Local winds, the reasons for their formation. Local winds Rocky Mountain foehn
Afghan- dry, baking local wind, with dust, which blows in Central Asia. It blows from several days to several weeks. Early spring with showers. Very aggressive. Barguzin- the mighty Baikal wind blows in the central part of the lake from the Barguzin Valley across and along Lake Baikal. This wind blows evenly, with gradually increasing power. Usually preceded by stable sunny weather. Bizet- cold and dry north or northeast wind in the mountainous regions of France and Switzerland. Bora- a strong gusty cold wind blowing on the coast of seas or large lakes from mountain ranges separating the very cool and warmer surface at their feet. at a speed (up to 40-60 m/s) it rolls down from the mountain ranges to the not yet frozen sea or lake. A squally wind brings severe cold, and the bora lasts from several days to a week. The shore of the Adriatic Sea, near Novorossiysk (northeast wind), on the western slope of the Urals. Breeze- local wind of low speed, changing direction twice a day. It occurs on the shores of seas, lakes, and sometimes large rivers. Therefore, the daytime breeze blows from the water area to the heated coast. Night (shore) - from the cooled coast to warm water. Mountain-valley winds are formed in mountainous areas and change their direction twice a day. The air is heated differently over the crests of mountain ranges, slopes and valley floors. During the day, the wind blows up the valley and slopes, and at night, on the contrary, from the mountains into the valley and down towards the plain. Speed 10 m/s. Zephyr- the wind that prevails in the eastern part of the Mediterranean Sea, starting in spring. Here it, although warm, often brings with it rain and even storms, while in the western part of the Mediterranean Sea Zephyr is almost always light. Mistral- On the Mediterranean coast of France there is a cold northwest wind, forming like the Novorossiysk bora. Simoom- sultry dry wind in the deserts of North Africa and the Arabian Peninsula. Samum occurs when the earth and air are strongly heated in cyclones and mainly during western and southwestern winds. The air temperature can rise to +50°C, and the relative humidity approaches 0%. The squall lasts from 20 minutes to 2-3 hours, sometimes with thunderstorms. On Lake Baikal, the boron has a local name - sarma. This wind is formed when cold arctic air passes over the coastal mountain ranges. Sirocco- a hot, dry, dusty south and southeast wind from the deserts of North Africa and the Arabian Peninsula, occurring in the front part of the cyclone. Over the Mediterranean Sea, sirocco is slightly enriched with moisture, but still dries out the landscapes of the coastal regions of France, the Apennine and Balkan peninsulas. Most often it blows in the spring for 2-3 days in a row, raising the temperature to 35°C. Crossing the mountains, on their leeward slopes it acquires the character of a foehn. Sukhovey- wind with high temperature and low relative humidity in steppes, semi-deserts and deserts, forms along the edges of anticyclones and continues for several days, increasing evaporation, drying out the soil and plants. Dry winds are characteristic of the steppe regions of Russia and Ukraine, Kazakhstan and the Caspian region. Föhn- a dry, warm, strong wind, blowing gustyly from high mountains to valleys. Föhn is well expressed in the Alps, the Caucasus, and the mountains of Central Asia. Khamsin- dry, swelteringly hot wind from the south in northeast Africa and the Middle East. The temperature is 40°C, sometimes it blows 50 days a year, usually in March-May. Occurs in the leading parts of cyclones moving from the deserts of North Africa. Chinook- southwestern foehn on the eastern slopes of the Rocky Mountains in Canada and the USA, as well as on the adjacent prairie areas. Accompanied by a very rapid, sharp increase in air temperature, Chinook is also called a moist southwesterly wind from the Pacific Ocean to the west coast of the United States. The reason for their formation may be different temperature conditions on the shores of lakes or rivers, in mountains and valleys. Some of them are essentially air currents of the general circulation of the atmosphere, but in a certain area they have special properties. The occurrence of local winds is associated mainly with the difference in temperature conditions over large bodies of water (breezes) or mountains, their extension relative to general circulation flows and the location of mountain valleys (fen, bora, mountain-valley), as well as with changes in the general circulation of the atmosphere by local conditions (the very , sirocco, khamsin). Some of them are essentially air currents of the general circulation of the atmosphere, but in a certain area they have special properties, and therefore they are classified as local winds and given their own names.
Local winds are local, regional circulation systems. They are characteristic of certain geographical areas. Their origin is also different. Manifestations of local circulation, independent of the general circulation of the atmosphere, include breezes and mountain-valley winds. Local winds may be influenced by the orography or topography of the area. These include hairdryer, bora, sirocco and others.
Adriatic bora- a cold winter wind passing through the Dinaric Mountains. One of the most characteristic representatives of this type of winds, along with the Novorossiysk and Novaya Zemlya forests.
Ae– dry, scorching trade wind on the Hawaiian Islands.
Antillean hurricanes– tropical cyclones observed in the Caribbean Sea and the Gulf of Mexico.
Afghan (Awgon Chamoli)– local southwest wind, very dusty, blowing in the area of the upper reaches of the Amu Darya.
Bad-i-sad-au-bistrose, wind 120 days– strong wind flow from the Parapamiz pass, common from May to September.
Baku Nord– local northern wind such as bora on the Absheron Peninsula, associated with intrusions of cold air.
Biza- north or northeast wind in the mountainous regions of France and Switzerland, similar to the mistral, cold and dry. Observed during invasions of cold air masses.
Blizzard– a blizzard with a strong northwest wind and low temperature, in the rear of a cyclone (in North America, England and polar countries, including Antarctica).
Buran– a blizzard with strong winds and low temperatures.
Storm– very strong wind with a speed of 20 m/sec and above, accompanied by significant disturbances at sea and destruction on land. B. is usually associated with the passage of intense cyclones.
Garmsil– a dry hot wind in the foothills of the Kopetdag and western Tien Shan, blowing in the summer from the south and east. Has the character of a hairdryer.
Doctor– a pleasant refreshing daytime breeze with this name is observed on the coasts of Jamaica, Western India, and South Africa. In southwest Australia it is called: Albany Doctor, Perth Doctor, Esperance Doctor, Eucla Doctor, Fremantle Doctor.
Glacial Wind (katabatic wind) is a wind blowing over a glacier downstream, from the cooler upper part to warmer areas (in mountain valleys, above the sea). Caused by air cooling by the ice surface. Most typical for Greenland and Antarctica. In Antarctica, glacial (katabatic) winds reach speeds of 40-60 m/sec or more. The maximum speed of such wind is 300-305 km/h.
Mistral– a strong and cold northwest wind on the Mediterranean coast of France in the Rhone Valley. Similar to bora.
Novaya Zemlya Bora- a cold wind passing through the mountains of Novaya Zemlya from the Kara Sea to the Barents Sea.
Pampero– cold gale wind from the south in Argentina and Uruguay, sometimes with rain and thunderstorms. Associated with the passage of cold fronts and incursions of Antarctic air.
Saikan– a hurricane westerly wind in the Alakol depression and on Lake Alakol in eastern Kazakhstan, blowing from the Saikan gorge in the Dzhungar Alatau.
Ate myself– dry winds of the opposite direction in the Kura valley, in summer.
Simoom- the local name for the dry hot wind in the deserts of Arabia and. S. is a squall with a sandstorm, often with a thunderstorm.
Sarma– a strong bora-type wind blowing from the Primorsky Ridge to the surface of the lake. Baikal near the mouth of the river. Sarma at speeds up to 40 m/sec. Maximum frequency in October-December.
Sirocco– a strong warm wind of the southern and southeastern direction in the front part of the cyclone in the Mediterranean basin. In the Apennine and western parts of the Balkan Peninsula. The air in the north is usually humid; on the Arabian Peninsula and Mesopotamia it is dry and contains sandy dust.
Tornado– a strong atmospheric vortex with a vertical axis several tens of meters long. Originates under a cumulonimbus cloud and moves with it; exists from several minutes to several tens of minutes. Wind speeds in the north can reach 50-100 m/sec with a strong upward component. Usually cause significant damage.
Sukhovey– wind at high temperatures and low relative humidity in the steppes and semi-deserts of Eurasia, harmful or destructive for field crops. With S., evaporation increases, which, if there is a lack of moisture in the soil, leads to withering and death of plants.
Typhoon- the name of tropical cyclones of storm and hurricane force in the Far East. T. arise mainly in summer and autumn in the ocean to the east and west of the Philippine Islands and in their further development can reach the coasts of China, Japan, Korea, and Russia.
Tehuantepequero– strong winter (usually from November to March) bora-type wind on the Pacific coast of Mexico. It blows across the Isthmus of Tehuantepec towards the Gulf of the same name when continental air from temperate latitudes invades the Gulf of Mexico.
Tornado- name of blood clots. They are especially common in the southeastern United States, where several hundred T. are observed annually.
Tramontane– a strong and dry wind, similar in type to the foehn in the Mediterranean, accompanied by good weather. Three more types of winds have a similar name.
Tramontana (1)-Bora-type wind (from the Alps to the Padan lowland), sometimes takes on the characteristics of a foehn.
Tramontana (2)– a cold bora-type wind in Northern and Central Italy, the direction is mainly northeast. Accompanied by clear weather, typical in winter.
Tramontana (3)- a cold and stormy gusty wind from the Pyrenees to the Balearic Sea, accompanied by clear and dry weather.
Thrombus- a strong whirlwind (tornado) over land with a diameter of several tens of meters, arising under a thundercloud. Wind speeds there reach 50-100 m/sec, and the destruction strip is hundreds of meters wide. Occurs in hot weather with sharply unstable stratification of the atmosphere. In the USA it is called a tornado.
Hurricane– wind of destructive force and considerable duration, with a speed of 30 m/sec or more.
Haboob– a strong sand or dust storm in Sudan. Most often, H. occurs from May to October.
Khamsin– dry, hot, dusty south wind in northeast Africa, especially frequent in spring, when cyclones pass over the Mediterranean Sea or northern Sahara. In Arabic, H. is 50, since the wind blows for approximately 50 days.
Harmattan, harmattan- a dry, hot, dusty northeast wind that blows in winter in West Africa, in the area of the Cape Verde Islands and the Gulf of Guinea. In essence, X. is a winter monsoon.
Chinook(“snow eater”) is the local name for the southwest foehn on the eastern slopes of the Rocky Mountains in Canada and the United States. The same name has the moist wind from the ocean in the Western Cordillera, bringing cloudy rainy weather, warm in winter and cool in summer.
Squalls– sharp gusty wind increases. There are intramass, in the leading part of cumulonimbus clouds, and frontal, formed during the passage of a cold front.
Ethesia– moderate to strong northerly or northwesterly winds over the northern Mediterranean towards Africa. Observed from mid-May to mid-October. They can blow continuously for up to 40 days. They arise when a spur of the Azores anticyclone appears over Southern Europe, and a low pressure zone forms over heated Western Asia. E. bring haze and fog to the northern shores of Africa. Sometimes it covers territories from the Pyrenees to Syria and the Bosphorus. During the period of night weakening it is called “sleeping wind”.
Literature
- Zubaschenko E.M. Regional physical geography. Climates of the Earth: educational and methodological manual. Part 1. / E.M. Zubaschenko, V.I. Shmykov, A.Ya. Nemykin, N.V. Polyakova. – Voronezh: VSPU, 2007. – 183 p.
The occurrence of local winds is associated mainly with the difference in temperature conditions over large bodies of water (breezes) or mountains, their extension relative to general circulation flows and the location of mountain valleys (fen, bora, mountain-valley), as well as with changes in the general circulation of the atmosphere by local conditions (the very , sirocco, khamsin). Some of them are essentially air currents of the general circulation of the atmosphere, but in a certain area they have special properties, and therefore they are classified as local winds and given their own names.
For example, only on Baikal, due to the difference in heating of water and land and the complex arrangement of steep ridges with deep valleys, at least 5 local winds are distinguished: Barguzin - a warm northeastern wind, mountain - a northwestern wind that causes powerful storms, sarma - a sudden westerly wind, reaching hurricane force up to 80 m/s, valleys - southwestern kultuk and southeastern shelonik.
Afghan
Afghan is a dry, baking local wind, with dust, that blows in Central Asia. It has a southwestern character and blows in the upper reaches of the Amu Darya. It blows from several days to several weeks. Early spring with showers. Very aggressive. In Afghanistan it is called kara-buran, which means black storm or body shuravi - Soviet wind.
Barguzin
Barguzin - the mighty Baikal wind, mentioned in the song “The Glorious Sea - Sacred Baikal”, blows mainly in the central part of the lake from the Barguzin Valley across and along Lake Baikal. This wind blows evenly, with gradually increasing power, but its duration is noticeably shorter than that of Verkhovik. Usually preceded by stable sunny weather.
Biza
Bise (French Bise) is a cold and dry north or northeast wind in the mountainous regions of France and Switzerland. Bizet is similar to bora.
Bora
Bora (Italian bora from the Greek boreas - north wind) is a strong gusty cold wind blowing on the coast of seas or large lakes from mountain ranges that separate the very cool and warmer (especially coastal) surface at their feet. It forms when low mountain ranges separate cold air over land from warm air over water. This wind is most dangerous in frosty weather, when it rolls down mountain ranges at high speed (up to 40-60 m/s) to a sea or lake that has not yet frozen. Over a warm water surface, the temperature contrast between the flow of cold air and the warm sea increases significantly, and the speed of the bora increases. A squally wind brings severe cold, raises high waves, and splashes of water freeze on the hulls of ships. Sometimes a layer of ice up to 4 meters thick grows on the windward side of the ship, under the weight of which the ship can capsize and sink. The bora lasts from several days to a week. The bora is especially typical on the Yugoslav coast of the Adriatic Sea, near Novorossiysk (northeast wind), on the western slope of the Urals - the eastern Kizelovskaya bora and others. A special type of bora is the katabatic wind in Antarctica and on the northern island of Novaya Zemlya.
Breeze
Breeze (French brise - light wind) is a local wind of low speed, changing direction twice a day. It occurs on the shores of seas, lakes, and sometimes large rivers. During the day, land warms up faster than water, and lower atmospheric pressure sets over it. Therefore, the daytime breeze blows from the water area to the heated coast. Night (shore) - from the cooled coast to warm water. Breezes are well expressed in summer during stable anticyclonic weather, when the difference in temperature between land and water is most significant. Breezes cover a layer of air of several hundred meters and on the seas operate within a range of several tens of kilometers. In the era of sailing, breezes were used to begin sailing.
Garmattan
Harmattan is a dry and sultry wind that blows on the Guinea coast of Africa and brings red dust from the Sahara.
Garmsil
Garmsil (Taj.Garmsel) is a dry and hot wind like a foehn, blowing mainly in summer from the south and southeast in the foothills of the Kopetdag and Western Tien Shan.
Mountain-valley winds
Mountain-valley winds form in mountainous areas and change their direction twice a day. The air is heated differently over the crests of mountain ranges, slopes and valley floors. During the day, the wind blows up the valley and slopes, and at night, on the contrary, from the mountains into the valley and down towards the plain. The speed of mountain-valley winds is low - about 10 m/s.
Marshmallow
Zephyr (Greek Ζέφυρος, “western”) is the wind that dominates the eastern part of the Mediterranean Sea, starting in spring, and reaching its greatest intensity by the summer solstice. Here, although it is warm, it often brings with it rain and even storms, while in the western part of the Mediterranean Sea Zephyr is almost always a light, pleasant wind.
Mistral
On the Mediterranean coast of France, a cold northwest wind, formed like the Novorossiysk bora, is called mistral, and a similar wind on the coast of the Caspian Sea in the Baku region is called north.
Pampero
Simoom
Samum is a sultry dry wind in the deserts of North Africa and the Arabian Peninsula. Usually, before an approaching squall of a simoom, the sands begin to “sing” - the sound of grains of sand rubbing against each other can be heard. Raised “clouds” of sand obscure the Sun. Samum occurs when the earth and air are strongly heated in cyclones and mainly during western and southwestern winds. The wind carries hot sand and dust and is sometimes accompanied by a thunderstorm. The air temperature can rise to +50 °C, and the relative humidity approaches 0%. The squall lasts from 20 minutes to 2-3 hours, sometimes with thunderstorms. When doing samum, you should lie down and cover yourself tightly with clothes. In the Algerian Sahara it happens up to 40 times a year.
Sarma
On Lake Baikal, the boron has a local name - sarma. This wind is formed when cold arctic air passes over the coastal mountain ranges. It is named after the Sarma River, through the valley of which the cold wind from Yakutia breaks through to Baikal. In 1912, this icy wind tore a huge barge from its tug and threw it onto a rocky shore. As a result, more than 200 people died.
Sirocco
Sirocco (Italian Scirocco - strong) is a hot, dry, dusty south and southeast wind from the deserts of North Africa and the Arabian Peninsula, occurring in the front of the cyclone. Over the Mediterranean Sea, sirocco is slightly enriched with moisture, but still dries out the landscapes of the coastal regions of France, the Apennine and Balkan peninsulas. Most often it blows in spring for 2-3 days in a row, raising the temperature to 35 °C. Crossing the mountains, on their leeward slopes it acquires the character of a foehn. The Sirocco wind brings to Southern Europe not only the red and white dust from the Sahara, which falls with the rains, turning them bloody or milky, but also suffocating heat.
Sukhovey
Dry wind is a wind with high temperature and low relative humidity in steppes, semi-deserts and deserts; it forms along the edges of anticyclones and lasts for several days, increasing evaporation, drying out the soil and plants. The speed of the dry wind is usually moderate, the relative humidity is low (less than 30%). Dry winds are characteristic of the steppe regions of Russia and Ukraine, Kazakhstan and the Caspian region.
Tornado
Tornado (Spanish: Tornado) - in North America, a strong atmospheric vortex over land, characterized by exceptionally high frequency, is formed as a result of the collision of cold masses from the Arctic and warm masses from the Caribbean. Several hundred tornadoes occur in the eastern United States each year.
Föhn
Foehn (German Fohn, from Latin Favonius - warm western wind) is a dry, warm strong wind blowing gustily from high mountains to valleys. It is observed in all mountainous countries. The air flows over the crest of the ridge, rushes along the leeward slope into the valley, and as it descends, its temperature rises and humidity decreases as a result of adiabatic heating - by one degree for every 100 m of descent. The greater the height from which the foehn descends, the higher the temperature of the air it brings rises. The speed of the hair dryer can reach 20-25 m/s. In winter and spring, it causes rapid melting of snow, avalanches, increased evaporation from soil and vegetation cover, and the level of mountain rivers. In summer, its drying breath is destructive to plants; Sometimes in Transcaucasia, the summer foehn causes the foliage on the trees to dry out and fall off. Usually lasts less than a day, occasionally up to 5 or more. Föhn is well expressed in the Alps, the Caucasus, and the mountains of Central America.
Khamsin
Khamsin (Arabic literally fifty) is a dry, swelteringly hot wind from the south in northeast Africa and the Middle East. The air temperature is often above 40 °C; with gale force winds, khamsin sometimes blows 50 days a year, usually in March-May. Occurs at the front of cyclones moving from the deserts of North Africa, so khamsin is filled with sand and dust, reducing visibility.
Chinook
Chinook (English chinook, from the name of the Chinook Indian tribe) is a southwestern foehn on the eastern slopes of the Rocky Mountains in Canada and the United States, as well as on the adjacent prairie areas. It is accompanied by a very rapid, sharp (sometimes by 20-30°C) increase in air temperature, which contributes to increased snow melting, accelerated fruit ripening, etc. Chinook is observed in all seasons of the year, but especially often in winter. Chinook is also the name given to the moist southwest wind from the Pacific Ocean to the West Coast of the United States.
Notes
Literature
- Meteorology and climatology. Leningrad, 1968 Author – Khromov S.P.
- Prokh L.Z. Dictionary of winds. - L.: Gidrometeoizdat, 1983. - 28,000 copies.
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See what “Local winds” are in other dictionaries: LOCAL WINDS
- local air circulation - air currents of small horizontal extent (from hundreds of meters to tens of kilometers), arising as a result of local disturbance of a larger air flow under the influence of orographic features and ... ... Wind Dictionary Winds in limited areas, distinguished by their speed, frequency, direction or other features. Under this general name winds of various origins are united: 1) local circulations independent of air currents... ...
Great Soviet Encyclopedia
Winds that arise in any point or small area according to local conditions, for example: bora, Baku north, foehn, etc. Samoilov K.I. Marine Dictionary. M. L.: State Naval Publishing House of the NKVMF of the USSR, 1941 ... Marine Dictionary WINDS OF FORCED CONVECTION
- local winds arising from mechanical disturbance of air flows by mountain obstacles. For example, runoff, bora, mountain valley winds... Wind dictionary
2. If a tailwind is observed during the flight, it is necessary to use it. In this case, it is recommended to fly in its central part or on the right side.
4. The ST can be crossed 1.5…2.0 km below the axis or above the tropopause.
5. If you enter a bumpy area associated with a downwind ST, you must change flight level or deviate to the right (taking into account the temperature deviation from the ST).
7. When an ST is detected, the aircraft commander must immediately inform the controller about its direction, speed and phenomena associated with it.
8. You can detect a ST in flight by cloud stripes stretching along its direction,
and on the demolition of the aircraft, in this case:
If a strong left drift is observed and the air temperature rises, then the aircraft enters the ST from the left side;
If there is a strong right drift and the air temperature decreases, then the aircraft enters the ST from the right side;
If during horizontal flight along the ST the air temperature remains constant and the ground speed increases (decreases), then the ST is tailwind (headwind).
In certain areas, under the influence of local physical and geographical conditions, air currents are formed that have a relatively small horizontal and vertical extent and differ in characteristic features. Such air currents are called local winds . They can arise due to uneven heating of the underlying surface (land, water, mountain slopes and valleys) or due to the peculiarities of air flow around orographic obstacles. Local winds include breezes, mountain-valley winds, glacial winds, bora, foehn and others.
Breezes- these are winds with daily periodicity that occur on the coasts of seas, large lakes and wide rivers. The reason for their occurrence is uneven heating and cooling of land and sea during the day, approx.
Daytime (sea) breeze blows from a cold water surface onto a heated land, and night (shore) breeze - from cooled land to a warmer water surface (Fig. 10.7).
The sea breeze appears around 9...11 a.m. local time, spreads inland to 20...40 km, its vertical thickness reaches several hundred meters (sometimes up to 1000 m). Maximum speeds reach 4...6 m/s and are observed in the afternoon.
The coastal breeze forms after sunset and during the night penetrates 8...10 km deep into the sea.
Rice. 10.7. Breeze circulation formation scheme
In temperate latitudes, breezes are observed in the warm half of the year; they are more clearly expressed in clear weather, if the general air transport is absent or weakened. Above the breeze there is a wind of the opposite direction of approximately the same vertical power, called antibreeze .
Well-developed breezes are observed on the Black, Azov and Caspian Seas, weaker on the White Sea, on Lakes Ladoga and Onega. In tropical areas, breezes are observed all year round.
When flying in areas where breeze circulation is observed, it is necessary to take into account the change in wind directions near the ground and at the height of the circle in the morning and evening hours.
Mountain-valley winds- like breezes, they have a daily periodicity and arise due to uneven heating and cooling of mountain slopes and valleys day and night (Fig. 10.8).
Rice. 10.8. Scheme of formation of mountain-valley winds
During the day, mountain slopes and the air adjacent to them heat up faster and more strongly than air away from the slopes. As a result, lighter warm air rises up the mountain slopes. This wind is called valley .
At night, the mountain slopes and the air adjacent to them cool faster than the air removed from the slopes. Therefore, colder air falls down along the slopes. This is how it will be formed mountain wind .
The speed of valley winds usually does not exceed 3...6 m/s, and the speed of mountain winds
can reach 20 m/s or more. This can lead to severe bumpiness and sudden downward thrusts of aircraft.
Glacial winds blow over the glacier downstream of the glacier. They do not have a daily periodicity, because the glacier cools the air throughout the day. There is usually an inversion above the glacier, so cold air blows (flows) down. Over the glaciers of the Caucasus, the speed of such winds reaches 5...7 m/s. Glacial winds in
observed on a huge scale in Antarctica. Here they are called katabatic winds . Due to the fact that the movement of air in this case is influenced not only by the force of the horizontal baric gradient, but also by the force of gravity of the Earth, the speed of katabatic winds reaches 20 m/s or more.
Bora- this is a strong cold gusty wind that occurs when cold air falls from low coastal mountains onto the coast and a fairly warm sea. The most famous is the Novorossiysk bora (on average 46 days a year) on the northeastern coast of the Black Sea (Fig. 10.9).
Rice. 10.9. Scheme of the Novorossiysk forest in the stage of collapse
It is formed in those cases when an area of high pressure is established over the Krasnodar Territory of Russia, and low pressure is established over the Black Sea. The cold air mass accumulates in front of the Markhotsky pass (height 450 m) and, reaching its peak in front of Novorossiysk, falls down. Wind speed reaches 40...60 m/s or more. Cold air, mixing with warm air near the surface of the sea, reaches a state of saturation. If the air temperature is below 0°C, favorable conditions are created for the formation of ice.
Local bora-type winds in various geographical areas are called: Sarma - near the Olkhovsky Gate on Lake Baikal; Nord - in the Baku region; Mistral - on the Mediterranean coast of France (from Montpellier to Toulon); Northser - in the Gulf of Mexico (Mexico, Texas); Oroshi is on the ocean coast of Japan.
Föhn- this is a dry, warm, gusty wind that occurs when air currents cross large mountain ranges and spreads far into the plain. It can be observed at any time of the year and day. The main reason for its formation is the flow of air over the top of the mountain. Relatively warm air rises up along the windward slope and is cooled to a condensation level of 1°C for every 100 m, above the condensation level - by an average of 0.5°C for every 100 m. The rise of air will be accompanied by condensation of water vapor, the formation clouds and precipitation (Fig. 10.10). Having reached the top of the mountain, the air will begin to flow over it and fall along the slope on the leeward side of the mountain. As it descends, the air will warm up by 1° per 100 m; as a result, the clouds on the leeward side are washed away, and the air in the valley arrives dry and warm.
Rice. 10.10. Föhn formation diagram
Changes in temperature and humidity can be very rapid and dramatic:
In 1…2 hours the temperature can rise by 30…40°C. The duration of the foehn varies from several hours to 5 days or more. The foehn speed fluctuates from calm to 15...20 m/s; foehn speeds of 30...40 m/s were observed.
When flying in areas where foehn is observed, suction may occur.
aircraft towards the mountain, sometimes there are sharp drops down.
Foehn can occur in all mountainous regions, they are especially frequent in the Alps,
The Carpathians, the Caucasus, the mountains of Central Asia and the Far East.
1. Breeze.
2. Mountain-valley winds.
3. Glacial winds.
4. Hair dryer.
5. Bora.
6. Squalls.
7. Atmospheric vortices of small sizes.
Local wind is the wind in a certain limited area, which has characteristic features explained by the geography of this area.
He can be:
the result of the influence (usually reinforcing) of local topography or orography on the currents of the general circulation of the atmosphere (foehn, bora, mistral, pass wind, canyon wind);
manifestation of local circulation, independent of the general circulation of the atmosphere (breeze, mountain-valley wind);
manifestation of convection, sometimes of a vortex nature (dust storm, haboob, etc.);
the flow of the general circulation of the atmosphere with properties special for a given area: dryness, dust, low temperature at a significant speed (Afghan, Sirocco, Buran, Khamsin, Samum). Winds of this category have numerous names in different regions of the Earth.
1. Breeze
Breeze(from French. brise- light wind) is a wind with daily frequency along the shores of seas and large lakes, as well as on some large rivers.
Breezes are formed due to temperature differences associated with unequal specific heat capacity, thermal conductivity, and what about the different albedo of land and reservoir.
They are associated with the daily variation of air temperature.
The daytime breeze blows from the sea (water surface) onto the heated coast (Figure 78). It is also called sea. During the day, land, whose specific heat capacity is less than water, heats up more. The air above it also heats up more. Therefore, isobaric surfaces above land rise somewhat. Above the surface of the earth (at a certain height), the outflow of air begins towards the sea, and in the surface part - in the opposite direction. Because the movement develops over a short time, the Coriolis force cannot balance the pressure gradient. The wind deviates from the geostrophic one, i.e. does not blow along the coastline, but crosses it. The sea breeze is stronger than the night shore breeze because... the differences between the temperature of land and water surfaces are greater during the day than at night.
The night breeze blows in the opposite direction to the daytime one. At night, land in coastal areas cools faster than the body of water. In this case, the air over land quickly cools due to thermal conductivity and becomes denser. Isobaric surfaces over land sink. At heights, air transfer occurs, directed from the reservoir to the land. An area of low pressure is created above the water surface. Then the air in the surface part begins to move from land to the body of water.
Wind speed in breezes is 3–5 m/s, in the tropics and more. During the passage of cyclones, breezes are masked by the general transfer of air. Breezes capture a layer of air up to 1–2 km in height (daytime is larger than nighttime). Deep into the sea or land, breezes extend for tens of kilometers.
The sea breeze brings cooling and an increase in relative air humidity (temperature drops by 2–3°C (in West Africa by 10°C), humidity increases by an average of 10–20% (up to 40%).