The air masses surrounding us are in continuous motion: up and down, horizontally. The horizontal movement of air is what we call wind. Wind currents are formed according to their own specific laws. To characterize them, indicators such as speed, strength and direction are used.

The winds of different climatic regions have their own features and characteristics. The temperate latitudes of the Northern and Southern Hemispheres are blown by westerly winds.

Constants and variables

Wind direction determines areas of high and low pressure. air masses moving from areas of high pressure to areas of low pressure. The direction of the wind also depends on the action of the earth's rotation: in the northern hemisphere, the flows are corrected to the right side, in the southern hemisphere - to the left. Air flows can be either constant or variable.

westerly winds temperate latitudes, trade winds, northeast and southeast belong to the group of constants. If the trade winds are called the winds of the tropics (30 o N - 30 o S), then westerly winds prevail in temperate latitudes from 30 o to 60 o in both hemispheres. In the Northern Hemisphere, these air currents deviate to the right.

In addition to constant winds, there are variable or seasonal winds - breezes and monsoons, as well as local winds that are typical only for a particular region.

The course of the West Winds

Air, moving in a certain direction, has the ability to carry huge masses of water in the ocean, creating strong currents - rivers among the oceans. Wind currents are called wind currents. In temperate latitudes, westerly winds and the rotation of the earth direct surface currents towards the western shores of the continents. In the northern hemisphere they move clockwise, in the southern hemisphere they move counterclockwise. In the Southern Hemisphere, the action of the wind and the earth's rotation have created a strong current of West Winds along the coasts of Antarctica. This is the most powerful ocean current that encircles the entire globe from west to east in the area between 40 o and 50 o south latitude. This current serves as a barrier separating the southern waters of the Atlantic, Indian and Pacific Oceans from the cold waters of the Antarctic.

wind and climate

Western winds have an impact on the climate of a large area of ​​the Eurasian continent, especially on that part of it that is located in temperate zone. With the breeze of the West, coolness comes to the continent in the midst of summer heat and thaw in winter. It is the winds from the west in cooperation with the warm ocean current that explain the fact that the climate of the north-west of Europe is much warmer than the same latitudes of North America. With advancement deep into the continent to the east, the influence of the Atlantic decreases, but the climate becomes completely continental only beyond the Ural Range.

In the Southern Hemisphere, violent winds from the west are not hindered by any obstacles in the form of continents and mountains, they are free and free: they storm, fight ships, rush east at high speed.

Who is friends with the wind

Indomitable news is especially familiar to sailors on the routes of the Cape of Good Hope - New Zealand- Cape Horn. Picking up a passing sailboat, they can accelerate it faster than a diesel ship. Sailors call western winds gallant in the Northern Hemisphere and roaring forties in the Southern.

Westerly winds also caused a lot of trouble to the first aviators. They were allowed to fly from America to Europe, as they were on the way. Pilots passed the route without problems. The situation with the flight from Europe to America was quite different. Of course, no wind is a hindrance to modern supersonic liners, but in the 20-30s of the nineteenth century it turned out to be a significant obstacle.

So the French pilots Nengesier and Colli in 1919 made a historic flight across the Atlantic Ocean on the route Newfoundland - Azores - Iceland. And here is the same path to reverse side ended tragically. The pilots intended to repeat the famous path of Columbus by air, only 34 years later the wreckage of their aircraft was discovered on the coast of the United States.

The tragedy is explained by the fact that strong winds significantly delayed the aircraft, and there was simply not enough fuel to reach the destination.

The Soviet pilots Gordienko and Kokkinaki were the first to defeat the oncoming waves in 1939, successfully overcoming the French route.

From the area where the pressure is increased, the air moves, "flows" to where it is lower. The movement of air is called wind. To observe the wind - its speed, direction and strength - use a weather vane and an anemometer. Based on the results of observations of the direction of the wind, wind rose(Fig. 37) for a month, season or year. Wind rose analysis allows you to establish the prevailing wind directions for a given area.

Rice. 37. Rose of Wind

Wind speed measured in meters per second. At calm wind speed does not exceed 0 m/s. Wind with a speed of more than 29 m/s is called hurricane. The strongest hurricanes were recorded in Antarctica, where wind speeds reached 100 m/s.

the strength of the wind measured in points, it depends on its speed and air density. On the Beaufort scale, a calm is 0, and a hurricane is a maximum of 12.

Knowing general patterns distribution of atmospheric pressure, it is possible to establish the direction of the main air flows in the lower layers of the Earth's atmosphere (Fig. 38).

Rice. 38. Scheme general circulation atmosphere

1. From tropical and subtropical areas of high pressure, the main flow of air rushes to the equator, to the area of ​​constant low pressure. Under the influence of the deflecting force of the Earth's rotation, these flows deviate to the right in the Northern Hemisphere and to the left in the Southern. These constantly blowing winds are called trade winds.

2. Part of the tropical air moves to temperate latitudes. This movement is especially active in summer, when lower pressure prevails there. These air currents in the Northern Hemisphere also deviate to the right and first take a southwestern and then a western direction, and in the Southern - a northwestern, turning into a western one. Thus, in the temperate latitudes of both hemispheres, western air transport.

3. From the polar regions of high pressure, air moves to temperate latitudes, taking a northeasterly direction in the Northern and southeasterly in the Southern Hemispheres.

The trade winds, westerly winds of temperate latitudes and winds from the polar regions are called planetary and distributed regionally.

4. This distribution is disturbed on the eastern coasts of the continents of the Northern Hemisphere in temperate latitudes. As a result of seasonal changes in pressure over land and the adjacent water surface of the ocean, winds blow here from land to sea in winter, and from sea to land in summer. These winds, which change their direction with the seasons, are called monsoons. Under the influence of the deflecting influence of the rotating Earth, the summer monsoons take a southeasterly direction, and the winter monsoons take a northwesterly direction. Monsoon winds are especially characteristic of Far East and East China, to a lesser extent they appear on the east coast of North America.

5. In addition to planetary winds and monsoons, there are local, so called local winds. They arise due to the features of the relief, uneven heating of the underlying surface.

breezes- coastal winds observed in clear weather on the shores of water bodies: oceans, seas, large lakes, reservoirs and even rivers. During the day they blow from the water surface (sea breeze), at night - from land (coastal breeze). During the day, the land heats up more than the sea. The air above the land rises, the currents of air from the sea rush to its place, forming a daytime breeze. In tropical latitudes, daytime breezes are fairly strong winds that bring moisture and coolness from the sea.

At night, the surface of the water is heated more than the land. The air rises, and in its place air rushes from the land. A night breeze forms. In terms of strength, it is usually inferior to daytime.

In the mountains there are hair dryers- warm and dry winds blowing on the slopes.

If low mountains rise like a dam in the path of moving cold air, there may be boron. Cold air, having overcome a low barrier, falls down with great force, and at the same time there is a sharp drop in temperature. Bora is known under different names: in Lake Baikal it is sarma, in North America it is chinook, in France it is mistral, etc. In Russia, boron reaches its special strength in Novorossiysk.

dry winds are dry and sultry winds. They are typical for arid regions of the globe. In Central Asia, dry wind is called simum, in Algeria - sirocco, in Egypt - hatsin, etc. The speed of the dry wind reaches 20 m / s, and the air temperature is 40 ° C. Relative humidity during a dry wind drops sharply and drops to 10%. Plants, evaporating moisture, dry up on the vine. In deserts, dry winds are often accompanied by dust storms.

The direction and strength of the wind must be taken into account during construction settlements, industrial enterprises, dwellings. Wind is one of the most important sources of alternative energy, it is used to generate electricity, as well as to operate mills, water pumps, etc.

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§ 35. Atmospheric pressure§ 37. Weather and its forecasting

SECTION 3 GEOGRAPHICAL SHELL

Topic 2. Atmosphere

§ 36. Wind. Constant and variable winds

Remember

How do you watch the wind?

What direction of wind prevails in your area?

Wind - the movement of air in a horizontal or close to it direction. In this case, air moves from an area of ​​high atmospheric pressure to an area of ​​low atmospheric pressure. The wind is characterized by speed, strength and direction. Wind speed is measured in meters per second (m/s) or kilometers per hour (km/h). To convert meters per second to kilometers per hour, you need to multiply the speed in meters per second by 3.6.

The strength of the wind is determined by the pressure of moving air on objects. It is measured in kilograms per square meter (kg/m2). The strength of the wind depends on its speed. Thus, a wind with a speed of 100 km/h has a force 10 times greater than with a speed of 10 km/h. The greater the difference in atmospheric pressure, the stronger and faster the wind blows. The absence of any sign of wind is called calm.

Facts of the present

Strongest winds. The "pole of winds" on Earth is considered to be the outlying parts of Antarctica, where the winds blow 340 days a year. The highest wind speed - 371 km / h - was registered in 1934 in the USA, on a mountain in the state of New Hampshire. In Ukraine, the strongest wind was on Ai-Petri in the Crimea (its speed reached 180 km/h).

The direction of the wind is determined by the position of the side of the horizon from which it blows. To indicate the direction of the wind in practice, the horizon is divided into eight directions. Of these, four head ones - north (Mon), south (S), east (Nx) and west (W) and four intermediate ones - northeast (North-East), northwest (North-West), southeast ( Pd-Sx) and southwestern (Pd-Zx).

For example, when the wind blows from an area located between south and east, it is called southeasterly (Pd-Sh). The direction and speed of the wind is determined using a weather vane (Fig. 97). A visual representation of the directions of the winds that prevail in a given area is given by a special diagram - the wind rose (Fig. 98). This graphic image frequency of wind directions. The length of its rays is proportional to the frequency of winds of a given direction.

Rice. 97. Weather vane

PRACTICAL WORK № 8(continuation)

Observing the weather: compiling a wind rose

According to the data in the table, build a wind rose. To do this, first draw the coordinates, indicating four wind directions and four intermediate ones. On the scale of your choice, set aside the number of segments corresponding to each direction. Connect the ends of the segments in series with each other. Paint over the resulting wind rose and indicate which direction of the wind prevailed. In figure 98, notice how the winds of different directions are indicated.

Rice. 98. Wind rose

Direction of the wind
Wind repeatability, %

Constant and variable winds. There is not a single windless place on the globe. There are many various types winds. There are winds that blow constantly, and there are those that change their direction during the day or year. Constant winds- trade winds - occur between the high tropical and equatorial low atmospheric pressure belts in the Northern and Southern hemispheres of the Earth (Fig. 99). Due to the rotation of the globe, the trade winds in the Northern Hemisphere move from the northeast to the southwest, and in the Southern - from the southeast to the northwest. The trade winds hardly change their direction throughout the year. their speed averages 5-6 m/s, and the vertical thickness reaches 2-4 km and increases towards the equator.

Western winds blow in temperate latitudes. They are also permanent.

Rice. 99. Formations of the trade winds

Rice. 100. Formations of day (a) and night (b) breeze

There are much more variable winds on the globe than constant ones. Distributed only in certain areas, they are called local.

Local winds blow over a relatively small area (from hundreds of meters to tens of kilometers) and significantly affect the weather in the area. An example of a local wind is a breeze. Translated from French, this word means "light breeze." Its speed is really insignificant - up to 4 m / s. The breeze blows with a daily frequency on the coast of the seas, large lakes and some major rivers. This wind changes its direction twice a day, which is caused by uneven heating of the land surface and the reservoir. The daytime, or sea, breeze moves from the water surface to the land, and the night, or coastal, breeze moves from the chilled land coast to the reservoir (Fig. 100).

The breeze occurs predominantly in summer, when the temperature difference between land and water reaches highest values. In Ukraine, breezes are observed on the coast of reservoirs, the Black and Azov Seas.

Amazing Phenomena

Wind from the mountains.

Interesting local winds are fioni, which do not have a certain periodicity. They are not permanent and last on average from one to two days.

Fion is a strong, gusty, dry and warm wind that blows from the mountain peaks into the valleys. It occurs when air passes over the ridge mountain range and, descending under the slope, quickly heats up (Fig. 101). In this case, the temperature can reach maximum values ​​for this time of year. So, with a strong fion on the icy island of Greenland, the temperature rises by 20-25 ° C. Fjon causes snowmelt in the mountains in winter, and droughts and fires in summer. In the mountainous regions of Ukraine, fyons that blow from the southeastern slopes of the Crimean Mountains near Alushta can suddenly raise the temperature here to 28 ° C. Fioni in the Ukrainian Carpathians have a speed of up to 25 m/s.

Rice. 101. Formation of fiefs

Rice. 102. Movement of the monsoons

The monsoons are also included in the winds that change their direction. The word "monsoon" is translated from Arabic as "season". This name is not accidental, because the monsoon changes its direction twice a year: in winter it blows from land to ocean, and in summer, on the contrary, from ocean to land (Fig. 102). (Consider why the monsoon changes its direction with the seasons.) Monsoon winds are best expressed in the south and east of Asia, the northern Indian Ocean, and the western Pacific Ocean. The Asian summer monsoon is especially powerful. He contains a large number of moisture and heat, it is associated with heavy rainfall.

The wind is horizontal movement air, resulting from the difference in atmospheric pressure.

The wind is characterized by speed, strength and direction.

Constant winds blow constantly, variable winds change their direction during the day or year.

Questions and tasks for self-examination

Build a wind rose based on your observations. Explain which wind direction prevails in your area. Draw schematically the direction of the wind according to the following data: a) the pressure at point A is 760 mm Hg. Art., and in point B - 784 mm Hg. Art.; b) on the coast, the pressure is 758 mm Hg. Art., and over the lake - 752 mm Hg. Art. When will the wind be stronger?

Choose from the listed winds the one that almost does not change its direction: a) trade wind; b) monsoon c) breeze.

What is the cause of wind? What determines the strength and speed of the wind?

Wind- the movement of air is usually in a horizontal direction relative to earth's surface. Air moves out. The reason for the occurrence of wind is the uneven heating of various parts of the Earth. Over the vast territories of our planet, systems of constant and variable winds - air currents - are formed.

Constant winds (air currents):

trade winds. They blow from the tropics of the Northern and Southern Hemispheres, where areas of high pressure are formed, located in areas of low pressure. As a result of the rotation of the Earth around its axis, these winds are deflected: in the Northern Hemisphere they blow from the northeast to the southwest, in the Southern - from the southeast to the northwest. eastern coast, Africa, is located all year round under the influence of the trade winds, which originate over the oceans and bring throughout the year. The north is under the influence of the trade winds, which originate at 30 ° latitudes of the Northern Hemisphere in the center of Asia. These winds do not bring precipitation: they come dry and hot. The influence of these winds can explain the location in the big world - .

westerly winds. These are the winds that prevail in the troposphere and stratosphere of the middle latitudes of the Earth. They blow from the tropics of the North and southern hemisphere, where an area of ​​high pressure is formed, towards 60° latitudes, where areas of low pressure are formed. Due to the rotation of the Earth, they constantly deviate to the east (in the Northern Hemisphere to the right, in the Southern Hemisphere - to the left) and create an air flow from west to east.

There are also winds of local circulation:

Breeze(French brise - light wind). This is a local wind of low speed, changing its direction twice a day. It occurs on the shores of the seas, lakes. During the day, land heats up faster than water. An area of ​​low pressure is established over land, and a high pressure area is established over water, and the daytime breeze blows from the sea or lake on the coast. At night the picture changes. Land cools faster than water, and the night breeze blows from the chilled coast, over which a high pressure area is established, to the warm one.

During the era of sailing, the breezes were used to start sailing.

Bora(Italian bora; Greek boreas - North wind). This is a strong, gusty wind blowing from the coastal mountains towards the sea, mainly in the cold season. Bora occurs when cold air over land is separated from warm air over water by a low ridge. Cold air gradually accumulates in front of the ridge and then rolls down to the sea at high speed, so the temperature on the coast drops sharply. Coastal bora is especially typical. The bora leads to icing of coastal buildings, to the capsizing of ships.

A variation of bora is the sarma wind, the name of which comes from the name of the river that flows into. It is swooping in suddenly and rising steep on the lake. Occurs when transshipment through the ridges of mountains. When this wind approaches, meteorologists broadcast a storm warning.

Fen. It is a warm and dry gusty wind from the mountains. It blows frequently in winter and spring and causes rapid snowmelt. Foehn is very common in the mountains of Central Asia,.

Simoom(arab.) - a sultry wind in the deserts and North Africa, carrying hot sand and dust. This wind occurs when the Earth warms up strongly in

Education local winds associated with the nature of the underlying surface (orography, type of surface - water or land) and temperature. Breezes are local winds of thermal origin. They are better expressed in cloudless anticyclonic weather and are especially often manifested on the western coasts of the tropics, where heated continents are washed by the waters of cold currents. We grouped other local winds depending on their properties and origin (temperature or type of landscape over which they form) into three groups: cold, mountain-valley and desert. Separately, the local names of the Baikal winds were given.

local winds	Description of the wind
Cold local winds:
Blizzard	cold piercing wind of storm force in Canada and Alaska (similar to snowstorm in Siberia).
Bora (Greek "boreas" - north wind)	strong, gusty wind blowing mainly in winter months from mountain ranges on the coast of the seas. Occurs when a cold wind (high pressure) crosses the ridge and displaces the warm and less dense air (low pressure) on the other side. In winter it causes severe cooling. It occurs in the northwest of the Adriatic Sea. Black Sea (near Novorossiysk), on Baikal. Wind speed during bora can reach 60 m/s, its duration is several days, sometimes up to a week.
	dry, cold, northerly or northeasterly wind in mountainous regions of France and Switzerland
Borasco, burraska (Spanish "borasco" - small bora)	a strong squall with a thunderstorm over the Mediterranean Sea.
	small intense whirlwind in Antarctica.
	cold north wind in Spain.
	cold wind from Siberia, bringing sharp cold snaps, frosts and snowstorms, in Kazakhstan and the deserts of Central Asia.
	sea ​​breeze softening the heat on the northern coast of Africa.
	cold northeast wind blowing over the lower part of the Danube lowland.
Levantine	eastern strong, humid wind, accompanied by cloudy weather and rain in the cold half of the year over the Black and Mediterranean Seas.
	cold north wind over the coast of China.
Mistral	intrusion of a cold strong and dry wind from the polar regions of Europe along the valley of the Rhone River to the coast of the Gulf of Lion in France from Montpellier to Toulon in the winter-spring period (February, March).
Meltemi	northern summer wind in the Aegean.
	cold north wind in Japan, blowing from the polar regions of Asia.
	bora-type wind only in the region of Baku (Azerbaijan).
Northser, norter (eng. "norther" - north)	strong cold and dry winter (November - April) north wind blowing from Canada to the USA, Mexico, the Gulf of Mexico, up to the northern part South America. Accompanied by rapid cooling, often with showers, snowfalls, ice.
	cold south storm wind in Argentina. Accompanied by rain and thunderstorms. Then the cooling rate reaches 30 ° C per day, Atmosphere pressure increases sharply, the cloudiness dissipates.
	strong winter wind in Siberia, lifting snow from the surface, resulting in reduced visibility to 2-5 m.
Mountain-valley winds: foehns (bornan, breva, talvind, helm, chinook, garmsil) - warm, dry, gusty winds that cross the ridges and blow from the mountains down the slope into the valley last less than a day. Foehn winds have their own local names in different mountain regions.
	breeze in the Swiss Alps, blowing from the valley of the river. Drance to the middle part of Lake Geneva.
	afternoon valley wind, combined with a breeze on Lake Como (Northern Italy).
Garmsil	strong dry and very hot (up to 43 ° C and above) wind on the northern slopes of the Kopetdag and the lower parts of the Western Tien Shan.
	pleasant valley wind in Germany.
Chinook (or Chinook)	dry and warm southwest wind on the eastern slopes of the Rocky Mountains of North America, which can cause very large temperature fluctuations, especially in winter. There is a case when in January in less than a day the air temperature increased by 50°: from -31° to + 19°. Therefore, the Chinook is called the "snow eater" or "snow eater".
Desert winds: samum, sirocco, khamsin, habub - dry, very hot dusty or sandy winds.
	dry hot western or southwestern wind in the deserts of the North. Africa and Arabia, swoops in like a whirlwind, closes the Sun and the sky, rages for 15-20 minutes.
	dry, hot, strong southerly wind blowing to the Mediterranean countries (France, Italy, the Balkans) from the deserts of North Africa and Arabia; lasts several hours, sometimes days.
	sweltering hot and dusty wind blowing over Gibraltar and southeast Spain,
	it is a wind with high temperature and low air humidity in the steppes, semi-deserts and deserts, it is formed along the edges of anticyclones and lasts for several days, increasing evaporation, drying up the soil and plants. It prevails in the steppe regions of Russia, Ukraine, Kazakhstan and the Caspian region.
	dust or sandstorm in northeast Africa and the Arabian Peninsula.
Khamsin (or "fifty days")	hot gale in Egypt blowing from Arabia for up to 50 consecutive days.
Harmattan	local name for the northeast trade wind blowing from the Sahara to the Gulf of Guinea; brings dust, high temperatures and low humidity.
	analogue of khamsin in Central Africa.
Eblis ("dust devil")	a sudden rise of heated air on a calm day in the form of a whirlwind that carries sand and other objects (plants, small animals) to a very high altitude.
Other local winds:
	dusty southern or southwestern wind blowing from Afghanistan along the valleys of the Amu Darya, Syr Darya, Vakhsh. It inhibits vegetation, fills the fields with sand and dust, and demolishes the fertile soil layer. In early spring, it is accompanied by showers and cold snaps to frost, destroying cotton seedlings. In winter, it is sometimes accompanied by sleet and leads to frostbite and death of livestock caught on the plains.
	strong wind from the Caspian, bringing surge floods to the lower reaches of the Volga.
	southeast trade wind in the Pacific Ocean (for example, off the islands of Tonga).
Cordonaso	strong south winds along the western coast of Mexico.
	sea ​​breeze blowing from Pacific Ocean on the coast of Chile, especially strong in the afternoon in the city of Valparaiso, which is why port operations are even suspended. Its antipode - a coastal breeze - is called a terrap.
Probe (sondo)	strong northern or western dry and hot foehn-type wind on the eastern slopes of the Andes (Argentina). It has a depressing effect on people.
	predominant in the eastern part mediterranean sea, warm, brings rain and storms (lighter in the western Mediterranean)
	fair wind on rivers and lakes.
Tornado (Spanish: Tornado)	a very strong atmospheric vortex over land in North America, characterized by high frequency, is formed as a result of the collision of cold masses from the Arctic and warm masses from the Caribbean.
Winds of Baikal:
Verkhovik, or hangar	north wind overpowering other winds.
Barguzin	northeast storm wind blowing in the central part of the lake from the Barguzin valley across and along Baikal
	local southwest storm wind bringing overcast weather.
Harahaiha	autumn-winter northwest wind.
	southeast storm wind blowing from the valley of the river. Goloustnoy.
	cold strong chilling winter wind blowing along the river valley. Sarma.

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A source of information: Romashova T.V. Geography in figures and facts: Educational manual / - Tomsk: 2008.