Atmosphere— air envelope, surrounding the globe, connected to it by gravity and taking part in its daily and annual rotation.

Atmospheric air consists of a mechanical mixture of gases, water vapor and impurities. The composition of the air up to an altitude of 100 km is 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.03% carbon dioxide, and only 0.01% is the share of all other gases: hydrogen, helium, water vapor, ozone. The gases that make up air mix all the time. The percentage of gases is fairly constant. However, the carbon dioxide content varies. Burning oil, gas, coal, and reducing the number of forests leads to an increase in carbon dioxide in the atmosphere. This contributes to the rise in air temperature on Earth, as carbon dioxide allows solar energy to reach the Earth and blocks the Earth's thermal radiation. Thus, carbon dioxide is a kind of “insulation” of the Earth.

There is little ozone in the atmosphere. At an altitude of 25 - 35 km, a concentration of this gas is observed, the so-called ozone screen (ozone layer). The ozone screen performs the most important protective function - it blocks ultraviolet radiation from the Sun, which is harmful to all life on Earth.

Atmospheric water is in the air in the form of water vapor or suspended condensation products (droplets, ice crystals).

Atmospheric impurities(aerosols) - liquid and solid particles found mainly in the lower layers of the atmosphere: dust, volcanic ash, soot, ice crystals and sea ​​salt etc. The amount of atmospheric impurities in the air increases during severe forest fires, dust storms, and volcanic eruptions. The underlying surface also affects the quantity and quality of atmospheric pollutants in the air. So, over deserts there is a lot of dust, over cities there are a lot of small solid particles and soot.

The presence of impurities in the air is associated with the content of water vapor in it, since dust, ice crystals and other particles serve as nuclei around which water vapor condenses. Like carbon dioxide, atmospheric water vapor serves as an “insulation” for the Earth: it delays radiation from the earth’s surface.

The mass of the atmosphere is one millionth of the mass of the globe.

The structure of the atmosphere. The atmosphere has a layered structure. The layers of the atmosphere are distinguished based on changes in air temperature with height and other physical properties (Table 1).

Table 1.The structure of the atmosphere

Atmosphere Sphere	Height of the bottom and top borders	Temperature change depending on altitude
Troposphere		Demotion
Stratosphere	8-18 — 40-50 km	Promotion
Mesosphere	40-50 km – 80 km	Demotion
Thermosphere		Promotion
Exosphere	Above 800 km (it is conventionally believed that the atmosphere extends to an altitude of 3000 km)

Troposphere— the lower layer of the atmosphere containing 80% air and almost all water vapor. The thickness of the troposphere is not the same. At tropical latitudes - 16-18 km, in temperate latitudes - 10-12 km, and in polar latitudes - 8-10 km. Everywhere in the troposphere the air temperature drops by 0.6 ° C for every 100 m of ascent (or 6 ° C per 1 km). The troposphere is characterized by vertical (convection) and horizontal (wind) air movements. All types of air masses are formed in the troposphere, cyclones and anticyclones arise, clouds, precipitation, and fogs are formed. Weather is formed mainly in the troposphere. Therefore, the study of the troposphere is of particular importance. The lower layer of the troposphere, called ground layer, characterized by high dust content and content of volatile microorganisms.

The transition layer from the troposphere to the stratosphere is called tropopause. The rarefaction of the air in it sharply increases, its temperature drops to -60 ° From above the poles to -80 ° From above the tropics. The lower air temperature over the tropics is explained by powerful upward air currents and a higher position of the troposphere.

Stratosphere- layer of the atmosphere between the troposphere and mesosphere. The gas composition of the air is similar to the troposphere, but contains much less water vapor and more ozone. At an altitude of 25 to 35 km, the highest concentration of this gas is observed (ozone shield). Up to an altitude of 25 km, the temperature changes little with height, and above it begins to increase. Temperatures vary depending on latitude and time of year. Pearlescent clouds are observed in the stratosphere; it is characterized by high wind speeds and jet air currents.

For upper layers the atmosphere is characterized by auroras and magnetic storms. Exosphere- the outer sphere from which light atmospheric gases (for example, hydrogen, helium) can flow into outer space. The atmosphere does not have a sharp upper boundary and gradually passes into outer space.

The presence of an atmosphere is of great importance for the Earth. It prevents excessive heating of the earth's surface during the day and cooling at night; protects the Earth from ultraviolet radiation from the Sun. A significant part of meteorites burns up in dense layers of the atmosphere.

Interacting with all the shells of the Earth, the atmosphere participates in the redistribution of moisture and heat on the planet. It is a condition for the existence of organic life.

Solar radiation and air temperature. The air is heated and cooled by the earth's surface, which in turn is heated by the Sun. The totality of solar radiation is called solar radiation. The main part of solar radiation is dissipated in space; only one two-billionth part of solar radiation reaches the Earth. Radiation can be direct or diffuse. Solar radiation that reaches the Earth's surface in the form of direct sunlight emanating from the solar disk on a clear day is called direct radiation. Solar radiation that has undergone scattering in the atmosphere and reaches the Earth's surface from the entire vault of heaven is called scattered radiation. Scattered solar radiation plays a significant role in energy balance Earth, appearing in cloudy weather, especially in high latitudes, the only source of energy in the surface layers of the atmosphere. The totality of direct and scattered radiation arriving on a horizontal surface is called total radiation.

The amount of radiation depends on the duration of illumination of the surface by the sun's rays and the angle of their incidence. The smaller the angle of incidence of the sun's rays, the less solar radiation the surface receives and, therefore, the less the air above it heats up.

Thus, the amount of solar radiation decreases when moving from the equator to the poles, since this reduces the angle of incidence of solar rays and the duration of illumination of the territory in winter.

The amount of solar radiation is also affected by cloudiness and transparency of the atmosphere.

The greatest total radiation exists in tropical deserts. At the poles on the day of the solstices (at the North - June 22, at the South - December 22), when the Sun is not setting, the total solar radiation is greater than at the equator. But due to the fact that the white surface of snow and ice reflects up to 90% of the sun's rays, the amount of heat is insignificant, and the surface of the earth does not heat up.

The total solar radiation reaching the Earth's surface is partially reflected by it. Radiation reflected from the surface of the earth, water or clouds on which it falls is called reflected. But still, most of the radiation is absorbed by the earth's surface and turns into heat.

Since the air is heated from the surface of the earth, its temperature depends not only on the factors listed above, but also on the height above ocean level: the higher the area is located, the lower the temperature (decreases by 6 ° With every kilometer in the troposphere).

Affects the temperature and distribution of land and water, which are heated differently. Land heats up quickly and cools down quickly, water heats up slowly but retains heat longer. Thus, the air over land is warmer during the day than over water, and colder at night. This influence is reflected not only in daily, but also in seasonal patterns of air temperature changes. Thus, in coastal areas, under other identical conditions, summers are cooler and winters are warmer.

Due to the heating and cooling of the Earth's surface day and night, during the warm and cold seasons, the air temperature changes throughout the day and year. The highest temperatures of the ground layer are observed in desert areas of the Earth - in Libya near the city of Tripoli +58 ° C, in Death Valley (USA), in Termez (Turkmenistan) - up to +55 ° C. The lowest are in the interior of Antarctica - down to -89 °C. In 1983, -83.6 was recorded at the Vostok station in Antarctica ° C is the minimum air temperature on the planet.

Air temperature- a widely used and well-studied weather characteristic. The air temperature is measured 3-8 times a day, determining the average daily; The daily average is used to determine the monthly average, and the monthly average is used to determine the annual average. Temperature distributions are shown on maps isotherms. Temperature indicators for July, January and annual temperatures are usually used.

Atmosphere pressure. Air, like any body, has mass: 1 liter of air at sea level has a mass of about 1.3 g. For every square centimeter of the earth's surface, the atmosphere presses with a force of 1 kg. This is the average air pressure above ocean level at latitude 45° at a temperature of 0 ° C corresponds to the weight of a mercury column with a height of 760 mm and a cross-section of 1 cm 2 (or 1013 mb.). This pressure is taken as normal pressure. Atmosphere pressure - the force with which the atmosphere presses on all objects in it and on the earth's surface. Pressure is determined at each point in the atmosphere by the mass of the overlying column of air with a base equal to unity. With increasing altitude Atmosphere pressure decreases, because the higher the point is located, the lower the height of the air column above it. As the air rises, it becomes thinner and its pressure decreases. IN high mountains the pressure is significantly less than at sea level. This pattern is used to determine the absolute height of the area based on pressure.

Pressure stage- vertical distance at which atmospheric pressure decreases by 1 mmHg. Art. In the lower layers of the troposphere, up to a height of 1 km, the pressure decreases by 1 mm Hg. Art. for every 10 m of height. The higher it is, the slower the pressure drops.

In the horizontal direction near the earth's surface, pressure changes unevenly, depending on time.

Pressure gradient- an indicator characterizing the change in atmospheric pressure above the earth's surface per unit distance and horizontally.

The amount of pressure, in addition to the altitude of the area above sea level, depends on the air temperature. The pressure of warm air is less than that of cold air, because when heated, it expands, and when cooled, it contracts. As the air temperature changes, its pressure changes. Since the change in air temperature on the globe is zonal, zonality is also characteristic of the distribution of atmospheric pressure on the earth's surface. A belt stretches along the equator low blood pressure, at 30-40° latitudes to the north and south there are belts of high pressure, at 60-70° latitudes the pressure is again reduced, and in the polar latitudes there are areas of high pressure. The distribution of belts of high and low pressure is associated with the characteristics of heating and air movement near the Earth's surface. In equatorial latitudes, the air heats up well throughout the year, rises and spreads towards tropical latitudes. Approaching 30-40° latitudes, the air cools and falls down, creating a belt of high pressure. In polar latitudes, cold air creates areas of high pressure. Cold air constantly sinks down, and air from temperate latitudes comes in its place. The outflow of air to the polar latitudes is the reason why a belt of low pressure is created in temperate latitudes.

Pressure belts exist constantly. They only shift slightly to the north or south depending on the time of year (“following the Sun”). The exception is the low pressure belt of the Northern Hemisphere. It exists only in summer. Moreover, a huge area of ​​low pressure is formed over Asia with a center in tropical latitudes - the Asian low. Its formation is explained by the fact that the air over a huge landmass warms up greatly. In winter, the land, which occupies significant areas in these latitudes, cools greatly, the pressure above it increases, and areas of high pressure are formed over the continents - the Asian (Siberian) and North American (Canadian) winter maximums of atmospheric pressure. Thus, in winter, the low pressure belt in the temperate latitudes of the Northern Hemisphere “breaks”. It persists only over the oceans in the form of closed areas of low pressure - the Aleutian and Icelandic lows.

The influence of the distribution of land and water on the patterns of changes in atmospheric pressure is also expressed in the fact that throughout the year baric maxima exist only over the oceans: Azores (North Atlantic), North Pacific, South Atlantic, South Pacific, South Indian.

Atmospheric pressure is constantly changing. main reason changes in pressure - changes in air temperature.

Atmospheric pressure is measured using barometers. An aneroid barometer consists of a hermetically sealed thin-walled box, inside of which the air is rarefied. When the pressure changes, the walls of the box are pressed in or out. These changes are transmitted to a pointer, which moves along a scale graduated in millibars or millimeters.

Maps show the distribution of pressure across the Earth isobars. Most often, maps indicate the distribution of isobars in January and July.

The distribution of areas and belts of atmospheric pressure significantly influences air currents, weather and climate.

Wind- horizontal movement of air relative to the earth's surface. It arises as a result of uneven distribution of atmospheric pressure and its movement is directed from areas with higher pressure to areas where the pressure is lower. Due to the continuous change in pressure in time and space, the speed and direction of the wind are constantly changing. The direction of the wind is determined by the part of the horizon from which it blows (the north wind blows from north to south). Wind speed is measured in meters per second. With height, the direction and strength of the wind change due to a decrease in the friction force, as well as due to changes in pressure gradients.

So, the cause of wind is the difference in pressure between different areas, and the cause of the difference in pressure is the difference in heating. The winds are affected by the deflecting force of the Earth's rotation.

Winds are varied in origin, character, and meaning. The main winds are breezes, monsoons, and trade winds.

Breeze— local wind (sea coasts, large lakes, reservoirs and rivers), which changes its direction twice a day: during the day it blows from the side of the reservoir to the land, and at night - from the land to the reservoir. Breezes arise because during the day the land heats up more than the water, causing the warmer and lighter air above the land to rise and be replaced by colder air from the side of the reservoir. At night, the air above the reservoir is warmer (because it cools more slowly), so it rises, and in its place masses of air from the land move - heavier, cooler (Fig. 12). Other types of local winds are foehn, bora, etc.

Rice. 12

Trade winds— constant winds in the tropical regions of the Northern and Southern Hemispheres, blowing from high pressure zones (25-35° N and S) to the equator (into the low pressure belt). Under the influence of the Earth's rotation around its axis, the trade winds deviate from their original direction. In the Northern Hemisphere they blow from northeast to southwest, in the Southern Hemisphere they blow from southeast to northwest. Trade winds are characterized by great stability of direction and speed. Trade winds have a great influence on the climate of the areas under their influence. This is especially reflected in the distribution of precipitation.

Monsoons— winds that, depending on the seasons of the year, change direction to the opposite or close to it. In the cold season they blow from the mainland to the ocean, and in the warm season - from the ocean to the mainland.

Monsoons are formed due to differences in air pressure resulting from uneven heating of land and sea. In winter, the air over land is colder, over the ocean it is warmer. Consequently, the pressure is higher over the continent, lower over the ocean. Therefore, in winter, air moves from the mainland (an area of ​​higher pressure) to the ocean (over which the pressure is lower). In the warm season, it’s the other way around: the monsoons blow from the ocean to the mainland. Therefore, in monsoon areas, precipitation usually occurs in summer. Due to the rotation of the Earth around its axis, the monsoons deviate to the right in the Northern Hemisphere, and to the left in the Southern Hemisphere from their original direction.

Monsoons are an important part of the general circulation of the atmosphere. Distinguish extratropical And tropical(equatorial) monsoons. In Russia, extratropical monsoons operate on the Far Eastern coast. Tropical monsoons are more pronounced and are most characteristic of South and Southeast Asia, where individual years During the wet season, several thousand millimeters of precipitation falls. Their formation is explained by the fact that equatorial belt low pressure moves slightly to the north or south depending on the time of year (“following the Sun”). In July it is located at 15 - 20° N. w. Therefore, the southeast trade wind of the Southern Hemisphere, rushing towards this low pressure belt, crosses the equator. Under the influence of the deflecting force of the Earth's rotation (around its axis) in the Northern Hemisphere, it changes its direction and becomes southwestern. This is the summer equatorial monsoon, which carries sea air masses equatorial air to a latitude of 20-28°. Meeting the Himalayas on your way, wet air leaves on their southern slopes significant amount precipitation. At Cherrapunja station in Northern India, the average annual rainfall exceeds 10,000 mm per year, and in some years even more.

From high pressure belts, winds blow towards the poles, but when they deviate to the east, they change their direction to the west. Therefore, in temperate latitudes they predominate western winds, although they are not as constant as the trade winds.

The predominant winds in the polar regions are northeasterly winds in the Northern Hemisphere and southeasterly winds in the Southern Hemisphere.

Cyclones and anticyclones. Due to the uneven heating of the earth's surface and the deflecting force of the earth's rotation, huge (up to several thousand kilometers in diameter) atmospheric vortices are formed - cyclones and anticyclones (Fig. 13).

Rice. 13. Air movement pattern

Cyclone - an ascending vortex in the atmosphere with a closed region of low pressure, in which winds blow from the periphery to the center (counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere). average speed The cyclone moves 35 - 50 km/h, and sometimes up to 100 km/h. In a cyclone, air rises, which affects the weather. With the emergence of a cyclone, the weather changes quite dramatically: winds become stronger, water vapor quickly condenses, generating heavy cloudiness, and precipitation falls.

Anticyclone- descending atmospheric vortex with a closed area of ​​high pressure, in which winds blow from the center to the periphery (in the Northern Hemisphere - clockwise, in the Southern Hemisphere - counterclockwise). In an anticyclone, the air sinks down, becoming drier as it warms up, since the vapors contained in it move away from saturation. This, as a rule, excludes the formation of clouds in the central part of the anticyclone. Therefore, during an anticyclone the weather is clear, sunny, without precipitation. In winter it is frosty, in summer it is hot.

Water vapor in the atmosphere. There is always a certain amount of moisture in the atmosphere in the form of water vapor that has evaporated from the surface of oceans, lakes, rivers, soil, etc. Evaporation depends on air temperature and wind (even a weak wind increases evaporation three times, because all the time carries away air saturated with water vapor and brings new portions of dry air), the nature of the relief, vegetation cover, and soil color.

Distinguish volatility - the amount of water that could evaporate under given conditions per unit time, and evaporation - the actual amount of water that has evaporated.

In the desert, evaporation is high and evaporation is insignificant.

Air saturation. At each specific temperature, the air can accept water vapor up to a certain limit (until saturation).

The higher the temperature, the more maximum amount water may contain air. If you cool unsaturated air, it will gradually approach the saturation point. The temperature at which a given unsaturated air becomes saturated is called dew point. If saturated air is cooled further, excess water vapor will begin to thicken in it. Moisture will begin to condense, clouds will form, and then precipitation will fall.

Therefore, to characterize the weather it is necessary to know relative air humidity - the percentage ratio of the amount of water vapor contained in the air to the amount it can contain when saturated. Absolute humidity — amount of water vapor in grams , located in this moment in 1 m 3 of air.

Atmospheric precipitation and its formation.Precipitation- water in a liquid or solid state that falls from the clouds. Clouds are called accumulations of water vapor condensation products suspended in the atmosphere - water droplets or ice crystals. Depending on the combination of temperature and degree of moisture, droplets or crystals are formed different shapes and magnitude. Small droplets float in the air, larger ones begin to fall in the form of drizzle (drizzle) or light rain. At low temperatures, snowflakes form.

The pattern of precipitation formation is as follows: the air cools (more often when rising upward), approaches saturation, water vapor condenses, and precipitation forms.

The amount of precipitation is measured using a rain gauge - a cylindrical metal bucket with a height of 40 cm and a cross-sectional area of ​​500 cm 2. All quantity measurements atmospheric precipitation are summed up for each month, and the average monthly and then annual precipitation is displayed.

The amount of precipitation in an area depends on:

• air temperature (affects evaporation and air moisture capacity);
• sea ​​currents (above the surface of warm currents, the air is heated and saturated with moisture; when it is transported to neighboring, colder areas, precipitation is easily released from it. Above cold currents, the opposite process occurs: evaporation above them is small; when air poorly saturated with moisture enters the warmer underlying surface, it expands, its saturation with moisture decreases, and precipitation does not form in it);
• atmospheric circulation (where air moves from sea to land, there is more precipitation);
• the height of the place and the direction of mountain ranges (mountains force air masses saturated with moisture to rise upward, where, due to cooling, condensation of water vapor and the formation of precipitation occurs; there is more precipitation on the windward slopes of mountains).

Precipitation is uneven. It obeys the law of zonality, that is, it changes from the equator to the poles. In tropical and temperate latitudes, the amount of precipitation changes significantly when moving from the coasts to the interior of the continents, which depends on many factors (atmospheric circulation, the presence of ocean currents, relief, etc.).

Precipitation on larger territory the globe occurs unevenly throughout the year. Near the equator, the amount of precipitation changes slightly throughout the year; in subequatorial latitudes, there is a dry season (up to 8 months), associated with the action of tropical air masses, and a rainy season (up to 4 months), associated with the arrival of equatorial air masses. When moving from the equator to the tropics, the duration of the dry season increases, and the rainy season decreases. In subtropical latitudes, winter precipitation predominates (it is brought by moderate air masses). In temperate latitudes, precipitation falls throughout the year, but in the interior of the continents, more precipitation falls in the warm season. In polar latitudes, summer precipitation also predominates.

Weather- the physical state of the lower layer of the atmosphere in a certain area at a given moment or for a certain period of time.

Weather characteristics - air temperature and humidity, atmospheric pressure, cloudiness and precipitation, wind. Weather is an extremely variable element natural conditions, subject to daily and annual rhythms. The circadian rhythm is determined by the heating of the earth's surface by the sun's rays during the day and cooling at night. The annual rhythm is determined by the change in the angle of incidence of the sun's rays throughout the year.

Weather matters a lot in economic activity person. Weather studies are carried out on weather stations using a variety of devices. Based on information received at weather stations, synoptic maps are compiled. Synoptic map- a weather map on which atmospheric fronts and weather data at a certain moment are marked with symbols (air pressure, temperature, wind direction and speed, cloudiness, position of warm and cold fronts, cyclones and anticyclones, precipitation patterns). Synoptic maps are compiled several times a day; comparing them allows us to determine the paths of movement of cyclones, anticyclones, atmospheric fronts.

Atmospheric front— zone of separation of air masses of different properties in the troposphere. Occurs when masses of cold and warm air approach and meet. Its width reaches several tens of kilometers with a height of hundreds of meters and a length of sometimes thousands of kilometers with a slight slope to the surface of the Earth. An atmospheric front passing through certain territory, the weather changes dramatically. Among the atmospheric fronts, a distinction is made between warm and cold fronts(Fig. 14)

Rice. 14

Warm front is formed when warm air actively moves towards cold air. Then warm air flows onto the retreating cold wedge and rises along the interface plane. As it rises, it cools. This leads to condensation of water vapor, the formation of cirrus and nimbostratus clouds and precipitation. With the arrival of a warm front, atmospheric pressure decreases, which is usually associated with warming and heavy, drizzling precipitation.

Cold front formed when cold air moves towards warm air. Cold air, being heavier, flows under the warm air and pushes it upward. In this case, stratocumulus rain clouds appear, from which precipitation falls in the form of showers with squalls and thunderstorms. The passage of a cold front is associated with colder temperatures, stronger winds and increased air transparency. Great importance have weather forecasts. Weather forecasts are made on different time. Usually the weather is predicted for 24 - 48 hours. Making long-term weather forecasts is associated with great difficulties.

Climate- long-term weather regime characteristic of a given area. Climate influences the formation of soil, vegetation, and fauna; determines the regime of rivers, lakes, swamps, influences the life of seas and oceans, and the formation of relief.

The distribution of climate on Earth is zonal. There are several climate zones on the globe.

Climate zones— latitudinal strips of the earth’s surface that have a uniform air temperature regime, determined by the “norms” of solar radiation arrival and the formation of similar air masses with the characteristics of their seasonal circulation (Table 2). Air masses- large volumes of troposphere air that have more or less identical properties (temperature, humidity, dust, etc.). The properties of air masses are determined by the territory or water area over which they are formed.

Characteristics of zonal air masses:

equatorial - warm and humid;

tropical - warm, dry;

temperate - less warm, more humid than tropical, characterized by seasonal differences;

Arctic and Antarctic - cold and dry.

Table 2.Climate zones and air masses operating in them

Climate zone	Effective zonal air masses
	In summer	in winter
Equatorial	Equatorial
Subequatorial	Equatorial	Tropical
Tropical	Tropical
Subtropical	Tropical	Moderate
Moderate	Temperate latitudes (polar)
Subarctic Subantarctic	Moderate	Arctic Antarctic
Arctic Antarctic	Arctic Subantarctic

Within the main (zonal) types of VMs, there are subtypes: continental (forming over the continent) and oceanic (forming over the ocean). An air mass is characterized by a general direction of movement, but within this volume of air there can be different winds. The properties of air masses change. Thus, marine temperate air masses carried by westerly winds to the territory of Eurasia, when moving eastward, gradually warm up (or cool), lose moisture and turn into continental temperate air.

Climate-forming factors:

• the geographic latitude of the place, since the angle of inclination of the sun’s rays, and therefore the amount of heat, depends on it;
• atmospheric circulation - prevailing winds bring certain air masses;
• ocean currents (see about precipitation);
• absolute altitude of the place (with altitude the temperature decreases);
• distance from the ocean - on the coasts, as a rule, there are less sharp temperature changes (day and night, seasons of the year); more precipitation;
• relief (mountain ranges can trap air masses: if a moist air mass encounters mountains on its way, it rises, cools, moisture condenses and precipitation occurs).

Climatic zones change from the equator to the poles, as the angle of incidence of the sun's rays changes. This, in turn, determines the law of zoning, i.e. the change in the components of nature from the equator to the poles. Within climate zones, climatic regions are distinguished—parts of a climate zone that have a certain type of climate. Climatic regions arise due to the influence of various climate-forming factors (peculiarities of atmospheric circulation, the influence of ocean currents, etc.). For example, in the temperate climate zone of the Northern Hemisphere, areas of continental, temperate continental, maritime and monsoon climates are distinguished.

General atmospheric circulation- a system of air currents on the globe that promotes the transfer of heat and moisture from one area to another. Air moves from areas of high pressure to areas of low pressure. Areas of high and low pressure are formed as a result of uneven heating of the earth's surface. Under the influence of the Earth's rotation, air flows are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. In equatorial latitudes, due to high temperatures, there is a constant belt of low pressure with weak winds. Heated air rises and spreads at altitude to the north and south. At high temperatures and upward air movement, with high humidity, large clouds form. Falls out here a large number of precipitation.

Approximately between 25 and 30° N. and Yu. w. the air descends to the surface of the Earth, where, as a result, high pressure belts are formed. Near the Earth, this air is directed towards the equator (where there is low pressure), deviating to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This is how trade winds are formed. In the central part of the high pressure belts there is a calm zone: the winds are weak. Thanks to downward air currents, the air dries out and warms up. The hot and dry regions of the Earth are located in these belts.

In temperate latitudes with centers around 60° N. and Yu. w. pressure is low. The air rises and then rushes to the polar regions. In temperate latitudes, westerly air transport predominates (the deflecting force of the Earth's rotation acts).

Polar latitudes are characterized by low air temperatures and high pressure. Air coming from temperate latitudes descends to the Earth and is again directed to temperate latitudes with northeastern (in the Northern Hemisphere) and southeastern (in the Southern Hemisphere) winds. There is little precipitation (Fig. 15).

Rice. 15. Scheme of the general circulation of the atmosphere

Indicators of thermal air conditions

The main indicators of air temperature are the following:

1. Average temperature of the day.

2. Average daily temperature by month.

3.Average temperature of each month.

4. Average long-term temperature of the month. All average long-term data are displayed over a long period (at least 35 years). Data from January and July are most often used. The highest long-term monthly temperatures are observed in the Sahara (up to + 36.5 0 C) and in Death Valley (up to +39 0 C). The lowest temperatures are recorded at Vostok station in Antarctica (up to – 70 0 C).

5.Average temperature each year.

6. Average long-term temperature of the year. The highest average annual temperature was recorded at the Dallol weather station in Ethiopia and amounted to +34.4 0 C. In the south of the Sahara, many points have an average annual temperature of +29-30 0 C. The lowest average annual temperature was recorded at the Station plateau and amounted to – 56.6 0 C .

7. Absolute minimums and maximums of temperature for any observation period - day, month, year, series of years. The absolute minimum for the entire earth's surface was noted at Vostok station in Antarctica in August 1960 and amounted to -88.3 0 C, for the northern hemisphere - in Oymyakon in February 1933 (-67.7 0 C).

The highest temperature for the entire Earth was observed in September 1922 in El Asia in Libya (+57.8 0 C). The second heat record of +56.7 0 C was recorded in Death Valley. In third place in terms of this indicator is the Thar Desert (+53 0 C).

In the sea, the highest water temperature +35.6 0 C was recorded in Persian Gulf. Lake water heats up most in the Caspian Sea (up to +37.2 0 C).

If the thermal regime of the geographic envelope was determined only by the distribution of solar radiation without its transfer by the atmosphere and hydrosphere, then at the equator the air temperature would be 39 0 C, and at the pole -44 0 C. Already at a latitude of 50 0 N. and S. a zone of eternal frost would begin. However, the actual temperature at the equator is about 26 0 C, and at the north pole -20 0 C.

Up to latitudes 30 0 solar temperatures are higher than actual ones, i.e. excess solar heat is generated in this part of the globe. In middle, and even more so in polar latitudes, actual temperatures are higher than solar ones, i.e. These belts of the Earth receive additional heat from the sun. It comes from low latitudes with oceanic (water) and tropospheric air masses in the process of their planetary circulation.

Thus, the distribution of solar heat, as well as its absorption, occurs not in one system - the atmosphere, but in a system of a higher structural level - the atmosphere and hydrosphere.

Analysis of heat distribution in the hydrosphere and atmosphere allows us to draw the following general conclusions:

1.Southern Hemisphere colder than the north, since there is less advective heat from the hot zone.

2. Solar heat is spent mainly over the oceans to evaporate water. Together with steam, it is redistributed both between zones and within each zone, between continents and oceans.

3. From tropical latitudes, heat enters equatorial latitudes with trade wind circulation and tropical currents. The tropics lose up to 60 kcal/cm2 per year, and at the equator the heat gain from condensation is 100 or more cal/cm2 per year.

4. The northern temperate zone receives up to 20 or more kcal/cm2 per year from warm ocean currents coming from equatorial latitudes (Gulf Stream, Kurovivo).

5.Western transfer from the oceans transfers heat to the continents, where temperate climate is formed not to latitude 50 0, but much north of the Arctic Circle.

6. In the southern hemisphere, only Argentina and Chile receive tropical heat; The cold waters of the Antarctic Current circulate in the Southern Ocean.

In January, a huge area of ​​positive temperature anomalies is located in the North Atlantic. It extends from the tropics to 85 0 N latitude. and from Greenland to the Yamal-Black Sea line. The maximum excess of actual temperatures above the mid-latitude one reaches in the Norwegian Sea (up to 26 0 C). The British Isles and Norway are 16 0 C warmer, France and the Baltic Sea are 12 0 C warmer.

In Eastern Siberia in January, an equally large and pronounced area of ​​negative temperature anomalies is formed with the center in North-Eastern Siberia. Here the anomaly reaches -24 0 C.

There is also an area of ​​positive anomalies (up to 13 0 C) in the northern part of the Pacific Ocean, and negative anomalies (up to -15 0 C) in Canada.

Heat distribution on the earth's surface on geographical maps using isotherms. There are isotherm maps for the year and each month. These maps fairly objectively illustrate the thermal regime of a particular area.

Heat on the earth's surface is distributed zonally and regionally:

1. The average long-term highest temperature (27 0 C) is observed not at the equator, but at 10 0 N latitude. This warmest parallel is called the thermal equator.

2. In July, the thermal equator shifts to the northern tropic. The average temperature at this parallel is 28.2 0 C, and in the hottest areas (Sahara, California, Tar) it reaches 36 0 C.

3. In January, the thermal equator shifts to the southern hemisphere, but not as significantly as in July to the northern. The warmest parallel (26.7 0 C) on average turns out to be 5 0 S, but the hottest areas are located even further south, i.e. on the continents of Africa and Australia (30 0 C and 32 0 C).

4. The temperature gradient is directed towards the poles, i.e. The temperature decreases towards the poles, more significantly in the southern hemisphere than in the northern. The difference between the equator and North Pole is 27 0 C in winter 67 0 C, and between the equator and the South Pole 40 0 ​​C in summer, 74 0 C in winter.

5.The temperature drop from the equator to the poles is uneven. In tropical latitudes it occurs very slowly: at 1 0 latitude in summer 0.06 - 0.09 0 C, in winter 0.2 - 0.3 0 C. All tropical zone in terms of temperature it turns out to be very homogeneous.

6. In the northern temperate zone, the course of January isotherms is very complex. Analysis of isotherms reveals the following patterns:

In the Atlantic and Pacific Oceans significant heat advection associated with the circulation of the atmosphere and hydrosphere;

Land adjacent to the oceans - Western Europe and North-West America - have a high temperature (on the coast of Norway 0 0 C);

The huge landmass of Asia is very cold, with closed isotherms outlining a very cold area in Eastern Siberia, up to – 48 0 C.

Isotherms in Eurasia do not go from West to East, but from northwest to southeast, showing that temperatures fall in the direction from the ocean inland; the same isotherm passes through Novosibirsk as across Novaya Zemlya (-18 0 C). The Aral Sea is as cold as Spitsbergen (-14 0 C). A similar picture, but somewhat weakened, is observed in North America;

7. July isotherms follow a fairly straight line, since the temperature on land is determined by solar insolation, and the transfer of heat across the ocean (Gulf Stream) in summer does not noticeably affect the temperature of land, since it is heated by the Sun. In tropical latitudes, the influence of cold ocean currents is noticeable, running along the western coasts of the continents (California, Peru, Canary, etc.), which cool the adjacent land and cause the deviation of isotherms towards the equator.

8. In the distribution of heat across the globe, the following two patterns are clearly expressed: 1) zoning, due to the figure of the Earth; 2) sectorality, due to the peculiarities of the absorption of solar heat by oceans and continents.

9. The average air temperature at the level of 2 m for the entire Earth is about 14 0 C, in January 12 0 C, in July 16 0 C. The southern hemisphere is colder than the northern hemisphere in annual terms. The average air temperature in the northern hemisphere is 15.2 0 C, in the southern hemisphere – 13.3 0 C. The average air temperature for the entire Earth coincides approximately with the temperature observed around 40 0 ​​N latitude. (14 0 C).

Solar heat and light are distributed unevenly over the surface of the spherical Earth. This is explained by the fact that the angle of incidence of the rays is different at different latitudes.

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

When the Earth faces the Sun with its North Pole, it illuminates and heats the Northern Hemisphere more. The days are getting longer than the nights. The warm season is coming - summer. At the pole and in the subpolar part, the Sun shines around the clock and does not set beyond the horizon (Night does not fall). This phenomenon is called polar day. At the pole it lasts 180 days (six months), but the further you go south, the duration decreases to a day at parallel 66.5 0 mon. w. This parallel is called the Arctic Circle. To the south of this line, the Sun descends below the horizon and the change of day and night occurs in the order familiar to us - every day. June 22 - The sun's rays will fall vertically (at the greatest angle - 90 0) to parallel 23.5 mon. w. This day will be the longest and the shortest night of the year. This parallel is called the Northern Tropics, and June 22 is the summer solstice.

Currently, the South Pole is distracted from the Sun and it illuminates and heats the Southern Hemisphere less. It's winter there. To the pole and subpolar part during the day Sun rays They don't hit at all. The sun does not appear over the horizon and the day does not come. This phenomenon is called polar night. At the pole itself it lasts 180 days, and the further north you go, the shorter it becomes, up to one day at parallel 66.5 0 S. w. This parallel is called the Antarctic Circle. To the north of it, the Sun appears on the horizon and the change of day and night occurs every day. June 22nd will be the shortest day of the year. For the Southern Hemisphere it will be the winter solstice.

Three months later, on September 23, the Earth will take a position relative to the Sun when the sun's rays equally illuminate both the Northern and Southern Hemispheres. The sun's rays fall vertically at the equator. On the entire Earth, except for the poles, day is equal to night (12 hours each). This day is called the autumn equinox.

In another three months, on December 22, the Southern Hemisphere will return to the Sun. Summer will come there. This day will be the longest, and the night will be the shortest. There will be a polar day in the subpolar region. The rays of the Sun fall vertically on the parallel 23.5 0 south. w. But in the Northern Hemisphere it will be winter. This day will be the shortest, and the night will be the longest. Parallel 23.5 0 S. w. is called the Tropic of the South, and December 22 is the winter solstice.

In another three months, on March 21, again both hemispheres will be illuminated equally, day will be equal to night. The sun's rays fall vertically on the equator. This day is called the spring equinox.

In Ukraine highest height The sun at noon is 61–69 0 (June 22), the lowest is 14-22 0 (December 22).

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

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

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

The sun's rays passing through the atmosphere heat it up little. The atmosphere is heated by the Earth's surface, which absorbs solar energy and converts it into heat. Air particles coming into contact with a heated surface receive heat and carry it into the atmosphere. This heats up the lower layers of the atmosphere. Obviously, the more solar radiation the Earth's surface receives, the more it heats up, and the more the air heats up from it.

Air temperature is measured with thermometers (mercury and alcohol). Alcohol thermometers are used when the air temperature is below - 38 ° C. At meteorological stations, thermometers are placed in a special booth, built from separate plates (blinds) located at a certain angle, between which air circulates freely. Direct sunlight does not reach the thermometers, so the air temperature is measured in the shade. The booth itself is located at a height of 2 m from the earth's surface.

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

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

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

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

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

There is a lot of precipitation over coastal areas, and as you move away from the oceans, their amount decreases. There is more precipitation on the windward slopes of mountain ranges and significantly less on the leeward ones. For example, on the Atlantic coast of Norway in Bergen, 1730 mm of precipitation falls per year, and in Oslo (beyond the ridge - approx. site), there is an average of more than 11,000 mm of precipitation per year. Such an abundance of moisture brings to these places the humid summer southwest monsoon, which rises along the steep slopes of the mountains, cools and pours down with heavy rain.

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

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

The distribution of precipitation is also influenced by the currents of the World Ocean. Over areas near which warm currents pass, the amount of precipitation increases, since the warm water masses heat the air, it rises and clouds with sufficient water content form. Over areas near which cold currents pass, the air cools and sinks, clouds do not form, and much less precipitation falls.

Since water plays a significant role in erosion processes, it thereby affects the movements of the earth's crust. And any redistribution of masses caused by such movements under the conditions of the Earth rotating around its axis can, in turn, contribute to a change in the position of the Earth’s axis. During ice ages, sea levels drop as water accumulates in glaciers. This, in turn, leads to the expansion of continents and increased climatic contrasts. Reduced river flows and lower sea levels prevent warm temperatures from reaching ocean currents cold regions, leading to further climate changes.



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Slide captions:

Distribution of light and heat on Earth

Find the match: Climate Weather a) average annual precipitation b) average daily temperature c) wind direction and speed d) wind rose e) type of precipitation f) cloudiness g) average long-term temperature h) temperature of the warmest and coldest month

Why do seasons change on Earth?

Solstice (summer solstice and winter solstice) Moments when the height of the Sun above the horizon at noon is greatest (summer solstice, June 22) or least (winter solstice, December 22). In some years, the solstice shifts to the 21st, as the duration calendar year varies (365 or 366 days).

Summer solstice per day summer solstice the most long duration day in the Northern Hemisphere, the entire region beyond the Arctic Circle is illuminated, the Sun does not set. In the Southern Hemisphere, at this time the day is shortest, the entire region beyond the Arctic Circle is in shadow, the Sun does not rise.

Winter solstice Per day winter solstice the picture is the opposite: the shortest day in the Northern Hemisphere, the longest in the Southern Hemisphere. On days close to the solstice, the length of the day and the midday altitude of the Sun change little, hence the term “solstice.”

Equinox (spring equinox and autumn equinox) Moments when the sun's rays touch both poles and the earth's axis is perpendicular to the rays. The vernal equinox occurs on March 21, autumn equinox - September 23; in some years the equinox shifts to the 22nd. The Northern and Southern Hemispheres are illuminated equally, at all latitudes day is equal to night, the Sun rises at one pole and sets at the other.

Tropics Tropics - the Northern Tropic and the Southern Tropic - parallel, respectively, with northern and southern latitudes of about 23.5°. On the day of the summer solstice (June 22), the Sun at noon is at its zenith over the Tropic of Cancer, or the Tropic of Cancer; On the day of the winter solstice (December 22) - over the Southern Tropic, or Tropic of Capricorn. At any latitude between the tropics, the Sun is at its zenith twice a year; North of the Northern Tropic and south of the Southern Tropic, the Sun does not reach its zenith.

Arctic Circles The Arctic Circles (Arctic Circle and Antarctic Circle) are parallels with northern and southern latitudes, respectively, about 66.5°. 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.

Obelisk to the Arctic Circle Residents of Salekhard can be proud of their unique geographical location of your city. The fact is that Salekhard is located on the Arctic Circle line and is divided into two parts by it. In the center of the city, on the symbolic dividing line, there is the world's only obelisk to the Arctic Circle.

Polar day Polar day is a period when the Sun in high latitudes does not fall below the horizon around the clock. 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. Latitude Duration of the polar day Duration of the polar night 66.5° 1 1 70° 64 60 80° 133 126 90° 186 179 Duration of the polar day and polar night at different latitudes of the Northern Hemisphere (days).

Polar night 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. Latitude Duration of the polar day Duration of the polar night 66.5° 1 1 70° 64 60 80° 133 126 90° 186 179 Duration of the polar day and polar night at different latitudes of the Northern Hemisphere (days).

Light belts Light belts are parts of the Earth's surface limited by the tropics and polar circles and differing in light conditions. Between the tropics is the tropical zone; here twice a year (and in the tropics - once a year) you can observe the midday Sun at its zenith. From the Arctic Circle to the Pole, there are polar belts in each hemisphere; There are polar days and polar nights here. In the temperate zones, located in the Northern and Southern Hemispheres between the tropics and the Arctic Circle, the Sun does not reach its zenith, and polar day and polar night are not observed.

Illumination belts Name of the belt Characteristics of the belt Boundaries between the belts North polar Polar night and polar day observed 66.5° N. - Arctic Circle 23.5° N - Northern Tropic 23.5° S. - Southern Tropic 66.5° S. - Antarctic Circle Northern temperate There is neither a polar day nor a polar night, the Sun is never at its zenith The Tropical Sun is at its zenith twice a year at any latitude and once at the latitude of the tropics Southern temperate The Sun is never at its zenith, not there is neither a polar day nor a polar night South polar A polar night and a polar day are observed

Fill out the table Date Northern Hemisphere Southern Hemisphere June 22 Day ... night At parallel 23.5°N. -... On the parallel 66.5° N -... Day... night On the parallel 23.5° S. -... At the parallel 66.5° S -... September 23 1. Day... night 2. At the equator... 1. Day... night 2. At the equator... December 22 Day... night At the parallel 23.5°N . -... On the parallel 66.5° N -... Day... night On the parallel 23.5° S. -... At the parallel 66.5° S -... March 21 1. Day... night 2. At the equator... 1. Day... night 2. At the equator...

Checking Date Northern Hemisphere Southern Hemisphere June 22 Summer Solstice Day Longer than night At parallel 23.5° N. The sun is at its zenith At the parallel 66.5° N latitude - polar day Winter solstice Day The day is shorter than the night At the parallel 66.5° S latitude – polar night September 23 Day is equal to night At the equator – the Sun is at its zenith Day is equal to night At the equator – the Sun is at its zenith December 22 A day is shorter than night At 66.5° N. latitude. – polar night The day is longer than the night At 23.5° S. The sun is at its zenith At 66.5° S. – polar day March 21 Day is equal to night At the equator the Sun is at its zenith Day is equal to night At the equator the Sun is at its zenith