Westerly winds. The course of the Westerly winds, their influence on the climate. The trade winds are sustainable winds Table constant winds
The movement of air above the Earth’s surface in the horizontal direction is called by the wind. Wind always blows from high pressure to low.
Wind characterized by speed, strength and direction.
Wind speed and strength
Wind speed measured in meters per second or in points (one point is approximately 2 m / s). The speed depends on the baric gradient: the larger the baric gradient, the higher the wind speed.
Wind speed depends on the speed (Table 1). The greater the difference between adjacent parts of the earth's surface, the stronger the wind.
Table 1. Wind power at the earth's surface according to the Beaufort scale (at a standard height of 10 m above an open, flat surface)|
Beaufort Points |
Verbal definition of wind power |
Wind speed, m / s |
Wind action |
|
|
Calm. Smoke rises vertically |
Mirror-smooth sea |
|||
|
The direction of the wind is noticeable but I relate the smoke, but not the weather vane |
Ripples, no crests on the crests |
|||
|
The movement of the wind is felt on the face, the leaves rustle, the vane is set in motion |
Short waves, crests do not tip over and appear glassy |
|||
|
Leaves and thin branches of trees sway all the time, the wind blows the top flags |
Short, well-defined waves. The rollers, overturning, form a glassy foam, sometimes small white lambs are formed |
|||
|
Moderate |
The wind picks up dust and paper, sets in motion the thin branches of trees |
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 (in some cases splashes form) |
|||
|
Thick branches of trees sway, telegraph wires buzz |
Large waves begin to form. White foamy crests occupy significant ploschas (splashes likely) |
|||
|
Tree trunks swing, it is difficult to go against the wind |
The waves are piled, the crests are breaking, the foam lays 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. At the edges of the ridges, splashes begin to take off. Strips of foam lie in rows in the direction of the wind. |
||
|
Minor damage; the wind tears off smoke caps and roof tiles |
High waves. Foam with wide dense strips lies downwind. The crests of the waves begin to tip over and crumble into splashes that impair visibility. |
|
Heavy storm |
Significant destruction of buildings, trees are uprooted. Rarely on land |
Very high waves with long curving downward ridges. 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 from foam. A strong rumble of waves is like blows. Visibility is poor |
||
|
Fierce storm |
Great destruction in a considerable space. On land is very rare |
Exceptionally high waves. Small and medium sized vessels are sometimes hidden from view. The sea is all covered with long white flakes of foam, located in the wind. The edges of the waves everywhere are blown away into foam. Visibility is poor |
||
|
32.7 and more |
The air is filled with foam and spray. The sea is all covered with stripes of foam. Very poor visibility |
Beaufort Scale - a conditional scale for a visual assessment of the strength (speed) of the wind in points by its effect on ground objects or by sea waves. It was developed by the English admiral F. Beaufort in 1806 and was first used only by himself. 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 changed and refined. Beaufort scale is widely used in marine navigation.
Direction of the wind
Direction of the wind determined by the side of the horizon from which it blows, for example, the wind blowing from the south is the south. The direction of the wind depends on the pressure distribution and on the deflecting action of the Earth's rotation.
On the climate map, prevailing winds are indicated by arrows (Fig. 1). Winds observed on the earth's surface are very diverse.
You already know that the surface of land and water heats up differently. On a summer day, the land surface heats up more. From heating, air over land expands and becomes lighter. Above the reservoir at this time, the air is colder and therefore heavier. If the pond is relatively large, on a quiet, hot summer day on the shore you can feel a slight breeze blowing from the water, above which is higher than over land. Such a light breeze is called daylight. a breeze (from the French. brise - light wind) (Fig. 2, a). The night breeze (Fig. 2, b), on the contrary, blows from land, as the water cools much more slowly and the air above it is warmer. Breezes can occur at the edge of the forest. The scheme of breezes is presented in fig. 3.
Fig. 1. The distribution pattern of the prevailing winds on the globe
Local winds can occur not only on the coast, but also in the mountains.
Foehn - warm and dry wind blowing from the mountains into the valley.
Bora - gusty, cold and strong winds that appear when cold air passes through 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 exerts air pressure over its surface. At this time, cooler air begins to move to land. In winter, it's the other way around, so the monsoon blows from land to sea. With the change of winter monsoon to summer, dry, low-cloudy weather changes to rainy.
The monsoon effect is strongly manifested in the eastern parts of the continents, where vast expanses of oceans are adjacent to them, so such winds often bring heavy rainfall to the continents.
The unequal nature of the atmospheric circulation 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.
Fig. 2. Breeze: a - daytime; b - night
Fig. 3. The scheme of breezes: a - during the day; b - at night
Fig. 4. Monsoons: a - in the summer; b - in winter
Extra tropical 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 zone of their distribution is the 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, the pressure zones shift seasonally relative to the equator to the hemisphere in which summer is at present. Tropical monsoons are most typical and stable in the northern Indian Ocean basin. This is largely due to the seasonal change in the atmospheric pressure regime over the Asian continent. The indigenous climate of this region is associated with South Asian monsoons.
The formation of tropical monsoons in other regions of the globe is less characteristic when one of them is more clearly expressed - winter or summer monsoon. Such monsoons are observed in tropical Africa, in northern Australia and in the equatorial regions of South America.
The constant winds of the Earth - trade winds and westerly winds - depend on the position of the atmospheric pressure belts. Since in the equatorial belt low pressure prevails, and near 30 ° C. w. and y. w. - high, at the surface of the Earth throughout the year winds blow from the thirtieth latitudes to the equator. These are the trade winds. Under the influence of the Earth's rotation around the axis, the trade winds deviate to the west in the Northern Hemisphere and blow from the northeast to the southwest, while in the South they are directed from the southeast to the northwest.
From high pressure belts (25-30 ° N and S) winds blow not only to the equator, but also towards the poles, as at 65 ° N. w. and y. w. 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, westerly winds prevail.
The general circulation of the atmosphere includes trade winds, mild westerly winds, easterly (stock) winds of the polar regions, and monsoons.
Wind arises due to differences in atmospheric pressure. Since there are relatively constant belts on the Earth, it depends on them prevailing winds (they are also called permanent, prevailing, dominant or predominant).
Air masses moving with steady winds move in a certain order. They also create a complex system of air currents on a global scale. It is called the general circulation of the atmosphere (from the Latin word circulation - rotation).
Between the zones of atmospheric pressure of the earth, relatively stable prevailing winds, or winds of predominant directions, are formed.
Trade winds
Among the constant winds, the most famous are trade winds.
Trade winds - Winds that are stable throughout the year, directed from tropical latitudes to equatorial ones and generally having an eastern direction.
Passages are formed in a hot thermal zone and blow from an area of \u200b\u200bhigh pressure in the region of 30 ° C. w. and 30 ° s w. towards the equator - areas with lower pressure (Fig. 31). If the Earth did not rotate, then the winds in the Northern Hemisphere would blow precisely from north to south. But due to the rotation of the Earth, the winds deviate from the direction of their movement: in the Northern Hemisphere - to the right, and in the Southern Hemisphere - to the left. This phenomenon is called the Coriolis effect - after the name of a French scientist, and it manifests itself in relation not only to winds, but also, for example, sea currents and the washing away of the corresponding banks of large rivers (in the Northern Hemisphere - right, in the Southern - left).
The trade wind of the Northern Hemisphere is the northeast wind, and the trade wind of the Southern Hemisphere is the southeast.
The trade winds blow at a rather high speed, about 5-6 m / s, and weaken, converging near the equator, where a calm zone forms. The trade winds over the Ocean are particularly persistent. This was noted by sailors of the past, who sailed on sailing ships and were very dependent on the winds. It is believed that the name "Passat" came from Spanish vientedepasada, which means "wind conducive to moving." Indeed, during the time of the sailing fleet, they helped to travel from Europe to America.
Temperate westerly winds
From the area of \u200b\u200bincreased pressure of the hot belt, winds blow not only toward the equator, but also in the opposite direction towards temperate latitudes, where the belt of reduced pressure is also located. These winds, like the trade winds, are deflected by the rotation of the Earth (Coriolis effect). In the Northern Hemisphere, they blow from the southwest, and in the Southern Hemisphere, from the northwest. Therefore, these winds are called temperate westerly windsor western carry(fig. 31).
We are constantly confronted with the western transport of air masses at our latitudes in Eastern Europe. With westerly winds, the air of temperate latitudes from the Atlantic most often comes to us. In the southern hemisphere, latitudes, where westerly winds form over the gigantic continuous surface of the Ocean and reach tremendous speed, are called "roaring sorokalnye". Material from the site
Eastern (stock) winds of the polar regions
Eastern (stock) winds of the polar regions blow towards the belts of low pressure of moderate latitudes.
Monsoon
Sustainable winds often include monsoons. Monsoons arise due to unequal heating of land and ocean in the summer and winter. Land area is much larger in the Northern Hemisphere. Therefore, monsoons are well pronounced on the eastern coasts of Eurasia and North America, where in the middle latitudes there is a significant contrast in the warming of land and ocean. A special variety is the tropical monsoons that dominate South and Southeast Asia.
Unlike other prevailing winds, monsoons are seasonal winds. They change direction twice a year. Summer mus-son dusts from the ocean to land and brings moisture (rainy season), and the winter monsoon blows from land to the ocean (dry season).
On this page, material on topics:
Permanent temperate winds
The prevailing winds and their movement in latitudes
How the trade winds are formed and in what directions they blow
What are the permanent vertices of the polar latitudes
Do westerly winds come in constant winds
Questions about this material:
Name the constant winds above the earth's surface and explain their formation. and got the best answer
Reply from исaisiyaKonovalova [guru]
trade winds, monsoons, breezes.
Answer from 2 answers[guru]
Hello! Here is a selection of topics with answers to your question: Name the constant winds above the earth's surface and explain their formation.
Answer from Ѓrazaeva Tamila[newbie]
At some latitudes of the Earth there are high and low pressure belts. For example, atmospheric pressure is lower above the equator, because the surface of the earth is very hot there. Strong global winds, called Westerly winds and trade winds, are blowing from the high pressure belts towards the low pressure belts. However, they do not move directly from south to north and from north to south. This is due to the fact that the rotation of the Earth forces global winds to turn to the side.
Answer from DEMENKOVA AVATARIA[newbie]
about
Answer from Kazimagomed Hajibeyov[master]
google to help .. but in general this is an easy question ... topic is 6th grade.
Answer from skyrim skairim[newbie]
trade winds, monsoons, breezes.
The trade winds are formed due to the pressure drop in the tropical regions of both hemispheres and at the equator. These winds are deflected by the rotation of the Earth: the trade winds of the northern hemisphere blow from the northeast to the southwest, and the trade winds of the south - from the southeast to northwest. They are quite stable in temperature and humidity and are one of the most important factors in climate formation.
Monsoons are formed due to pressure drops resulting from temperature differences. A distinctive feature of monsoons is that in the warm and cold season they are directed in opposite directions: from sea to land and from land to sea. In winter, the air above the sea is warmer than over land, atmospheric pressure over the sea is lower, therefore, monsoons are directed from land to sea. In the warm season, the opposite is true: the air is warmer over land, a low pressure region forms there. Monsoons at this time blow to land and bring with them heavy rainfall.
In the tropical zone, monsoons are especially active, but they exist outside the tropics. Areas dominated by monsoons are characterized by very humid summers. A great example of the influence of monsoons is India, where the Himalayan mountains are stopped by a humid wind, so in northern India, Burma, Nepal there is a huge amount of rainfall.
Breezes, like monsoons, change their direction to the opposite, but this happens with a frequency of one day. These are not very large-scale winds, they are formed near the seas, oceans, large lakes, rivers. In the afternoon, the air over the land heats up, warm air rises, and cooler water comes in its place. At night, on the contrary, it is warmer above the water; colder air masses come here from land. Thus, a breeze blows from water to land during the day, and from land to water at night.
The air masses surrounding us are in continuous motion: up and down, horizontally. The horizontal movement of air we call the wind. Wind flows are formed according to their specific laws. For their characteristics, indicators such as speed, strength and direction are used.
Winds of different climatic regions have their own characteristics and features. The temperate latitudes of the Northern and Southern Hemispheres blow west winds.
Constants and Variables
Wind direction is determined by high and low pressure areas. Air masses move from places of high pressure to areas of low pressure. The direction of the wind also depends on the effect of the Earth's rotation: in the northern hemisphere, the flows are corrected to the right, in the southern - to the left. Air flows can be either constant or variable.
West winds of temperate latitudes, trade winds, northeastern and southeast winds are constant. If the trade winds are called tropic winds (30 ° N - 30 ° S), then westerly winds prevail in temperate latitudes from 30 ° to 60 ° in both hemispheres. In the Northern Hemisphere, these air currents deviate to the right.
In addition to constant, there are variable or seasonal winds - breezes and monsoons, as well as local, characteristic only for a particular region.
Westerly Current
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. Currents arising under the influence of winds are called wind. In temperate latitudes, westerly winds and the rotation of the earth directs surface currents to the western shores of the continents. In the northern hemisphere they move in the clockwise direction, in the southern hemisphere - against. In the Southern Hemisphere, the effects of wind and Earth rotation created a strong current of the West Winds along the coast of Antarctica. This is the most powerful oceanic current that spans the globe from west to east in the region between 40 ° and 50 ° 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
Westerly winds affect the climate of a large part of the continent of Eurasia, especially the part located in the temperate zone. With a breath of West, coolness comes in the midst of summer heat and a thaw in winter. It is winds from the west in collaboration with a warm ocean current that explains that the climate of north-west Europe is much warmer than the same latitudes of North America. With the advancement of the continent to the east, the influence of the Atlantic decreases, but the climate becomes completely continental only beyond the Ural ridge.
In the Southern Hemisphere, no obstacles in the form of continents and mountains interfere with the violent winds from the west, they are free and free: they storm, fight ships, rush to the east with great speed.
Who is friends with the wind
Indomitable news is especially familiar to sailors on the routes of Cape of Good Hope - New Zealand - Cape Horn. Having picked up a passing sailing ship, they can disperse it faster than a diesel vessel. Sailors call western winds brave in the Northern Hemisphere and roaring forties in the Southern Hemisphere.
The western winds brought a lot of trouble to the first aviators. They were allowed to fly from America to Europe, as they were passing. Pilots traveled the route without problems. The situation was completely different with the flight from Europe to America. Of course, there is no wind to modern supersonic airliners, but in the 20-30s of the nineteenth century it turned out to be a significant obstacle.
So the French pilots Nengesjer and Collie in 1919 made a historic flight across the Atlantic Ocean on the route Newfoundland - Azores - Iceland. But the same way in the opposite direction ended tragically. Pilots intended by air to repeat the famous Columbus route, only after 34 years were the wreckage of their plane discovered on the US coast.
The tragedy is explained by the fact that strong winds significantly delayed the aircraft, and there was simply no fuel to the destination.
The Soviet pilots Gordienko and Kokkinaki were the first to defeat the West in 1939, having successfully overcome the French route.
Preferred winds - winds that blow mainly in one direction above a specific point on the earth's surface. They are part of the global pattern of air circulation in the Earth’s atmosphere, including the trade winds, monsoons, temperate westerly winds and polar region easterly winds. In areas where global winds are weak, prevailing winds are determined by the breeze directions and other local factors. In addition, global winds may deviate from typical directions depending on the presence of obstacles.
To determine the direction of the prevailing wind, a wind rose is used. Knowing the direction of the wind allows you to develop a plan to protect farmland from soil erosion.
Wind rose - a graphical representation of the wind frequency of each direction in a given area, built in the form of a histogram in polar coordinates. Each dash in a circle shows the frequency of the winds in a particular direction, and each concentric circle corresponds to a specific frequency. The wind rose may also contain additional information, for example, each dash can be painted in different colors corresponding to a certain range of wind speeds. Wind roses often have 8 or 16 lines, corresponding to the main directions, that is, the north (N), northwest (NW), west (W), etc., or N, NNW, NW, NWW, W, etc. D., sometimes the number of dashes is 32. If the wind frequency of a certain direction or range of directions significantly exceeds the wind frequency in other directions, it is said that there are prevailing winds in this area.
Climatology
The trade winds and their influence
Temperate westerly winds and their influence
Temperate westerly winds blow in mid-latitudes between 35 and 65 degrees north or south latitude, from west to east to north of the high-pressure area, directing extratropical cyclones in the corresponding direction. Moreover, they blow harder in the winter, when the pressure above the poles is lower and weaker in the summer.
Westerly winds lead to the development of strong ocean currents in both hemispheres, but especially powerful in the southern hemisphere, where there is less land in the middle latitudes. Westerly winds play an important role in transferring warm equatorial waters and air masses to the western coasts of the continents, especially in the southern hemisphere due to the predominance of ocean space.
Eastern winds of the polar regions
Main article: Eastern winds of the polar regions
Eastern winds of the polar regions - dry cold winds blowing from the polar regions of high pressure to lower latitudes. Unlike the trade winds and westerly winds, they blow from east to west and are often weak and irregular. Due to the low angle of incidence of sunlight, cold air accumulates and settles, creating high pressure areas, pushing the air to the equator; this flow deflects west due to the Coriolis effect.
Impact of local circumstances
Sea breeze
In areas where there are no powerful air currents, an important factor in the formation of prevailing winds is the breeze. In the afternoon, the sea warms up to a greater depth than land, since water has a higher specific heat, but it is much slower than the surface of the earth. The temperature of the surface of the earth rises, and the air above it heats. Warm air is less dense and therefore it rises. This rise reduces the air pressure above the ground by about 0.2% (at sea level). Cold air above the sea, having a higher pressure, flows towards the land with a lower pressure, creating a cool breeze near the coast.
The strength of the sea breeze is directly proportional to the temperature difference between land and sea. At night, the earth cools faster than the ocean - also due to differences in their heat capacity. As soon as the land temperature drops below sea temperature, a night breeze arises - from land to sea.
Mountainous winds
In areas with uneven terrain, the natural direction of the wind can significantly change. In mountainous areas, airflow distortions are more serious. Above the hills and valleys there are strong ascending and descending flows, vortices. If there is a narrow passage in the mountain range, the wind rush through it with increased speed, according to the Bernoulli principle. At some distance from the descending air current, the air may remain unstable and turbulent, which is especially dangerous for take-off and landing aircraft.
As a result of heating and cooling of hilly slopes during the day, air flows similar to the sea breeze may appear. At night, the hillsides cool. The air above them becomes colder, heavier and descends into the valley under the influence of gravity. Such a wind is called a mountain breeze or a stock wind. If the slopes are covered with snow and ice, the stock wind will blow into the lowland throughout the day. Hillsides not covered by snow will heat up during the day. Then ascending air flows from the colder valley.
Precipitation effect
The prevailing winds have a significant effect on the distribution of precipitation near obstacles such as mountains that the wind must overcome. On the windward side of the mountains, orographic precipitation occurs due to the uplift of the air and its adiabatic cooling, as a result of which the moisture contained in it condenses and falls out in the form of precipitation. On the contrary, on the leeward side of the mountains, the air drops down and heats up, thereby reducing the relative humidity and chance of precipitation, forming rain shadow . As a result, in mountainous regions with prevailing winds, the windward side of the mountains is usually characterized by a humid climate, and the leeward - arid.
Impact on nature
Preferred winds also affect wildlife, for example, they carry insects, while birds are able to fight the wind and keep their course. As a result, prevailing winds determine the direction of insect migration. Another effect of wind on nature is erosion. To protect against such erosion, wind barriers are often built in the form of embankments, forest shelter belts and other obstacles oriented, to increase efficiency, perpendicular to the direction of the prevailing winds. The prevailing winds also lead to the formation of dunes in desert areas, which can be oriented both perpendicularly and parallel to the direction of the winds.
Notes
- URS (2008). Section 3.2 Climate conditions (in Spanish). Estudio de Impacto Ambiental Subterráneo de Gas Natural Castor. Retrieved on 2009-04-26.
- Wind rose. Archived March 15, 2012 at Wayback Machine American Meteorological Society. Retrieved on 2009-04-25.
- Jan Curtis (2007). Wind Rose Data. Natural Resources Conservation Service. Retrieved on 2009-04-26.
- Glossary of Meteorology. trade winds (unspecified) (inaccessible link). Glossary of meteorology. American Meteorological Society (2009). Date of treatment September 8, 2008. Archived August 22, 2011.
- Ralph Stockman Tarr and Frank Morton McMurry (1909). W.W. Shannon, State Printing, pp. 246. Retrieved on 2009-04-15.
- Joint Typhoon Warning Center (2006). 3.3 JTWC Forecasting Philosophies. United States Navy. Retrieved on 2007-02-11.
- Science Daily (1999-07-14). African Dust Called A Major Factor Affecting Southeast U.S. Air quality. Retrieved on 2007-06-10.
- Glossary of Meteorology. Westerlies (unspecified) (inaccessible link). American Meteorological Society (2009). Date of treatment April 15, 2009. Archived August 22, 2011.
- Sue Ferguson. Climatology of the interior columbia river basin (unspecified) (inaccessible link). Interior Columbia Basin Ecosystem Management Project (September 7, 2001). Date of treatment September 12, 2009. Archived August 22, 2011.
- Halldór Björnsson (2005). Global circulation. Archived June 22, 2012. Veðurstofu Íslands. Retrieved on 2008-06-15.
- Barbie Bischof, Arthur J. Mariano, Edward H. Ryan. The north atlantic drift current (unspecified) . The National Oceanographic Partnership Program (2003). Date of treatment September 10, 2008. Archived on August 22, 2011.
- Erik A. Rasmussen, John Turner. Polar Lows. - Cambridge University Press, 2003 .-- P. 68.
- Glossary of Meteorology (2009).
