate is arid, with hot (about +30 °C) dry summers, cool (0...+5 °C), relatively wet (200-250 mm) winters. Changes in air masses and frequent passage of atmospheric fronts determine unstable weather. Due to insufficient moisture, landscapes of deserts, semi-deserts, and dry steppes predominate here. A special sharply continental climate with cool summers, harsh winter and insignificant precipitation, the largest and highest (4-5 km) highland of the world, Tibet, with high-mountain deserts stands out.

In the Southern Hemisphere, where there are no large continents, and only a narrow part enters the temperate zone South America, island of Tasmania and South New Zealand, mild oceanic climate with warm winter and cool summers, uniformly heavy (about 1000 mm) precipitation. And only in Patagonia the climate is transitional to continental, and the moisture is insufficient.

In the Northern Hemisphere, on the contrary, vast land masses dominate and a whole spectrum of climates differing in the degree of continentality is developed. From west to east - from moderate to sharply continental climate - daily and seasonal temperature amplitudes increase, and annual quantity precipitation decreases from 700-600 mm to 300 mm and even to 200-100 mm in Central and Central Asia. In summer there is more precipitation than in winter, and this difference is more significant in the center of the continents, especially in Eastern Siberia, due to the very dry anticyclonic winter.

In the temperate zone, there is a northern part with cool summers and relatively harsh winters and a southern part with warm summers and relatively harsh winters. mild winter.. July temperatures vary from -4...-10 °c to +12 °c in the north and up to +30 °c in the south, January temperatures from -5 °c in the west to -25...-30 °c in in the center of the continents, in Yakutia even below -40 °C.

1.2 Cold

The subarctic and subantarctic belts are characterized by seasonal changes in air masses: in the summer it is PV, in the winter it is AB. In the north of Eurasia and North America, the climate is continental and sharply continental with cool, damp summers with temperatures less than +10...+12 °C and long, harsh (up to -40...-50 °C) winters with little snow and large annual temperature amplitudes . In the area of Oymyakon there is the pole of cold of the Northern Hemisphere and the entire planet - (-78 °c). Such conditions help maintain widespread permafrost. There is little precipitation (200-100 mm), but due to low temperatures there is excess moisture. The tundra and forest-tundra that dominate here are very swampy.

The marine climate of the northern and southern coasts is characterized by cool (+3...+5 °c) damp summers, relatively mild (-10...-15 °c) winters, floating sea and continental ice, constant fogs with significant amounts of precipitation for such low temperatures (up to 500 mm). Tundra is widespread along the coasts of continents and islands.

In the Arctic (Greenland and the islands of the Canadian archipelago) and Antarctic zones (Antarctica), the continental climate predominates. These are the coldest regions of the Earth - the thermometer does not rise above zero all year, and at the inland Antarctic Vostok station an absolute minimum temperature of -89.2 °C was recorded (but the Vostok station is located at an altitude of 3488 m). Precipitation is less than 100 mm. Here you can hardly see anything other than icy deserts. The Arctic has an oceanic climate. Negative temperatures prevail, but during the polar day it can warm up to +5 °C. There is also little precipitation; the islands are characterized by tundra.

2. Air masses

Large masses of air in the troposphere, comparable in size to a continent or ocean and having more or less the same properties (temperature, humidity, transparency, dust content, etc. - note from geoglobus.ru), are called air masses. They extend upward for several kilometers, reaching the boundaries of the troposphere.

Air masses move from one region of the globe to another, determining the climate and weather in a given area. Each air mass has properties characteristic of the area over which it formed.

Moving to other territories, it carries with it its own weather regime. But passing over a territory with different properties, air masses gradually change, transform, acquiring new qualities.

Depending on the regions of formation, four types of air masses are distinguished: Arctic (in the Southern Hemisphere - Antarctic), temperate, tropical and equatorial. All types are divided into subtypes that have their own characteristic properties. Continental air masses form over continents, and oceanic air masses form over oceans. Shifting along with the atmospheric pressure belts throughout the year, air masses occupy not only the permanent zones of their residence, but seasonally dominate in neighboring, transitional climate zones. In the process of general atmospheric circulation, air masses of all types are interconnected.

Air masses that move from a colder earth's surface to a warmer one and that have a lower temperature than the surrounding air are called cold air masses. They bring cooling, but they themselves warm up from below from the warm earth's surface, while powerful cumulus clouds form and heavy rains fall. Particularly severe cold snaps occur in temperate latitudes with the invasion of cold masses from the Arctic and Antarctica - approx. from geoglobus.ru. Cold air masses sometimes reach southern Europe and even North Africa, but are most often delayed by the Alpine mountain ranges. In Asia, Arctic air freely spreads over vast territories, up to the mountain ranges of southern Siberia. In North America, mountain ranges are located meridianally, so cold arctic air masses penetrate as far as the Gulf of Mexico.

Air masses that have a higher temperature than the surrounding air and arrive at the colder earth's surface are called warm air masses. They bring warming, and they themselves cool from below, and stratus clouds and fogs form. In summer, warm tropical air masses from North Africa sometimes penetrate to the northern regions of Europe and significantly increase the temperature (sometimes up to +30 °C).

Local, or neutral, air mass is a mass that is in thermal equilibrium with its environment, that is, maintaining its properties day after day. A changing air mass can be either warm or cold, and once the transformation is complete, it becomes local.

Where air masses meet different types, atmospheric fronts form.

Moderate air masses form in temperate latitudes. Those that form over the continent are characterized by low temperatures and low content moisture and bring clear and frosty weather. In summer, continental temperate air masses are dry and hot. Temperate air masses formed over the ocean are warm and humid. In winter they bring thaws, and in summer they bring cold temperatures and precipitation.

Arctic and Antarctic air masses form over the icy surface of the polar latitudes. They are characterized by low temperature and a small amount of moisture. They significantly lower the temperature of the areas they invade. In the summer, moving towards the center of Eurasia, these air masses gradually warm up, dry out even more and become the cause of dry winds in the southern regions of the West Siberian Lowland.

Tropical air masses are hot at any time of the year. The marine subtype of tropical air masses is characterized by high humidity, while the continental subtype is dry and dusty. The trade winds dominate the oceans in the tropics all year round - approx. from geoglobus.ru. The air masses that form in these areas are characterized by moderately high temperatures from +20 to +27 °C in summer and cool temperatures up to +10 +15 °C in winter. In areas of tropical deserts over the continents, extremely dry air masses with average temperatures of +26 +40 ° C are formed.

Equatorial air masses are formed at equatorial latitudes. They have high temperature and high humidity, regardless of where they formed - over the continent or over the ocean. The average temperatures of equatorial air masses in all months of the year range from +24 to +28 °C. Since evaporation in these areas is high, so is the absolute humidity, and the relative humidity even in the driest months of the year is above 70%.

3. Atmospheric precipitation

thermal zone air atmospheric

Their education

Atmospheric precipitation is any moisture that falls from the atmosphere onto the earth's surface. These include rain, snow, hail, dew, and frost. Precipitation can fall both from clouds (rain, snow, hail) and from the air (dew, frost).

The main condition of education atmospheric precipitation is cooling warm air, leading to condensation of the steam contained in it.

As warm air rises and cools, clouds consisting of water droplets form. Colliding in the cloud, the drops connect and their mass increases. The bottom of the cloud turns blue and it starts to rain. At negative temperatures air, water droplets in the clouds freeze and turn into snowflakes. Snowflakes stick together into flakes and fall to the ground. During snowfall, they may melt a little, and then wet snow falls. It happens that air currents repeatedly lower and raise frozen drops, at which time ice layers grow on them. Finally the drops become so heavy that they fall to the ground like hail. Sometimes hailstones reach the size of a chicken egg.

IN summer time When the weather is clear, the earth's surface cools. It cools the ground layers of air. Water vapor begins to condense on cold objects - leaves, grass, stones. This is how dew is formed. If the surface temperature was negative, then the water droplets freeze, forming frost. Dew usually falls in summer, frost - in spring and autumn. At the same time, both dew and frost can form only in clear weather. If the sky is covered with clouds, then the earth's surface cools slightly and cannot cool the air.

According to the method of formation, convective, frontal and orographic precipitation are distinguished. General condition The formation of precipitation is the upward movement of air and its cooling. In the first case, the reason for the rise of air is its heating from a warm surface (convection). Such precipitation falls all year round in the hot zone and in the summer in temperate latitudes. If warm air rises when interacting with colder air, frontal precipitation forms. They are more characteristic of temperate and cold zones, where warm and cold air masses are more common. The reason for the rise of warm air may be its collision with mountains. In this case, orographic precipitation is formed. They are typical for the windward slopes of mountains, and the amount of precipitation on the slopes is greater than in the adjacent areas of the plains.

The amount of precipitation is measured in millimeters. On average, about 1100 mm of precipitation falls on the earth's surface per year.

Distribution of precipitation on the globe. Atmospheric precipitation on the planet is distributed unevenly. This depends on the geographic location of the area and prevailing winds. The greatest amount of precipitation falls in equatorial (over 2,000 mm) and temperate (over 800 mm) latitudes. Little precipitation (200 mm) falls in tropical and polar latitudes. However, this distribution is disrupted by the nature of the earth's surface: more precipitation falls over the oceans than over land. In the mountains, much more precipitation is “accepted” by those slopes facing the prevailing winds. Thus, in Ukraine, the windward slopes of the Carpathians receive 1500 mm per year, and the leeward ones - half as much -750 mm per year.

The record highest annual rainfall on Earth is in the village of Cherrapunji, at the foot of the Himalayas - 23,000 mm. And the wettest place on the planet is considered to be the Hawaiian Islands, where it rains 335 days a year, bringing 12,000 mm of water. Record-breaking dry places where precipitation has not fallen for years are the Atacama desert in South America (1 mm per year) and the Sahara desert in Africa (5 mm per year).

The distribution of precipitation on Earth depends on a number of reasons:

a) from the placement of high and low pressure belts. At the equator and in temperate latitudes, where low pressure areas form, there is a lot of precipitation. In these areas, the air heated by the Earth becomes light and rises, where it meets the cooler layers of the atmosphere, cools, and the water vapor turns into water droplets and falls to the Earth as precipitation. In the tropics (30th latitude) and polar latitudes, where areas of high pressure form, downward air currents predominate. Cold air descending from the upper troposphere contains little moisture. When lowered, it contracts, heats up and becomes even drier. Therefore, in areas of high pressure over the tropics and at the poles, little precipitation falls;

b) the distribution of precipitation also depends on geographic latitude. At the equator and in temperate latitudes there is a lot of precipitation. However, the earth's surface at the equator warms up more than in temperate latitudes, therefore the updrafts at the equator are much more powerful than in temperate latitudes, and therefore, precipitation is stronger and more abundant;

c) the distribution of precipitation depends on the position of the area relative to the World Ocean, since it is from there that the main share of water vapor comes. For example, in Eastern Siberia there is less precipitation than on the East European Plain, since Eastern Siberia far from the oceans;

d) the distribution of precipitation depends on the proximity of the area to ocean currents: warm currents contribute to precipitation on the coasts, while cold currents prevent it. Cold currents pass along the western coasts of South America, Africa and Australia, which led to the formation of deserts on the coasts; e) the distribution of precipitation also depends on the topography. On the slopes of mountain ranges facing moist winds from the ocean, much more moisture falls than on the opposite slopes - this is clearly visible in the Cordillera of America, on the eastern slopes of the mountains Far East, on the southern spurs of the Himalayas. Mountains prevent the movement of moist air masses, and the plain facilitates this.

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