Under the influence of what factors the climate of Eurasia is formed. Eurasia mainland. Total solar radiation

The climatic features of the mainland are determined by its huge size, large extent from south to north (from the equator to the Arctic latitudes), from west to east, as well as the structure of the surface - the presence of high mountain systems in the south and east, the wide distribution of basin relief.

Due to its great length from north to south, Eurasia is located in all climatic zones of the Northern Hemisphere: from the Arctic to the equatorial. The temperate zone occupies the largest areas, because it is in temperate latitudes that the mainland is more elongated from west to east.

In the arctic and subarctic zones, western regions with a maritime climate are distinguished: small temperature amplitudes due to relatively warm winters and cool summers. In the east of the belts, the climate is continental with very cold (down to -40 ... -45 ° C) winters.

Within the temperate zone, climatic conditions are very diverse. The climate of the western coast is maritime, it is formed during the year under the influence of air masses from the Atlantic Ocean. Summers are cool, winters are relatively warm even in northern latitudes, for example, on the coast of the Scandinavian Peninsula. Precipitation falls throughout the year. During the passage of cyclones, the weather changes rapidly, in summer there may be cold snaps, in winter thaws.

Some features of the maritime type of climate persist further to the east, almost throughout Europe: weather instability, relatively wet winters. However, with distance from the ocean, the difference between summer and winter temperatures increases: winter becomes noticeably colder. There is more precipitation in summer than in winter. This is an area of transition from maritime to continental climate. Often this type of climate is called temperate continental. Transitional conditions are typical for Central and Eastern Europe.

Beyond the Urals, in Siberia, and Central Asia, winters are very cold and dry; summers are hot and moderately humid. This area has a sharply continental climate.

On the east coast of the mainland, the climate is monsoonal with relatively warm, humid summers and cold, dry winters.

In the subtropical zone on the plains, temperatures are positive throughout the year. There are three climatic regions. In the west - the Mediterranean, where dry tropical air reigns in summer (heat and cloudless), and in winter - sea air of temperate latitudes (precipitation falls).

In the regions of the Asian highlands, the climate is subtropical continental with relatively cold (in places with temperatures below 0 ° C) winters and hot, very dry summers. The total amount of precipitation is small, they fall in the winter-spring period.

In the east of the subtropical zone there is an area of monsoon climate with a typical precipitation regime (summer maximum).

The climatic features of the tropical zone are peculiar. On the Arabian Peninsula, in Mesopotamia, in the south of the Iranian Highlands and in the basin of the lower Indus, continental tropical air masses dominate during the year, very dry and hot. Summers are very hot (average July temperatures are +30°...+35°С), winters are warm (average January temperatures are +18°...+24°С). The amount of precipitation on the plains does not exceed 200 mm, and in some places - below 50 mm per year.

To the east, the tropical belt becomes wedge-shaped. At 10-20°C. sh. it is replaced by a subequatorial belt with a monsoon climate prevailing on the peninsulas of Hindustan, Indochina, in most of the Indo-Gangetic lowland and in the very south of China.

To the south is the equatorial belt. It occupies the Malay Peninsula and the islands of the Malay Archipelago. The climate is the same as in the Amazonian lowlands and in the basin of the Congo River.

In the climate Eurasia shows features associated with the huge size of its territory. The position of the main part of the mainland between the equator and the Arctic Circle, the massiveness of the eastern and central parts, the dissection of the western and southern margins, the influence of ocean basins, and the complex structure of the surface create an exceptional variety of climatic conditions in Eurasia.

Annual total radiation in Eurasia, it varies within the following limits (Fig. 5): on the Arctic islands it is 2520 MJ / m 2 (60 kcal / cm 2), in the western part of Europe - from 2940 to 5880 (from 70 to 140), in the south and south -East of Asia - 5000-7570 (120-180), and in Arabia reaches the maximum value on Earth - 8400-9240 (200-220).

Rice. 5. Total solar radiation per year

The annual radiation balance varies within Eurasia from 420 to 3360 MJ/m 2 (10-80 kcal/cm 2). In January, north of the line Brittany - the north of the Adriatic - the center of the Black Sea - the south of the Caspian - the north of the Korean peninsula - the north of the Japanese islands, the radiation balance is negative (Fig. 6).

Rice. 6. Radiation balance for the year

Main atmospheric process for most of Eurasia - west-east transport and associated cyclonic activity. With the western transfer to the mainland throughout the year, air enters from the Atlantic Ocean and spreads to its eastern outskirts. As it moves east, the Atlantic air transforms, giving off moisture, cooling in winter and warming up in summer. Due to the large horizontal dissection of the western part of Eurasia and the absence of sharp orographic obstacles, the process of transformation of air masses over Europe is relatively slow, and therefore climatic conditions change gradually. Only beyond the Urals, within Asia, is the predominance of continental air masses observed throughout the year. Sharp contrasts in heating and in pressure conditions between the mainland and the Pacific Ocean, intensified by the peculiarities of the orography of Central and East Asia, determine the monsoon circulation typical of the east of Eurasia, which is most pronounced here in comparison with all other regions of the Earth. The circulation over the southern parts of Eurasia also has a monsoon character, only here it manifests itself in the interaction between the mainland and the Indian Ocean.

Consider how meteorological conditions change in Eurasia by season.

in winter the contrasts in heating and pressure distribution over the mainland, on the one hand, and the Atlantic and Pacific oceans, on the other, are especially pronounced. The January isobar maps over Eurasia and neighboring oceanic basins clearly show the following baric regions ( rice. 7).

Rice. 7. Air pressure and winds in January

In the northern part of the Atlantic Ocean there is a closed area of low pressure(North Atlantic, or Icelandic, low), due to the influence of the warm North Atlantic current and the frequent passage of deep cyclonic depressions moving from the coast of North America to the east. Due to the influence of the warm current and the deep penetration of sea basins into the interior of the continent, the reduced pressure also extends to the southern part of the Arctic Ocean and the western coast of Europe.

The boundaries of the greatest distribution of floating ice (in March, April - for the northern hemisphere, in September for the southern hemisphere) Areas for which the values of the radiation balance have not been determined: mountainous areas

To the south, 30° N, there is high pressure area(North Atlantic, or Azores, maximum), which is part of the subtropical high pressure zone of the northern hemisphere. The interaction of these baric regions is of particular importance for the formation of meteorological conditions in Europe. The air flowing along the northern and eastern periphery of the North Atlantic Maximum is drawn into the area of low pressure over the North Atlantic and the western margin of Europe, creating in temperate latitudes a system of cyclonic winds of the western and southwestern direction, blowing from the relatively warm ocean to the mainland and bringing a lot of moisture. In the polar latitudes, winds with an easterly component prevail at this time. The main routes of movement of cyclonic depressions in winter pass through Iceland, the Scandinavian Peninsula and the Barents Sea. Over the waters of the Mediterranean Sea, which accumulate a large amount of heat, local cyclogenesis develops in winter. Most often, cyclones form over the Ligurian Sea and the Gulf of Lion, over the southern part of the Tyrrhenian Sea and the island of Cyprus. From here they head east and northeast, penetrating in some years up to the Indus Valley.

Passage of cyclones in Europe it is accompanied by cloudy weather with rain or sleet, typical of the Western European winter. Often the sea air of temperate latitudes is replaced by arctic air, causing a sharp decrease in temperature and a decrease in precipitation. Arctic air spreads to the south, but relatively rarely penetrates into the southern part of Europe, as it is delayed by sublatitudinally located mountain ranges. The farther to the east, the more frequent and longer the arctic air intrusions.

When driving western air flow over the continent is its cooling and drying. In the interior regions of Asia, in connection with the cooling of the surface layers of the atmosphere, an area of increased pressure is created, above which a hollow is formed in the upper troposphere. Transformed air coming from the west is drawn into this hollow, cools and settles, replenishing the high pressure area in the surface layers. The influence of the relief of the inner parts of Asia also has an effect: high mountain structures rising south of the maximum formation region prevent the spread of cold air masses and contribute to their concentration in a relatively limited space. As a result of the interaction of all these processes, the largest high-pressure area on Earth, the Asian quasi-stationary maximum, is created over the interior of Eurasia in winter.

Along the northern and eastern periphery of this maximum, cold and dry continental air flows towards the Pacific Ocean, which is warmer at this time. The resulting northerly and northwesterly winds are known as the winter monsoon.

Asian High can form a spur, which sometimes extends as far as Western Europe, causing severe cooling there.

Southern Asia in winter it is under the influence of the trade wind circulation. The Arabian Peninsula, together with the neighboring Sahara, is influenced by the eastern periphery of the North Atlantic High and the dry northern winds associated with it. Over Hindustan and Indochina, on the island of Sri Lanka, the Philippines and in the north of the Sunda Islands, the northeast trade wind dominates, flowing from the North Pacific maximum towards the equatorial trough, shifted to the south at this time. In the countries of South and Southeast Asia, it is called the winter monsoon.

Despite the negative radiation balance north of 39-40° N, in areas, adjacent to the Atlantic Ocean, the average January temperature is much higher than 0 ° C, since in winter the Atlantic air is a relatively warm air mass. The January isotherms extend submeridionally over most of the temperate zone of Eurasia and take a sublatitudinal direction only to the east of the Yenisei (Fig. 8).

Rice. 8. Average air temperature in Eurasia at ground level (January)

off the west coast In the Scandinavian Peninsula, the zero isotherm of January rises up to 70° N, fixing the highest positive anomaly of mid-latitude winter temperatures (over 20°). The farther to the east, the lower the average winter temperature becomes. Already in the eastern part of foreign Europe, it acquires a negative value.

Atlantic air brings a large amount of moisture to land, which falls in the west of Europe in the form of rain or sleet. Especially a lot of precipitation occurs on the mountain slopes of the western exposure. Winter cyclonic precipitation is also characteristic of the Mediterranean coast and the western regions of Asia. Their number sharply decreases from west to east due to the weakening of frontal activity in the inner parts of the continent.

In most of overseas Asia in winter precipitation missing. In the interior, this is due to the anticyclonic state of the atmosphere and strong supercooling of the surface. On the eastern edge of the mainland, the reason for the lack of precipitation is the continental monsoon, which carries dry cold air towards the ocean. In this regard, Central and East Asia is characterized by low winter temperatures with a pronounced negative anomaly, which is felt up to the tropic, where temperatures can drop to 0 °C. In the north, the average January temperature is -20, -25 °C.

In the southern peninsulas and islands of Asia, where trade winds operate in winter, dry weather also prevails. Precipitation occurs only in those areas where the trade winds or northern winds bring enough moisture (windward slopes of the Philippine Islands, the southeastern tip of Hindustan and the islands of Sri Lanka). On the Sunda Islands, located on the equator and south of it, convective rain falls. The January temperature in the entire southern part of Asia is high: 16 ... 20 ° C, on the islands of the Malay Archipelago it reaches 25 ° C in places.

Summer meteorological conditions in Eurasia and its neighboring oceans are changing significantly. The Asian maximum disappears, and low pressure sets in over the heated continent with a closed center in the Indus River basin and on the shores of the Persian Gulf (South Asian Low). It is the northern margin of the equatorial trough, which in Eurasia extends farthest from the equator (up to 22-28° N). The pressure rises towards the oceans. The Iceland Low is weakening and the North Pacific Low is disappearing. An area of high pressure persists over the polar basin. The North Atlantic and North Pacific highs intensify and widen to the north. In the Indian Ocean, south of the tropic, the South Indian High grows in the winter season of the southern hemisphere. This distribution of pressure in the surface layers of the atmosphere creates conditions for the transfer of air masses to Eurasia from the surrounding oceans ( rice. nine).

Rice. 9. Air pressure and winds in July

In the northwest of Europe, between the area of high pressure in the Arctic and the spur of the North Atlantic High, there is a band of relatively low pressure. Cyclonic activity associated with the Arctic front takes place within its limits. In this regard, western and northwestern winds prevail, which carry relatively cold air from the ocean to the mainland. Over the warmed mainland, it quickly transforms into a continental one. At the same time, the marine Arctic masses are undergoing transformation. This increases not only the temperature, but also the moisture content of the air due to evaporation from the underlying surface. July isotherms in Europe extend sublatitudinally everywhere, with a slight deviation to the south near the coast of the ocean. The average July temperature in the west varies from north to south from 12 to 24 °С, in the east it sometimes reaches 26...28 °С (Fig. 10).

Rice. 10. Average air temperature in Eurasia at ground level (July)

Summer in Europe rains are less plentiful than in winter, as cyclonic activity weakens. In Southern Europe and Western Asia, where winds blow from the eastern periphery of the North Atlantic High, carrying tropical air, there is almost no precipitation.

Ascending the average July temperature and a decrease in precipitation due to the transformation of the Atlantic air when moving from west to east is felt almost throughout the mainland. It is especially dry and hot in the inner parts of the mainland (Central Asia), protected by mountain rises from moist air currents from the oceans. Dryness and high temperatures (average July up to 32 ° C) are also characteristic of most of the Arabian Peninsula, which is under the influence of the northeast trade wind flowing from the North Atlantic High.

In other conditions are eastern and southern suburbs mainland adjacent to the Pacific and Indian oceans. The temperature and baric contrasts between them and the vast landmass of Eurasia are especially strong in summer. Humid and relatively cold air enters Asia along the western periphery of the Pacific High. As a result of its interaction with continental air masses, heavy rain showers fall. This air current is called the summer monsoon in East Asia.

In the south of Asia(Indostan, Indochina) the role of the summer monsoon is played by the flow of equatorial air, carrying huge masses of moisture from the Indian Ocean. Due to the configuration and size of Eurasia and the expansion of the equatorial trough, the equatorial air in the form of a monsoon of the prevailing southwesterly direction penetrates very far to the north. Where the monsoon flow meets mountain rises, precipitation is especially abundant (for example, on the southeastern slopes of the Himalayas, on the southern slope of the Shillong massif, in Cherrapunji, the maximum amount of precipitation on the globe is recorded - 10719 mm per year, etc.). On equatorial islands, convective intramass precipitation is of great importance (Fig. 11).

Rice. 11. Average annual precipitation in Eurasia, mm

In the Pacific and Indian Oceans Every year from June to November, tropical cyclones, or typhoons, are born, bringing great disasters to the population of the countries of East and South Asia. These are the strongest cyclonic eddies, the speed of which over the open ocean in exceptional cases can reach 100 km/h (usually 30-50 km/h). They are accompanied by downpours, during which 150 mm of precipitation or more can fall. On the coasts, surge waves pose a great threat, which, together with showers, cause catastrophic floods. The Philippines and the Japanese islands are especially affected by typhoons, but sometimes the disaster also captures the outskirts of the continent up to the south of the Far East. In the Indian Ocean, tropical cyclones move north and northwest to the northern coasts of the Bay of Bengal and the Arabian Sea.

According to its size and geographical position, Eurasia with the islands adjacent to it is located in all climatic zones of the northern hemisphere, and within each zone all the climatic regions inherent in it are represented. Thus, we can say that in Eurasia there are all types of climates known on Earth.

northernmost islands Eurasia, and in the east and the strip of the mainland adjacent to the Arctic Ocean, are located within the Arctic zone. Of the foreign territories of Eurasia, the Arctic climate is typical for the Svalbard archipelago and small oceanic islands. Due to the geographical position and the influence of warm currents, the islands have a maritime arctic climate with relatively high winter temperatures (from -16 to -20 ° C) and a significant amount of precipitation (about 300 mm).

In a narrow strip, capturing Iceland and Scandinavia north of the Arctic Circle and expanding somewhat in the east, it crosses Eurasia subarctic belt. It is located between the summer and winter positions of the Arctic front and is characterized by the predominance of westerly circulation in summer and cold eastern Arctic winds in winter. In the west of Europe, especially in Iceland, the subarctic regions are characterized by relatively mild (-5, -10 °С) winters, cool (not more than 10 °С) summers and a large amount of precipitation (300-700 mm) falling in all seasons in the form of rain and snow.

The widest and most massive part of Eurasia lies within temperate climate zone, whose southern boundary, determined by the summer position of the polar front, runs from the southern coast of the Bay of Biscay through the middle of the Black and Caspian Seas to the northern part of the Korean Peninsula and the middle part of the island of Honshu. Despite the dominance of the west-east transfer throughout the year, the temperate zone within Eurasia is characterized by large differences in climatic conditions, which gives reason to consider it by region.

Region oceanic temperate warm climate includes the south of Iceland, the western outskirts of the Scandinavian Peninsula, the British Isles and the extreme west of the mainland - the Jutland Peninsula, the west and north of France. There are reasons to attribute the northwest of the Iberian Peninsula to this region of the temperate zone. Throughout the year, the Atlantic air, brought by the western winds, prevails there, and cyclonic activity is manifested. Winter is characterized by unstable rainy and foggy weather with an average temperature of the coldest month from 1 to 6 ° C, frosts and snowfalls are rare, and there is no stable snow cover. The average summer temperature is 10 ... 18 "C. Precipitation falls throughout the year, with a maximum in winter due to especially intense cyclonic activity. Annual precipitation in almost the entire region is more than 1000 mm, and evaporation does not exceed 800 mm per year. Therefore the Atlantic regions of Europe are characterized by excessive moisture ( rice. 12).

Rice. 12. The difference in precipitation and evaporation for the year

The climate of the rest of the temperate zone of Europe up to the Ural Mountains can be called transitional, from oceanic to continental. The most important role in climate formation belongs to the transformation of the Atlantic air and the ever-increasing influence of continental air masses that form over the mainland itself. Compared to the previous one, this area is characterized by less precipitation, large amplitudes of temperature fluctuations, and the presence of a frosty period of various durations. Within the area under consideration, more than in the previous one, differences between north and south are expressed. Scandinavia and Finland are characterized by long and severe winters. The Scandinavian mountains enhance the transformation of the Atlantic air and at the same time do not prevent the penetration of cold air masses from the Arctic. Therefore, the temperature in Sweden and Finland can drop to -40 °C, and in exceptional cases even to -50 °C, with an average January temperature of -10, -15 °C. Summer north of the 50th parallel is cool, with maximum precipitation at its beginning. Annual rainfall of 500 to 1000 mm with evaporation less than 600 mm provides excessive moisture throughout the year. The southern part of the region is characterized by less sharp temperature amplitudes, moderately cold winters with an average January temperature only slightly below 0 °C. The duration of snow cover and freeze-up on the rivers is short, it increases from west to east. Summer is warm, with an average July temperature of 12...20 °C. The maximum precipitation occurs in the first half of summer, evaporation increases to 800 mm, and moisture decreases compared to the northern regions.

A significant part of Asia within Russia, the countries of Central Asia, as well as Mongolia and Northwestern China (Gobi and Dzungaria) are located in the region continental climate temperate zone, which is under the influence of inland air masses all year round. Due to the influence of the Asian High, the region is characterized by cold winters with sharp temperature differences from place to place. With an average January temperature from -3 °С in the west of China to -12 °С in the north of Kazakhstan and -25 °С in Mongolia, in calm and cloudless weather, there are drops to -35 ... -50 °С. Due to persistent low winter temperatures and the almost complete absence of snow, permafrost develops in the eastern regions of the region. Almost the entire annual amount of precipitation (about 200 mm) falls in summer in the form of frontal rains. The average July temperature reaches 30 °C in the south of the region. Humidification is insufficient.

East of the Greater Khingan Range, including Northeast China, northern Korean Peninsula, Hokkaido and northern Honshu, climate monsoonal. This whole area is characterized by sharp differences in temperature, precipitation and moisture according to the seasons of the year. In winter, dry frosty weather prevails with strong winds blowing from the Asian High and raising a lot of dust. Only on the Japanese islands do heavy snows fall, since the continental air, passing over the relatively warm Sea of Japan, is saturated with moisture in the lower layers. In summer, the southeast monsoon blows, bringing humid unstable air from the southern and western periphery of the Pacific anticyclone. Approximately 70% of the annual amount of precipitation is associated with its arrival, falling in the form of showers at intervals of 4-5 days.

Subtropical the climatic zone also crosses Eurasia from the Atlantic to the Pacific. Within its limits, the west-east transfer in summer is replaced by tropical circulation. Of great importance is the system of mountain uplifts of High Asia, which in winter causes the splitting of the western transport stream into two branches - northern and southern. The latter passes south of the Himalayas, causing, according to G. N. Vitvitsky, a shift in comparison with other continents of the southern border of the subtropical belt in the direction of the equator.

The Iberian and Apennine Peninsulas, the south and west of the Balkan Peninsula, the west and south of Asia Minor, the eastern coast of the Mediterranean Sea, the Mediterranean islands, the south of the Crimean Peninsula and the north of Mesopotamia are in a subtropical climate with a dry summer ( Mediterranean). Summer dryness is associated with winds flowing along the eastern periphery of the extended North Atlantic High. The prevailing wind direction is northwest in the Western Mediterranean and northeast in the East. The average temperature in July is from 23 to 28 °C. With an almost complete absence of precipitation, the evaporation rate is 3-4 times higher than the actual evaporation. In winter, the Azores High shifts to the south and the Mediterranean falls into a system of westerly transport and cyclonic activity, with which 75-80% of the annual precipitation is associated. The average temperature of the coldest month increases from north to south from 4 to 12 °C. In the western part of the region of the Mediterranean climate, Atlantic air is predominant, in the east - continental. Therefore, when moving from west to east, the amount of precipitation decreases and the temperature amplitudes increase.

Inside the mainland, from the Iranian Plateau to the basin of the middle Yellow River, including the Tarim Basin, Beishan, the south of the Gobi and other regions of Central and Central Asia, the climate subtropical continental. This area is characterized by hot summers (25...35 °C) and cool winters with an average temperature above 0 °C, although in some years frosts can reach -20 °C. Precipitation is less than 200 mm per year, the air is very dry, the daily and annual temperature amplitudes are significant. In the rainfall regime, there are differences between west and east. In the west, winter precipitation is associated with the Iranian branch of the polar front and cyclonic activity. The east is dominated by summer precipitation brought by the southeast monsoon.

Special, extracontinental The climate of the highlands is characteristic of the interior regions of Asia (Tibet), which can be attributed to the subtropical zone only by geographical location, and not by actual climatic conditions. Due to the significant absolute heights, temperatures do not rise above 10 ... 15 ° C even in summer, in winter these areas are characterized by the same negative temperatures. The amount of precipitation, even in the most humid areas, does not exceed 500 mm per year, and in some places decreases to 100-150 mm, which causes aridity of the climate.

The climate of the eastern sector of the subtropical zone, as well as the temperate one, monsoonal. It extends to the Yangtze River basin and the southern part of the Japanese Islands. From the monsoon climate of the temperate zone, the subtropical monsoon climate is distinguished by a higher average winter temperature (from 4 to 8 ° C) and large annual precipitation, which exceeds 1000 mm and completely covers the evaporation rate. Winter dryness south of the Yangtze River valley is less pronounced than north of it, since there a front is created between the air flowing along the eastern periphery of the Asian high and the air of the southern branch of the western transport, and therefore rain falls. When the front breaks and the invasion of cold continental air to the south, up to the tropic, the temperature can drop to 0 °C. Noteworthy are the differences in winter conditions in the Mediterranean region and the Yangtze basin. In the first case, due to the direct influence of the Atlantic air, the winter is very warm with an average temperature of the coldest month from 10 to 12 ° C, in the second case, the average January temperature is almost twice as low, and significant drops are possible. This is due to the influence of the Asian high, the air of which is carried far to the south. In this regard, the southern border of the subtropical belt in East Asia has shifted almost to the tropic.

The diversity of climatic conditions in the expanses of Eurasia is explained by the huge size of the continent and its great length in all directions. In addition, the formation of the climate of the region was influenced by the massiveness of the central and eastern parts, and the strong dissection of the coastline in the west and south, and the pronounced influence of the oceans.

Total solar radiation

Within Eurasia, the amount of solar radiation reaching the Earth varies annually in the range from $60 \ kcal/cm^2$ (or $2520 \ MJ/m^2$) on the Arctic islands to $200-220 \ kcal/cm^2$ ( or $8400-9240 \ MJ/m^2$) in the Arabian Peninsula. In Western Europe, the amount of solar radiation is up to $140 \ kcal/cm^2$ ($5880 \ MJ/^2$) in Southeast Asia - up to $180 \ kcal/cm^2$ ($7570 \ 5880 \ MJ/m^2 $). The radiation balance in Eurasia is estimated at $10$ to $80\kcal/cm^2$ ($420-3360\MJ/m^2$). A part of the territory of Eurasia in winter is characterized by a negative radiation balance.

Atmospheric circulation

On the territory of most of Eurasia, western transport and cyclonic activity associated with it prevail. This causes a strong influence of the Atlantic Ocean on the climate of the mainland. Due to the absence of significant orographic obstacles up to the Urals on the path of the main transfer of air masses, they are slowly transformed and a gradual change in climate is observed. Further beyond the Urals, continental air masses dominate throughout the year. On the east, south and southeast coast of the mainland, monsoonal air circulation is observed.

Precipitation

Approximately $40 \ thousand km ^ 3 $ of precipitation falls on the surface of Eurasia during the year. The distribution of precipitation in Eurasia is largely determined by the characteristics of the atmospheric circulation.

Within the mainland, 2 areas of low rainfall are distinguished:

in the north of the mainland (Kola Peninsula, Yakutia), where the amount of precipitation is $100-400$ mm/year and decreases from west to east;
territories outside the sphere of influence of the Pacific, Indian and Atlantic oceans, covering almost half of the mainland. These are the interior of the Arabian Peninsula, the Iranian Plateau, the eastern part of the East European Plain, the West of Siberia and Central Siberia, Central Asia, the Tibetan Plateau, and the north of the Far East.

Atmospheric circulation also determines the amount of precipitation and the mode of precipitation.

seasonality

Climatic conditions of the regions of Eurasia in winter

In winter, there is a high contrast in the heating of the continent and oceans, and, accordingly, the distribution of atmospheric pressure. In January, the following baric regions are observed on the mainland:

The Icelandic Low is a closed area of low pressure in the North Atlantic Ocean (above Iceland).
The Azores High is an area of high pressure over the Atlantic ($30^\circ \ n.l.$), which is part of the area of the subtropical high pressure zone.

The interaction of these centers largely shapes the climate Europe. The air that flows along the northern and eastern periphery of the Azores High and forms relatively warm cyclonic winds of southwestern and western directions in temperate latitudes. In the polar latitudes, easterly winds blow predominantly at this time. Thus, cyclonic depressions pass through Iceland, Scandinavia and the Barents Sea in winter. At this time, over the Mediterranean Sea (especially the Gulf of Lion and the Ligurian Sea, the island of Cyprus and the south of the Tyrrhenian Sea) there is a local process of formation of cyclones. Cyclones formed over the Mediterranean Sea move east and northeast inland, sometimes reaching the Indus.

As we move east, the moist sea air dries up and cools. AT Central Asia these flows fall in the surface layers into the high pressure area, which is formed due to the cooling of the territory and high mountain systems along the perimeter of the area. This is how the largest area of high pressure on the planet is formed - the quasi-stationary Asian maximum. The action of this area can bring cooling even in Western Europe.

Due to the anticyclonic state of the atmosphere and severe hypothermia in the interior of Asia, up to tropical latitudes, there is practically no precipitation in winter and low air temperatures (up to $-30^\circ C$) are observed

AT South Asia trade winds dominate in winter. The western margins of South Asia may be affected by the North Atlantic High. Over Indochina, Hindustan, the Philippines, Sri Lanka and the Sunda Islands, the weather forms the northeast trade wind. It brings air masses from the North Pacific High. In winter, dry weather is also observed here, precipitation is typical for areas where sufficient moisture is brought with trade winds or westerly winds. This is the southeastern outskirts of Hindustan, part of the Philippine Islands. Winter temperatures here are moderate - up to $+20^\circ С$.

Climatic conditions of the regions of Eurasia in the summer

In the summer, the weather conditions of Eurasia are significantly different. Due to the warming of the territory, the Asian maximum is replaced by a low pressure area with a closed center over the Indus and the Persian Gulf - South Asian Low. The North Pacific Low is also disappearing, and the Icelandic Low is significantly weakening. Action North Atlantic and North Pacific Highs intensifies and spreads over large areas. Also formed South Indian High south of tropical latitudes. Above the polar latitudes, an area of high pressure remains.

AT northwestern Europe a band of relatively low pressure is formed with pronounced cyclonic activity, which forms western and northwestern winds, bringing relatively cold air to the mainland. Moving along the warmed mainland, it quickly becomes continental. The average temperature in July in this region varies almost sublatitudinally from $12$ to $26^\circ C$ when moving from north to south.

Western Asia and Southern Europe exposed to air masses from the periphery of the North Atlantic High. They bring dry tropical air.

In Central Asia, enclosed by mountain rises, dry and hot air prevails in summer, the average temperature in July is up to $30^\circ C$. Similar conditions develop over the Arabian Peninsula under the action of the northeast trade wind from the baric maximum in the North Atlantic Ocean.

South and East Asia in summer, they experience strong pressure and temperature contrasts between the mainland and the ocean. This results in torrential rainfall caused by the summer monsoons. These areas will receive the highest amount of precipitation on the planet.

In the summer, in the Indian and Pacific oceans, typhoons– cyclonic eddies with a speed of $30-50 \km/h$ (sometimes up to $100\km/h$). They bring heavy rainfall. The action of typhoons manifests itself mainly in the Japanese and Philippine Islands, sometimes occurs on the southern and eastern outskirts of the continent.

Remark 1

Thus, Eurasia is located in all climatic zones (due to the extension from north to south), and all climatic regions are represented on its territory (due to the extension from west to east). Within Eurasia, all known types of climate on the planet are represented.

The climatic features of Eurasia are determined by the huge size of the mainland, the great length from north to south, the variety of prevailing air masses, as well as the specific features of the structure of its surface and the influence of the oceans.

Due to the large extent of the mainland from north to south, due to different amounts in specific latitudes, Eurasia is located in all climatic zones of the northern hemisphere, from the arctic to the equatorial. The largest area in terms of area is occupied by the temperate zone, since it is in temperate latitudes that the mainland is most extended from west to east.

On, like other continents, relief has a great influence. The Alps, Himalayas and other mountains of the Alpine-Himalayan fold belt are an important climatic division of the mainland. They block the path of the cold and dry north to the south and at the same time stand as an insurmountable barrier to the warm and humid winds blowing from the south. So, in the basins, to the north of, 50-100 mm of precipitation falls per year, and at the foot of the eastern Himalayas - more than 10,000 mm per year. Winters in the countries of the European Mediterranean, beyond the barrier, are warm and relatively cold.

The influence of the oceans on the climate of Eurasia through the influence (, Kuril-Kamchatka, monsoon currents) and the sea air masses forming above them is well known and does not cause difficulties when considered in the exam.

Let us briefly dwell on the features and types of climate (climatic regions) on the territory of Eurasia.

In the subarctic and subarctic belts, areas are distinguished with a sea zone in the west of each zone: small temperature amplitudes due to relatively warm winters and cool summers (the influence of the branches of the North Atlantic Current). In the east of the belts, the climate is continental with very cold winters (up to -40 ... -45 ° С).

Within the temperate zone, stretching across the entire continent, there is a wide variety of climate types. The marine type of climate in the western regions of Europe is formed under the year-round influence of sea air masses from. Summers are cool here, winters are relatively warm even in northern latitudes on the coast. When passing through the Atlantic, it changes rapidly: in summer there may be cold snaps, in winter - thaws. The area of transitional climate from maritime to continental is mainly occupied by the territories of Central Europe. With distance from the ocean, the difference (amplitude) of summer and winter temperatures increases: winter becomes noticeably colder. There is more precipitation in summer than in the cold season. In the territory (up to the Urals), the climate is considered temperate continental. Beyond, and Central Asia, winters are very cold and dry, summers are hot and relatively humid. This is an area of sharply continental climate in the temperate zone. On the coast, the climate is monsoonal with warm, humid summers and cold winters.

In the subtropical zone on the plains, the air is positive all year round. The northern boundary of the belt is drawn along the January isotherm at 0°C. On the territory of Eurasia, three climatic regions are separated in this belt. - in the west of the belt. Dry tropical air masses dominate here in summer (it is cloudless and hot in summer), and in winter - sea air of temperate latitudes (it rains in winter). The region of the continental climate occupies the territory of the Near Asian Highlands (the Malay Peninsula, the Armenian and the north of the Iranian Highlands). Winters in this area are relatively cold (snowfalls and temperatures below 0°C are possible), summers are hot and very dry. The annual amount of precipitation is small, and they fall in the winter-spring period. The area of monsoon subtropical climate is in the east and occupies the southern half of the islands. Here, a characteristic is the summer maximum in their annual distribution.

The tropical belt does not form a continuous strip and is represented only in the southwest of Asia (the peninsula, the south of Mesopotamia and the Iranian Highlands, the northwestern regions of the Hindustan peninsula). Continental tropical air masses dominate here throughout the year. The amount of precipitation in the plains does not exceed 200 mm, and in belt regions - below 50 mm per year. Summer is very hot - the average temperature in July is from +30 to +35°C. In (Arabia) temperatures up to +55°C were observed. Average January temperatures are from +12° to +16°С.

The belt includes the Hindustan and Indochina peninsulas, the Indo-Gangetic plain, an island (without the southwestern part), Southeast China,. This belt is characterized by a seasonal change of air masses: in summer, humid equatorial air, brought by the monsoon, dominates; in winter - a relatively dry tropical trade wind of the northern hemisphere. The hottest time of the year is spring, when daytime temperatures can exceed +40°C.

It is located on the Malay Archipelago (excluding East Java and Small), the peninsula, the southwest of Sri Lanka and the south. Throughout the year, maritime equatorial air masses dominate here. They are formed from tropical air coming from the trade winds of both hemispheres. This climate is characterized by abundant rainfall (2000-4000 mm per year) and constantly high temperatures (above +25°C).