The horizontal movement of air above the Earth's surface is called wind. The wind always blows from an area of ​​high pressure to an area of ​​low pressure.

Wind characterized by speed, strength and direction.

Wind speed and strength

Wind speed measured in meters per second or points (one point is approximately equal to 2 m/s). The speed depends on the baric gradient: the greater the baric gradient, the higher the wind speed.

The force of the wind depends on the speed (Table 1). The greater the difference between adjacent areas of the earth's surface, the stronger the wind.

Table 1. Wind strength near the earth's surface on the Beaufort scale (at a standard height of 10 m above an open flat surface)

Beaufort points	Verbal definition of wind strength	Wind speed, m/s	wind action
			Calm. Smoke rises vertically	Mirror-smooth sea
			The direction of the wind is noticeable but the smoke is carried, but not by the weather vane	Ripples, no foam on the ridges
			The movement of the wind is felt on the face, the leaves rustle, the weather vane is set in motion	Short waves, crests do not tip over and appear glassy

			Leaves and thin branches of trees are constantly swaying, the wind is waving the top flags	Short, well defined waves. Combs, tipping over, form a vitreous foam, occasionally small white lambs are formed
	Moderate		The wind raises dust and pieces of paper, sets in motion the thin branches of trees.	The waves are elongated, white lambs are visible in many places
			Thin tree trunks sway, waves with crests appear on the water	Well developed in length, but not very large waves, white lambs are visible everywhere (splashes form in some cases)
			Thick tree branches sway, telegraph wires hum	Large waves begin to form. White foamy ridges take up significant space (probable splashing)
			Tree trunks sway, it's hard to go against the wind	Waves pile up, crests break, foam falls in stripes in the wind
	Very strong		The wind breaks the branches of trees, it is very difficult to go against the wind	Moderately high long waves. On the edges of the ridges, spray begins to take off. Stripes of foam lie in rows in the direction of the wind
			Minor damage; the wind rips off the smoke caps and roof tiles	high waves. Foam in wide dense stripes lays down in the wind. The crests of the waves begin to capsize and crumble into spray that impair visibility.

	Heavy storm		Significant destruction of buildings, trees uprooted. Rarely on land	Very high waves with long downward curved crests. The resulting foam is blown by the wind in large flakes in the form of thick white stripes. The surface of the sea is white with foam. The strong roar of the waves is like blows. Visibility is poor
	Violent storm		Large destruction over a large area. Very rare on land	Exceptionally high waves. Small to medium sized boats are sometimes out of sight. The sea is all covered with long white flakes of foam, spreading downwind. The edges of the waves are everywhere blown into foam. Visibility is poor
		32.7 and more		The air is filled with foam and spray. The sea is all covered with strips of foam. Very poor visibility

Beaufort scale- a conditional scale for visual assessment of the strength (speed) of the wind in points according to its effect on ground objects or on waves at sea. It was developed by the English admiral F. Beaufort in 1806 and at first was used only by him. In 1874, the Standing Committee of the First Meteorological Congress adopted the Beaufort scale for use in International synoptic practice. In subsequent years, the scale has changed and refined. The Beaufort scale is widely used in marine navigation.

Direction of the wind

Direction of the wind is determined by the side of the horizon from which it blows, for example, the wind blowing from the south is south. The direction of the wind depends on the pressure distribution and on the deflecting effect of the Earth's rotation.

On the climate map, the prevailing winds are shown by arrows (Fig. 1). The winds observed near the earth's surface are very diverse.

You already know that the surface of land and water heats up in different ways. On a summer day, the land surface heats up more. From heating, the air above the land expands and becomes lighter. Over the pond at this time the air is colder and therefore heavier. If the reservoir is relatively large, on a quiet hot summer day on the shore you can feel a light breeze blowing from the water, above which it is higher than above land. Such a light breeze is called daytime. breeze(from the French brise - light wind) (Fig. 2, a). The night breeze (Fig. 2, b), on the contrary, blows from the land, since the water cools much more slowly and the air above it is warmer. Breezes can also occur at the edge of the forest. The scheme of breezes is shown in fig. 3.

Rice. 1. Distribution scheme prevailing winds on the globe

Local winds can occur not only on the coast, but also in the mountains.

Föhn- a warm and dry wind blowing from the mountains to the valley.

Bora- gusty, cold and strong wind that appears when cold air rolls over low ridges to the warm sea.

Monsoon

If the breeze changes direction twice a day - day and night, then seasonal winds - monsoons— change their direction twice a year (Fig. 4). In summer, the land warms up quickly, and the air pressure over its surface hits. At this time, cooler air begins to move to land. In winter, the opposite is true, so the monsoon blows from land to sea. With the change of the winter monsoon to the summer monsoon, dry, slightly cloudy weather changes to rainy.

The action of monsoons is strongly manifested in the eastern parts of the continents, where they are adjacent to vast expanses of oceans, so such winds often bring heavy rainfall to the continents.

The unequal nature of the circulation of the atmosphere in different regions of the globe determines the differences in the causes and nature of the monsoons. As a result, extratropical and tropical monsoons are distinguished.

Rice. 2. Breeze: a - daytime; b - night

Rice. Fig. 3. Scheme of breezes: a - in the afternoon; b - at night

Rice. 4. Monsoons: a - in summer; b - in winter

extratropical monsoons - monsoons of temperate and polar latitudes. They are formed as a result of seasonal fluctuations in pressure over the sea and land. The most typical area of ​​their distribution is Far East, Northeast China, Korea, to a lesser extent - Japan and the northeast coast of Eurasia.

tropical monsoons - monsoons of tropical latitudes. They are due to seasonal differences in the heating and cooling of the Northern and Southern hemispheres. As a result, pressure zones shift seasonally relative to the equator to the hemisphere in which given time summer. Tropical monsoons are most typical and persistent in the northern part of the Indian Ocean basin. This is largely facilitated by the seasonal change of regime. atmospheric pressure over the Asian continent. The fundamental features of the climate of this region are associated with the South Asian monsoons.

The formation of tropical monsoons in other regions of the globe is less characteristic when one of them, the winter or summer monsoon, is more clearly expressed. Such monsoons are observed in Tropical Africa, in northern Australia and in the equatorial regions of South America.

Earth's constant winds - trade winds And westerly winds - depend on the position of atmospheric pressure belts. Since low pressure prevails in the equatorial belt, and near 30 ° N. sh. and yu. sh. - high, near the surface of the Earth throughout the year the winds blow from the thirtieth latitudes to the equator. These are trade winds. Under the influence of the rotation of the Earth around its axis, the trade winds deviate to the west in the Northern Hemisphere and blow from the northeast to the southwest, and in the Southern they are directed from the southeast to the northwest.

From the high pressure belts (25-30°N and S), the winds blow not only towards the equator, but also towards the poles, since at 65°N. sh. and yu. sh. low pressure prevails. However, due to the rotation of the Earth, they gradually deviate to the east and create air currents moving from west to east. Therefore, in temperate latitudes ah prevailing westerly winds.

Wind is a horizontal and evenly moving air flow relative to the earth's surface. There is a huge variety of local winds, which cannot be explained by the example of ordinary observations due to their inherent specific features that are characteristic of a particular region. So, to talk about what kind of winds there are on the coast, for example, such observations allow: at noon a breeze blows from the sea - cool, gentle, and at night the same wind moves from land towards the sea. In deserts and mountainous areas, mainly mountain or valley winds "live". However, there are types of winds that apply to the entire planet as a whole.

What are the winds

1. Monsoon is a wind with a periodic character, and carrying a lot of moisture. In winter, the monsoon blows from the land to the ocean, and in the summer, from the ocean to land. Basically, monsoons prevail in the tropical zone and are essentially seasonal winds, lasting several months each year.
2. The trade winds are winds with a constant character, moving with a fairly stable force of three or four points. The trade winds move in almost the same direction, sometimes slightly deviating. Such dynamics of movement leads to mixing air masses planets, up to global scales: for example, the trade winds blowing over the Atlantic Ocean can carry dust particles from the African deserts to the territory of the West Indies and several North American regions.
3. Local winds:
   • Breeze - a warm breeze blowing from the coast to the sea at night (coastal breeze) and in the opposite direction during the day (sea breeze). The main generators of predominant winds in coastal areas are sea and continental breezes. Due to the fact that the sea (reservoir) warms up more slowly than land due to the greater heat capacity of water, the air heated above the land rises more strongly, forming a zone of low pressure. Thus, a difference in atmospheric pressure is formed between air currents and a cool sea breeze is born on the coast.

     At night, due to the lower heat capacity, the land cools faster, and the sea breeze stops. At the moment when the temperature of the land is below the temperature on the surface of the reservoir, a reverse pressure drop is formed, which creates (if there is no strong wind from the sea) a continental breeze moving from the land towards the sea.

   • Bora is a wind with a cold, sharp character, moving from the side of the mountains to the territory of the coast or valley.
   • Foehn is a dry, strong and warm wind that moves from the mountains to the territory of the valley or the coast.
   • Sirocco - name on Italian southwestern or strong south wind formed in the Sahara desert.
4. Variable and constant winds.

   The nature of the movement of air masses also helps to understand what kind of winds there are. So, variable winds are able to change their direction. These include the breezes already discussed above (translated from French "Breeze" means light wind), since they change the direction of their movement twice a day (day and night).

   Monsoons are born in the same way as breezes. They change the direction of their movement twice a year seasonally (summer and winter). The Arabic name for the wind is "monsoon" which means "season". When the summer monsoon forms, there are thunderstorms due to the strong saturation of the air with sea water, and in winter dry and cold air moves from the land.

5. Also, the winds can be described as gusty and light, or give them a name based on the direction of their movement, for example: east, southwest, etc.

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 North and southern hemispheres 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). (Think about why the monsoon changes its direction with the seasons.) Monsoon winds are best expressed in the south and east of Asia, in the north of the Indian and in the west Pacific Oceans. 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?

Atmospheric pressure and its measurements

The air surrounding the Earth has mass, and therefore presses on the earth's surface. 1 liter of air at sea level weighs about 1.3 g. Therefore, the atmosphere presses on every square centimeter of the earth's surface with a force of 1.33 kg. This average air pressure at sea level, corresponding to the mass of a mercury column 760 mm high with a cross section of 1 cm2, is taken as normal. Air pressure is also measured in millibars: 1 mm of pressure is 1.33 mbar. So, to convert millimeters to millibars, you need to multiply millimeters of pressure by 1.33.

The pressure value varies with air temperature and altitude. Since air expands when heated and contracts when cooled, warm air is lighter (causes less pressure) than cold air. As air rises upward, the pressure decreases mainly because the height of its column is less per unit area. Therefore, in high mountains, the pressure is much less than at sea level. The vertical segment through which the atmospheric pressure decreases by one is called the baric degree. In the lower layers of the atmosphere near the surface, the pressure decreases by about 10 mm for every 100 m of elevation.

A mercury barometer is used to measure pressure, and in field conditions- metal aneroid barometer. The latter is a metal box from which air is pumped out. When atmospheric pressure increases, the bottom of the box contracts, and when it decreases, it unbends. These changes are transmitted to the arrow, which moves along the dial.

Winds and their origin

Zonality also appears in the distribution of pressure on the earth's surface. The general planetary scheme of pressure distribution is as follows: a belt of low pressure extends along the equator; to the north and south of it at the C-40 latitudes - high pressure belts, further to 60-70 ° N. and yu. sh. - Belts of low pressure, in the polar regions - areas of high pressure. Real distribution pattern

pressure is much more complicated, which is reflected in the maps of July and January isobars).

The uneven distribution of pressure on the globe causes the movement of air from an area of ​​high pressure to an area of ​​low pressure. This movement of air in a horizontal direction is called wind. The greater the pressure difference, the stronger the wind blows. The strength of the wind is estimated from 0 to 12 points.

The direction of the wind is determined by the side of the horizon from which it blows. The wind changes with changes in pressure. The rotation of the Earth around its axis also has a significant influence on its direction.

General circulation of the atmosphere. Trade winds and other constant winds

The winds observed above the earth's surface are divided into three groups: local winds caused by local conditions (temperature, relief features) winds of cyclones and anticyclones; winds, is part of the general circulation of the atmosphere. General circulation atmospheres form the largest air currents on a planetary scale, covering the entire troposphere and lower stratosphere (up to about 20 km) and are characterized by relative stability. In the troposphere, these include the trade winds, westerly winds of temperate latitudes and easterly winds of the subpolar regions, and monsoons. The cause of these planetary air movements is pressure difference.

A belt of low pressure forms above the equator due to the fact that here the air is warm during the year and it mainly rises (upward air movement dominates). In the upper layers of the troposphere, it cools and spreads towards high latitudes. The Coriolis force, deflecting air currents coming in the upper troposphere from the equator, provides them with a westerly direction at 30 latitudes, forcing them to move only along the parallels. Therefore, this cooled air is subjected here to a downward movement, causing high pressure (although the air temperature near the surface is even higher than at the equator). These subtropical high-pressure belts serve as the main "vitrorozdilams" on Earth. From them, the air volumes of the lower troposphere are directed both towards the equator and towards temperate latitudes.

Winds, characterized by stability of direction and speed, throughout the year blow from high pressure belts (25-35 ° N and S) to the equator are called trade winds. Due to the rotation of the Earth around its axis, they deviate from the previous direction, in the Northern Hemisphere they blow from the northeast to the southwest, and in the Southern - from the southeast to the northwest.

Winds blowing from subtropical high pressure belts towards the poles, deviating to the right or left depending on the hemisphere, change their direction to the west. Therefore, in temperate latitudes, westerly winds predominate, although they have not become as strong as the trade winds.

Constant winds also blow from the high pressure regions of the polar latitudes towards the temperate latitudes with relatively low pressure. Experiencing the action of the force of rotation, in the Northern Hemisphere they are northeast, and in the South - southeast.

In temperate latitudes, where warm air masses meet from the tropics and cold air masses from the polar regions, frontal cyclones and anticyclones constantly arise, in which air is transported from west to east.

CONSTANT WIND - a wind that retains its direction and speed over time if its direction changes by no more than one rhumb within two minutes. There are winds of different constancy: in terms of speed - even, gusty (spirits), squally (bare); in direction - constant (trade wind, strip,) or unstable, changing, transitional (changeable, shaky) and vortex, circular (vortex,).

Dictionary of winds. - Leningrad: Gidrometeoizdat. L.Z. Proh . 1983

See what "STANDING WIND" is in other dictionaries:

WIND- WIND, wind man. movement, flow, flow, current, air flow. According to its strength, the wind happens: a hurricane, a kavk. bora: storm, storm (usually a thunderstorm and rain are connected with a storm), severe, strong, windstorms: medium, weak, calm wind or breeze, breeze, ... ... Dahl's Explanatory Dictionary

WIND- (Wind) movement of air masses in a horizontal direction, or, in other words, horizontal air currents. Each V. is characterized by two elements: the direction in which the air moves, and the speed with which it ... ... Marine Dictionary

A constant wind blowing without interruption for several days and nights on the lake. Seliger. Wed Married wind ... Dictionary of winds

sunny wind- This term has other meanings, see Solar wind (film) ... Wikipedia

SUNNY WIND- constant radial flow of solar plasma. corona into interplanetary right. The flow of energy coming from the bowels of the Sun heats the plasma of the corona up to 1.5 2 million K. Post. heating is not balanced by the loss of energy due to radiation, because the density of the corona is low. ... ... Physical Encyclopedia

sunny wind- represents a constant radial outflow of the plasma of the solar corona (See Solar corona) into interplanetary space. S.'s education associated with the flow of energy entering the corona from the deeper layers of the Sun. Apparently…… Great Soviet Encyclopedia

Conditional (calculated, fictitious) wind, constant along the entire trajectory of a flying projectile, rocket or other object. It has the same effect on flight as the actual wind (changing along the path). B. c. simplifies calculations of wind action ... Dictionary of Winds

STAND UP- where, to stand sometimes, at times, often. We stand at the gate, look at the passers-by. Stay and wait. Stand, stand for several times in different meanings. I stood at matins, and my legs ached. The ship lay at anchor and left. The regiment stood at ... ... Dahl's Explanatory Dictionary

Sea currents*- The forward movement of waters in the oceans and seas is called a current. Currents are subdivided, in 1 x, into constant, periodic and random, or irregular; in 2 x, on surface and underwater and, in 3 x, on warm and cold. Constant currents are not ... ...

sea ​​currents - … Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

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