Characteristics of atmospheric vortices

Characteristics of hurricanes, storms, tornadoes

Hurricanes, storms, tornadoes are wind meteorological phenomena , belong to natural disasters , can cause great material damage and lead to death of people.

Wind is the movement of air relative to the earth’s surface, resulting from the uneven distribution of heat and atmospheric pressure. The main indicators of wind are direction (from a high pressure zone to a low pressure zone) and speed (measured in meters per second (m/s; km/h; miles/hour).

Many words are used to indicate the movement of the wind: hurricane, storm, storm, tornado … To systematize them, they use the Beaufort scale (developed by the English admiral F. Beaufort in 1806) , which allows you to very accurately assess the strength of the wind in points (from 0 up to 12) according to its effect on land objects or on waves in the sea. This scale is also convenient in that it allows, according to the signs described in it, to fairly accurately determine the wind speed without instruments.

Beaufort scale (Table 1)

Beaufort points Verbal definition of wind strength Wind speed, m/s (km/h) The action of the wind on land
On the land On the sea
Calm 0.0 – 0.2 (0.00-0.72) Calm. Smoke rises vertically Mirror-smooth sea
Quiet breeze 0.3 -1.5 (1.08-5.40) The direction of the wind can be seen from the drift of the smoke, Ripples, no foam on the ridges
light breeze 1.6 – 3.3 5.76-11.88) The movement of the wind is felt by the face, the leaves rustle, the weather vane moves Short waves, crests do not tip over and appear glassy
Weak breeze 3.4 – 5.4 (12.24-19.44) Leaves and thin branches of trees sway, the wind blows the top flags Short well defined waves. Combs, tipping over, form foam, occasionally small white lambs are formed.
moderate breeze 5.5 -7.9 (19.8-28.44) 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.
fresh breeze 8.0 -10.7 (28.80-38.52) 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.
strong breeze 10.8 – 13.8 (38.88-49.68) The thick branches of the trees are swaying, the wires are buzzing Large waves begin to form. White foamy ridges occupy large areas.
strong wind 13.9 – 17.1 (50.04-61.56) 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 wind (storm) 17.2 – 20.7 (61.92-74.52) 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. Strips of foam fall in rows in the wind.
Storm (strong storm) 20.8 -24.4 (74.88-87.84) 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 overturn and crumble into spray.
Severe storm (total storm) 24.5 -28.4 (88.2-102.2) Significant destruction of buildings, trees uprooted. Rarely on land Very high waves with long downward bending crests. The foam is blown up by the wind in large flakes in the form of thick stripes. The surface of the sea is white with foam. The roar of the waves is like blows. Visibility is poor.
Violent storm (violent storm) 28.5 – 32.6 (102.6-117.3) Large destruction over a large area. Very rare on land Exceptionally high waves. Vessels are sometimes out of sight. The sea is covered with long flakes of foam. The edges of the waves are everywhere blown into foam. Visibility is poor.
Hurricane 32.7 or more (117.7 or more) Heavy objects are carried by the wind over long distances. The air is filled with foam and spray. The sea is all covered with strips of foam. Very poor visibility.

Characteristics of atmospheric vortices

Atmospheric vortices Local name Characteristic
Cyclone (tropical and extratropical) – eddies with low pressure at the center Typhoon (China, Japan) Bagweese (Philippines) Willy Willy (Australia) Hurricane (North America) Eddy diameter 500-1000 km Height 1-12 km Calm area diameter (“eye of the storm”) 10-30 km Wind speed up to 120 m/s Duration – 9-12 days
A tornado is an ascending vortex consisting of rapidly rotating air mixed with particles of moisture, sand, dust and other suspensions, an air funnel descending from a low cloud onto a water surface or land Tornado (USA, Mexico) Thrombus (West Europe) The height is several hundred meters. The diameter is several hundred meters. Travel speed up to 150-200 km/h Whirlpool rotation speed up to 330 m/s
Squall – short-term whirlwinds that occur in front of cold atmospheric fronts, often accompanied by a shower or hail and occur in all seasons of the year and at any time of the day. Storm Wind speed 50-60 m/s Action time up to 1 hour
A hurricane is a wind of great destructive power and considerable duration, which occurs mainly from July to October in the zones of convergence of a cyclone and an anticyclone. Sometimes accompanied by showers. Typhoon (Pacific Ocean) Wind speed over 29 m/s Duration 9-12 days Width – up to 1000 km
A storm is a wind that is slower than a hurricane. Storm Duration – from several hours to several days Wind speed 15-20 m/s Width – up to several hundred kilometers

Hurricane

A hurricane is a fast wind movement, with a speed of 32.7 m / s (117 km / h), although it can exceed 200 km / h (12 points on the Beaufort scale) (Table 1), with a significant duration of several days ( 9-12 days), continuously moving over the oceans, seas and continents and possessing great destructive power. The width of the zone of catastrophic destruction is taken as the width of the hurricane. Often, the area of storm force winds with relatively little damage is added to this zone. Then the width of the hurricane is measured in hundreds of kilometers, sometimes reaching 1000 km. Hurricanes occur at any time of the year, but most often from July to October. In the remaining 8 months they are rare, their paths are short.

A hurricane is one of the most powerful manifestations of nature, in its consequences it is comparable to an earthquake. Hurricanes are accompanied by a large amount of precipitation and a decrease in air temperature. The width of the hurricane is from 20 to 200 kilometers. Most often, hurricanes sweep over the USA, Bangladesh, Cuba, Japan, the Antilles, Sakhalin, and the Far East.

In half of the cases, the wind speed during a hurricane exceeds 35 m/s, reaching up to 40-60 m/s, and sometimes up to 100 m/s. Hurricanes are classified into three types based on wind speed:

– hurricane (32 m/s and more),

– strong hurricane (39.2 m/s and more)

– a severe hurricane (48.6 m/s or more).

The reason for such hurricane winds is the occurrence, as a rule, on the collision line of fronts of warm and cold air masses, powerful cyclones with a sharp pressure drop from the periphery to the center and with the creation of a vortex air flow moving in the lower layers (3-5 km) in a spiral towards middle and up, in the northern hemisphere – counterclockwise. Forecasters assign each hurricane a name or a four-digit number.

Cyclones [1] , depending on the place of their occurrence and structure, are divided into:

1) Tropical cyclones occur over warm tropical oceans, usually move west during formation, and bend poles after formation. A tropical cyclone that has reached unusual strength is called:

– a tropical hurricane if it is born in the Atlantic Ocean and adjacent seas. North and South America. Hurricane (Spanish huracán, English hurricane) named after the Mayan wind god Huracan;

typhoon – if it originated over the Pacific Ocean. Far East, Southeast Asia;

cyclone – in the Indian Ocean region.

Rice. Structure of a tropical cyclone

The eye is the central part of the cyclone in which the air descends.

The wall of the eye is a ring of dense thunderstorm cumulus clouds surrounding the eye.

The outer part of a tropical cyclone is organized into rainbands – bands of dense thunderstorm cumulus clouds that slowly move towards the center of the cyclone and merge with the wall of the eye.

One of the most common definitions of the size of a cyclone, which is used in various databases, is the distance from the center of circulation to the outermost closed isobar, this distance is called the radius of the outer closed isobar.

2) Cyclones of moderate latitudes can form both over land and over water. They usually move from west to east. A characteristic feature of such cyclones is their great “dryness”. The amount of precipitation during their passage is much less than in the zone of tropical cyclones.

3) The European continent is affected by both tropical hurricanes that originate in the central Atlantic and cyclones of temperate latitudes.

Rice. Hurricane Isabel 2003, photograph from the ISS – you can clearly see the characteristic eyes of tropical cyclones, the wall of the eye and the surrounding rain bands.

Storm (storm)

A storm (storm) is a type of hurricane that is inferior to it in strength. Hurricanes and storms differ only in wind speed. A storm is a strong, prolonged wind, but its speed is less than that of a hurricane of 62 – 117 km / h (8 – 11 points on the Beaufort scale). A storm can last from 2-3 hours to several days, covering a distance (width) from tens to several hundred kilometers. A storm that breaks out at sea is called a storm.

Depending on the color of the particles involved in the movement, there are: black, red, yellow-red and white storms.

Depending on the wind speed, storms are classified:

Beaufort points Verbal definition of wind strength Wind speed, m/s (km/h) The action of the wind on land
On the land On the sea
Very strong wind (storm) 17.2 – 20.7 (61.92-74.52) 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. Strips of foam fall in rows in the wind.
Storm (strong storm) 20.8 -24.4 (74.88-87.84) 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 overturn and crumble into spray.
Severe storm (total storm) 24.5 -28.4 (88.2-102.2) Significant destruction of buildings, trees uprooted. Rarely on land Very high waves with long downward bending crests. The foam is blown up by the wind in large flakes in the form of thick stripes. The surface of the sea is white with foam. The roar of the waves is like blows. Visibility is poor.
Violent storm (violent storm) 28.5 – 32.6 (102.6-117.3) Large destruction over a large area. Very rare on land Exceptionally high waves. Vessels are sometimes out of sight. The sea is covered with long flakes of foam. The edges of the waves are everywhere blown into foam. Visibility is poor.

Storms are divided into:

1) Vortex – are complex vortex formations caused by cyclonic activity and spreading over large areas. They are:

– Sandstorms (dust storms) – which are played out in deserts, carry thousands of tons of sand and dust. In addition to a sharp deterioration in visibility, they are also dangerous due to high air temperature. Dust storms cause suffocation and lead to diseases (they carry various parasites), and equipment suffers to a large extent.

Snow storms (winter) are formed in winter. Such storms are called snowstorms, snowstorms, snowstorms. Accompanied by severe frost and blizzard, they can move huge masses of snow over long distances, which leads to heavy snowfalls, blizzards, snow drifts. Snow storms paralyze traffic, disrupt power supply, and lead to tragic consequences. The wind contributes to the cooling of the body, frostbite.

Squall storms arise suddenly, and in time are extremely short (several minutes). For example, within 10 minutes the wind speed can increase from 3 to 31 m/s.

2) Stream storms are local phenomena of small distribution, weaker than whirling storms. Pass most often between the chains of mountains connecting the valleys. Subdivided into:

– Stock – the air flow moves down the slope.

– Jet – the air flow moves horizontally or up the slope.

Rice. Storm (storm.) Work on the masts of a sailing ship in a storm.

Tornado (tornado)

Tornadoes (in the English terminology tornado from Spanish tornar “twist, twist”) is an atmospheric vortex in the form of a dark sleeve with a vertical curved axis and a funnel-shaped extension in the upper and lower parts. The air rotates at a speed of 50-300 km / h counterclockwise and rises in a spiral. Inside the stream, the speed can reach 200 km / h. Inside the column, there is a reduced pressure (vacuum), which causes suction, lifting up everything that is encountered on the way (earth, sand, water, sometimes very heavy objects). The height of the sleeve can reach 800 – 1500 meters, the diameter – from several tens above water to hundreds of meters above land. The length of the path of a tornado ranges from several hundred meters to tens of kilometers (40 – 60 km.). The tornado spreads, following the terrain, the speed of the tornado is 50-60 km/h.

A tornado occurs in a thundercloud (in the upper part it has a funnel-shaped extension that merges with the clouds) saturated with charged ions and then spreads in the form of a dark sleeve or trunk towards the land or sea surface. When the tornado descends to the surface of the earth or water, its lower part also becomes expanded, similar to an overturned funnel. Tornadoes occur both above the water surface and over land, much more often than hurricanes, usually in the warm sector of the cyclone, more often before the cold front. Its formation is associated with a particularly strong instability of the regular distribution of atmospheric air temperatures over height (atmospheric stratification). It is often accompanied by thunderstorms, rain, hail, and a sharp increase in wind.

Tornadoes are observed in all regions of the globe. Most often they occur in Australia, Northeast Africa, the most common in America (USA), in the warm sector of the cyclone before the cold front. The tornado moves in the same direction as the cyclone. There are more than 900 of them a year, and most of them originate and cause the most damage in Tornado Valley.

Tornado Valley stretches from West Texas to the Dakotas 100 miles north to south and 60 miles east to west. Warm, moist air from the north of the Gulf of Mexico meets dry, cold winds from the south from Canada. Huge clusters of thunderclouds begin to form. The air rises sharply inside the clouds, cools down there and descends. These streams collide and rotate relative to each other. There is a thunderstorm cyclone in which a tornado is born.

Tornado classification

Bice-like – this is the most common type of tornadoes. The funnel looks smooth, thin, and can be quite tortuous. The length of the funnel considerably exceeds its radius. Weak whirlwinds and whirlpools that descend on the water are, as a rule, whip-like whirlwinds.

Blurry – look like shaggy, rotating clouds reaching the ground. Sometimes the diameter of such a tornado even exceeds its height. All craters of large diameter (more than 0.5 km) are indistinct. Usually these are very powerful whirlwinds, often compound ones. They cause enormous damage due to their large size and very high wind speeds.

Composite – a composite tornado in Dallas 1957. May consist of two or more separate blood clots around the main central tornado. Such tornadoes can be of almost any power, however, most often they are very powerful tornadoes. They cause significant damage over vast areas. Most often formed on the water. These funnels are somewhat related to each other, but there are exceptions.

Fire tornadoes are ordinary tornadoes generated by a cloud formed as a result of a strong fire or volcanic eruption. It is these tornadoes that were first artificially created by man (the experiments of J. Dessen (Dessens, 1962) in the Sahara, which continued in 1960-1962). “Absorb” the tongues of flame, which are drawn to the parent cloud, forming a fiery tornado. It can spread a fire for tens of kilometers. They are whip-like. Cannot be vague (the fire is not under pressure like whip-like tornadoes).

Water tornadoes are tornadoes that formed above the surface of the oceans, seas, in the rare case of lakes. They “absorb” waves and water into themselves, forming, in some cases, whirlpools that stretch towards the parent cloud, forming a water tornado. They are whip-like. Like fire tornadoes, they cannot be vague (the water is not under pressure, as in whip-like tornadoes).

Earth tornadoes – these tornadoes are very rare, they form during destructive cataclysms or landslides, sometimes earthquakes above 7 points on the Richter scale, very high pressure drops, the air is very rarefied. A whip-like tornado is located “carrot” (thick part) to the ground, inside a dense funnel, a thin trickle of earth inside, a “second shell” of earthen slurry (if a landslide). In the case of earthquakes, it lifts stones, which is very dangerous.

Snowstorms are snow tornadoes during a heavy snowstorm.

Rice. A tornado and a cavitation cord behind a radial-axial turbine and the distribution of velocity and pressure in the cross sections of these vortex formations.

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