Wind information

1, natural interpretation

Wind wind

Usually refers to the horizontal motion component of air, including direction and magnitude, that is, wind direction and wind speed. But for flight, it also includes vertical motion components, so-called vertical or ascending and descending airflow. Gust (also known as gust) is the wind whose wind speed changes dramatically in a short time. Meteorological wind direction refers to the direction of the wind, and navigational wind direction refers to the direction of the wind. In meteorological service, the grade of wind is often used to indicate the size of wind speed. The "Beaufort Wind Scale" drawn up by Englishman F Beaufort in 1805 divides the wind power into 13 (0 ~ 12). From 1946, the wind level increased to 18 (0 ~ 17). Wind and gust have a great influence on aircraft flight. When taking off and landing, you must choose the appropriate direction according to the wind direction and wind speed on the ground; In flight, the drift must be corrected in time according to the wind direction and speed, so as to maintain a certain course and calculate the standard flight time. When building an airport, the runway direction must be determined according to the climatic data of the wind. In addition, the wind also has a great influence on the flight performance of aircraft. For example, when the plane flies against the wind, the lift of the plane will increase. Gust has a great influence on the flight load of aircraft, so it is necessary to give a model and strength standard to describe gust in aircraft design.

Definition of wind

The movement of air relative to the ground usually refers to its horizontal component, which is expressed by wind direction, wind speed or wind force. Wind direction refers to the direction of airflow, which is often recorded in the direction of 16. Wind speed is the horizontal distance that air moves in unit time, in meters per second. The horizontal wind speed in the atmosphere is generally 1.0 ~ 10 m/s, typhoons and tornadoes can sometimes reach 102 m/s, and the wind speed in farmland can be less than 0. 1 m/s. There are two kinds of observation data of wind speed: instantaneous value and average value, and the average value is generally adopted. Wind is measured by electric anemometer, portable anemometer, Dyne anemometer and hot ball anemometer, which is used to measure the breeze in farmland. It can also be estimated according to the wind level and the signs of ground objects.

The cause of wind

The direct cause of the wind is the uneven distribution of air pressure in the horizontal direction. Wind is comprehensively influenced by different factors such as atmospheric circulation, topography and water area, and its manifestations are various, such as monsoon, local sea-land wind, valley wind and foehn wind. Simply put, wind is the movement of air molecules. To understand the causes of wind, we must first understand two key concepts: air and air pressure. The components of air include nitrogen molecules (accounting for 78% of the total air volume), oxygen molecules (accounting for about 2 1%), water vapor and other trace components. All air molecules are moving at a very fast speed, colliding with each other and anything on the horizon.

Air pressure can be defined as the pressure exerted by air molecules in a given area. Generally speaking, the more air molecules exist in an area, the greater the air pressure in this area. Accordingly, wind is the result of pressure gradient force.

However, some changes in atmospheric pressure are caused by storms, some by uneven surface heating, and some by atmospheric molecules being forced to flow from a relatively high pressure area to a low pressure area in a certain horizontal area.

Most of the high-pressure and low-pressure belts shown on the weather map only form a mild breeze that accompanies us. However, the pressure difference required to generate the breeze only accounts for 1% of the atmospheric pressure itself, and this pressure change will occur in many areas. Relatively speaking, the formation of strong storms stems from the change of larger and more concentrated pressure areas.

The influence of the wind

Wind is one of the environmental factors of agricultural production. Moderate wind speed plays an important role in improving farmland environmental conditions. The increase of wind speed accelerates or strengthens the surface heat exchange, evapotranspiration of farmland and the transportation of carbon dioxide and oxygen in the air. Wind can spread plant pollen and seeds and help plants pollinate and reproduce. Wind energy is widely distributed and inexhaustible. Monsoon prevails in China, which is beneficial to the growth of crops. The Inner Mongolia Plateau, the Northeast Plateau, the southeast coast and the inland mountainous areas are rich in wind energy resources, which can be used as energy development and utilization.

Wind will also have a negative impact on agriculture. It can spread pathogens and plant diseases. High-altitude wind is a meteorological condition for the long-distance migration of pests such as armyworm, rice planthopper, rice leaf roller and locust. Strong wind causes mechanical wear of leaves, lodging of crops, broken trees, falling flowers and fruits, which affects the yield. Strong winds can also lead to soil erosion and sand dune movement, and destroy farmland. Blindly reclaiming wasteland in arid areas, wind will lead to land desertification. Strong winds and snowstorms in pastoral areas will disperse herds and aggravate freezing damage. Some special properties of local winds often cause wind disasters. Tidal wind with high salinity, scorching wind with high temperature and low temperature, and dry-hot wind blowing from the sea have seriously affected the flowering and fruiting of fruit trees and the filling of cereal crops. In order to prevent wind damage, wind-resistant varieties with dwarfing, lodging resistance and friction resistance are usually cultivated. It is more effective to build windbreaks and set up windbreaks.

wind energy

The kinetic energy formed by air flow is extremely wind energy. Wind energy is a conversion form of solar energy.

The radiation of the sun causes uneven heating of the earth's surface, uneven distribution of atmospheric pressure, and the air moves along the horizontal direction to form wind. The formation of wind is the result of air flow. The formation of wind energy utilization is mainly to convert the kinetic energy of atmospheric movement into other forms of energy.

In the equatorial and low latitudes, the solar altitude angle is large, the sunshine time is long, the solar radiation intensity is strong, the ground and atmosphere receive more heat and the temperature is high; At higher latitudes, the solar altitude angle is small, the sunshine time is short, the heat received by the ground and the atmosphere is less, and the temperature is low. This temperature difference between high latitude and low latitude forms a north-south pressure gradient, which makes the air move horizontally and the wind blows along the direction of the horizontal pressure gradient, that is, the vertical and isobars blow from high pressure to low pressure. The earth is spinning, and the force that deflects the horizontal movement of air is called geostrophic deflection force, which deflects the airflow in the northern hemisphere to the right and the airflow in the southern hemisphere to the right, so the atmospheric movement of the earth is not only affected by the pressure gradient force, but also by geostrophic deflection. The real motion of the atmosphere is the result of the comprehensive influence of these two forces.

In fact, the sea surface wind is not only dominated by these two forces, but also influenced by the ocean and topography to a great extent. Mountain passes and straits can change the direction of airflow and increase the wind speed, while the friction between hills and mountains reduces the wind speed, while isolated peaks increase the wind speed because of high altitude. Therefore, the temporal and spatial distribution of wind direction and wind speed is more complicated.

In winter, the mainland is colder than the ocean, and the pressure on the mainland is higher than the ocean. The wind blows from the mainland to the sea. In summer, on the other hand, the mainland is hotter than the ocean, and the wind blows inland from the ocean. This seasonal wind is called monsoon. The so-called land-sea breeze is that during the day, the air flow on the mainland is heated and expanded, rises to high altitude and flows to the ocean, and then cools and sinks over the ocean. The air flow near the surface of the ocean blows to the mainland to compensate for the rising air flow from the mainland. The low-level wind blows from the ocean to the mainland, which is called sea breeze. At night (winter), on the other hand, the low-level wind blows from the mainland to the ocean, which is called land wind. In mountainous areas, due to thermal reasons, it blows from the valley to the plain or hillside during the day and from the plain or hillside at night. The former is called valley wind and the latter is called mountain wind. This is because the hillside heats up quickly during the day, and the temperature is higher than the air temperature at the same height above the valley. The warm air on the hillside flows from the hillside to the valley, and the air in the valley supplements the air lost along the hillside. At this time, the wind blowing from the valley to the hillside is called valley wind. At night, the hillside is cooled by radiation, which is faster than the air at the same height. Cold air flows into the valley along the hillside, which is called mountain wind. When solar radiation can pass through the earth's atmosphere, the energy absorbed by the atmosphere is about 2 * 10 16W, and a small part of it is converted into kinetic energy of air. Because the tropics absorb more solar radiation energy than the polar regions, the atmospheric pressure difference leads to airflow and "wind". As for local areas, such as high mountains and deep valleys, the air at the top of the mountain is heated up by sunlight during the day, and the cold air in the deep valleys takes its place, so the wind blows from the deep valleys to the mountains; At night, the air on the mountain dissipates quickly, so the wind blows from the mountain to the deep valley. For another example, in coastal areas, due to the temperature difference between land and ocean during the day, sea breeze blows to land; On the contrary, the land wind blows to the sea at night.

Classification of wind

According to the phenomenon caused by the wind to the ground objects, the wind force is divided into 13 grades, which are called wind grades, and recorded by numbers of 0 ~ 12 grades.

wind scale

Wind grade and symbol name Wind speed (m) * Sea surface wave height of land image (m)

0 No wind, 0.0-0.2 smoke, straight up, calm, 0.0

1 soft wind 0.3- 1.5 smoke indicates that the wind direction is at the peak of microwave 0. 1 and there is no water drop.

2 breeze 1.6-3.3 Feel the wind, and the small wave crest will not be broken by 0.2.

3 breeze 3.4-5.4 standard propagation wavelet peak rupture 0.6

4 breeze 5.5-7.9 blows dust, small waves, foam peak 1.0.

5 Strong breeze 8.0- 10.7 Waves and foam peaks in swaying young trees 2.0

6 strong wind 10.8- 13.8 wire sound waves to water droplets 3.0

7 gale 13.9- 17. 1 difficulty in walking, peak breaking, foam strips 4.0

8 strong wind 17.2-20.7 damaged branches, wave 5.5.

9-level gale 20.8-24.4 Small damaged houses wave crest rollback 7.0

10 gale 24.5-28.4 uprooting trees, waves rolling and roaring 9.0

1 1 Storm 28.5-32.6 was generally damaged, and the peaks were all in water droplets 1 1.5.

12 hurricane 32.7- destructive wave +04.0

Note: The wind speed listed in this table refers to the wind speed value at10m above the flat ground.

2. Dictionary definition

wind

Initial: f

Prefix: wind, (,wind,)

Four numbers: 3500

Athena Chu: Damn it.

Stroke: 04 painting

Radical painting: 04

Radical: wind system

Interpretation: 1 Air flow phenomenon caused by uneven air pressure distribution: north ~| blowing ~| tornado ~

2. blown by the wind: ~ dry | dry ~ clean.

3. Blown dry: ~ chicken | ~ meat.

4. As fast and common as the wind: ~ Go | ~ Go.

5. Customs: ~ Qi | ~ Customs | Change ~ | Change ~ Customs.

6. scenery: ~ light | ~ scenery.

7. Etiquette; Attitude; Attitude: ~ Adoption | ~ Degree | ~ Style | Learning || Work ~

8. news; Rumor: ~ sound | mouth | son | spread | smell | smell ~ and move.

9. Legend; Groundless: ~ spread | ~ smell | ~ talk ~ language.

10. Situation; Momentum: look ~ turn | look ~ invincible.

1 1. refers to the folk song: Cai ~.

12. Chinese medicine refers to some diseases: ~ cold | ~ wet | moderate ~ | epilepsy ~ | goose's feet ~.

Wind, eight winds also. In the east, the wind is clear and the gas is positive; Southeast wind, the wind is clear and the gas is positive; In the south, there is a scenery; In the southwest, there is a cool wind; In the west, there is a bad wind; In the north, there is a broad wind of Mo; In the northeast, there is a melting wind. Wind-driven insects are born, so the insects turn into eight days. -"Shuo Wen"

The beginning of spring style. -"Yi Tong Guayan"

Northeast wind. -"Guangya Shi Tian"

From the 45th day of the solstice winter, there was wind. -Huainanzi Astronomy

The wind lives in the northeast dimension, and everything is the master. Words exclude everything. -"Historical Records and Calligraphy"

Is there no wind today? -"Yin Ruins Literati"

Have it both ways, there's nothing to avoid. -biography of Han Shu, Zhao, Han Yin and Zhang Wang.

There is wind in the cloud flight. -Liu Bang's Song of the Wind

Rain is coming and the wind is getting stronger and stronger. -Xu Hun's "East Building of Xianyang City"

Another example: strong wind (violent wind); Wind signal (magnitude and direction of wind); The wind mass (cyclone) is a metaphor for fast speed); The wind blows in the sun; Wind hail (wind hail); Wind (wind disaster and flood); Wind (snow)

Customs; "generalmood customization"

Today, it is difficult to change the customs. -"Purple Tongzhi Sword"

Traitors scattered, customs changed greatly. -biography of Han Shu, Zhao, Han Yin and Zhang Wang.

Therefore, it is necessary to observe the folk customs. -Liu Tang Zongyuan's Snake Catcher

Change customs. -Xunzi's Theory of Music

Another example: the beauty of the wind (the beauty of customs); Kaze Jun (simple folk customs); Decline of wind (customs); Custom; Wind drift (custom drift)

Style, bearing and charm

I also tasted the legacy of the elderly. -Han Sima Qian's "Reporting Ren An"

Another example: the wind bureau (style, appearance); Anemometer (style instrument); Wind governance (demeanor); Wind cutting (style, orientation); Wind period (bearing, mind); Wind festival (bearing feelings)

Style characteristics of literary and artistic works [way; Style [1]. For example, Fengshen (refers to the style and charm of literary and artistic works); Wind emblem (style and charm of the article)

Wind, news [news; Information]

But knowing the wind has a reward of 120. -"Surprise moment"

Another example: the wind police (the wind is very tight); Wind disaster (wind; Message); Wind (wind); Wind path (wind, clue); Act immediately after hearing the news ―― answer the phone immediately.

One of the six meanings of The Book of Songs. It refers to one of the three types of poetry in The Book of Songs, that is, the folk song "Ballad" included in Guofeng.

The wind picks flies and apples. -"Zuo zhuan, three years of seclusion"

Happy to fuck the local style and never forget the old feelings. -"Zuo Zhuan became a public for nine years"

Another example is: Feng Fu (referring to Feng He Fu in the six meanings of The Book of Songs); The wind is wandering (the poet's sorrow)

Love between men and women [love]

Now that he has grown up, he begins to understand romance, and he is attracted by Qin Zhong's romantic personality. -A Dream of Red Mansions

Another example: romance (referring to the love between men and women); The wind and the moon are always new (referring to everlasting love); Romantic children (children addicted to romantic fields)

Discipline, education [[〖conductanddiscipline〗] such as: wind benefit (enlightenment); Fengchi (describing Dehua as widely circulated); Wind love (wind ze Dehua); Style (teaching should be harmonious); Wind strategy (discipline and strategy); Wind politics (political education)

Power [power]. For example, wind sweeping (described as strong as strong wind sweeping); A horse in battle formation (a ship in the wind, a horse in battle formation). Strong metaphor)

One of the six evils. Madness, also known as madness. Later it was called "disease" [[epilepsy]. Such as: wind vertigo (epilepsy); Wind mania (madness and dementia)

3. Medical interpretation

The concept of TCM etiology, also known as wind evil. Wind evil has external and internal causes. External wind is a kind of climate or environmental state formed by air flow in nature. It is the main gas in spring and belongs to one of the six qi (see Qi). However, this kind of climate or environmental state will make people who are weak in vital qi or susceptible to constitution get sick. For these people, external wind becomes a pathogenic factor and belongs to one of the six evils. Internal wind refers to the pathological state caused by excessive yang in the body caused by various reasons, which is closely related to the pathological changes of the liver. Although there are differences between external wind and internal wind, they all have the characteristics of rapid onset and diverse changes in clinic.

Although wind is the main gas in spring, it exists in four seasons, so the diseases caused by external wind are not seasonal; Pathogens such as cold, dampness, dryness, and heat (fire) often attach to the wind and invade the human body, or the wind and phlegm-dampness in the body combine to cause disease. Such as exogenous wind-cold, wind-heat, rheumatism, wind-cold-dampness arthralgia, etc. Therefore, exogenous wind is often the forerunner of exogenous pathogenic factors and the main pathogenic factor of six evils, so there is a saying that "wind is the beginning of all diseases" and "wind is the length of all diseases". Exterior wind belongs to yang evil, which is light in nature and has the characteristics of ascending, ascending and external. Therefore, it often hurts the upper part of the human body (head and face), yang meridian and muscle surface, making the fur loose, causing headache, sweating and bad wind. External wind also has the characteristics of good behavior, so the disease site moves around after illness, and there is no fixed activity place. For example, wind arthralgia (walking arthralgia) is manifested as wandering joint pain; Rubella comes quickly and itches painfully, but sometimes it goes quickly and often leaves no trace after fading. There are many diseases and syndromes caused by exogenous wind, so it is necessary to determine the invaded human body parts and other pathogens (or properties) according to their symptoms and signs. Clinically, the most common disease is that exogenous wind-cold or heat-toxic wind invades human lung health, resulting in fever, headache, aversion to cold, cough and other symptoms, commonly known as colds. The syndrome and treatment of exogenous wind evil is always based on expelling wind, and other evil spirits are also treated, such as wind-cold cold with pungent temperature and wind-heat with pungent cold.

Internal wind is mostly caused by liver dysfunction, so it is also called liver wind moving internally. Different from the syndromes caused by external wind, the pathological state caused by internal wind can appear dizziness, convulsion, spasm, trembling, peristalsis, mouth and eyes in clinic. Oblique, even the symptoms of abnormal limb movements such as varus angle arch and stiff neck were compared by the ancients. There are many reasons for endogenous wind syndrome, including liver-yang transforming into wind, extreme heat generating wind, yin deficiency generating wind and blood deficiency generating wind, which leads to hyperactivity of yang in the body. Liver yang turns to wind, mostly due to emotional exhaustion, improper diet, excessive drinking and so on. , leading to liver depression into fire, or water containing no wood, liver yang hyperactivity, yin not controlling yang, liver yang hyperactivity into wind, rising to the top or pulse, resulting in death, unconsciousness, also known as "stroke" (roughly the same as cerebrovascular disease in western medicine), extremely hot wind mostly occurs in the extreme period of acute fever. Due to excessive heat pathogen, burning liver meridian and excessive yang heat, dizziness, convulsion and other symptoms appear. Wind movement due to yin deficiency is more common in the late stage of fever, or after severe sweating, vomiting and diarrhea. At this time, the vaginal fluid is exhausted, and the liver-governing meridians are not nourished, and muscle contracture can be seen clinically. Diseases such as hand and foot peristalsis. Blood deficiency leads to wind, which is mostly caused by insufficient hematopoiesis or excessive blood loss, insufficient blood stored in liver, dystrophy of tendons and veins, and internal movement of deficiency wind. Clinically, symptoms such as numbness of limbs, muscle twitching and even limb contracture can be seen. The diagnosis of endogenous wind syndrome should be based on their respective clinical symptoms and signs. Treatment should focus on their respective causes, such as calming the liver and calming the wind for those with liver yang, clearing away heat and calming the wind for those with extreme heat, nourishing yin and calming the wind for those with wind due to yin deficiency, and nourishing blood and calming the wind for those with wind due to blood deficiency.

4. Music album

Special edition: wind

Singer: Steven Liu.

Language: Mandarin

Company: Tony

Date: 1979.00.00

wind

[02] Spray

What you said.

I found myself.

first glimmerings of dawn

[06] Memories of Wild Ginger Flower

[07] Leaves send acacia.

[08] Tropical fish

[09] Eagle

[10] that day

Affectionate money

[12] White wooden house

The cause of wind

[design]

Wind is the horizontal flow of air caused by temperature difference and air pressure difference. In order to let students know the cause of wind, we can use the method of simulation experiment: lighting candles in the convection box as a heat source, so that there is a certain temperature difference between the air inside and outside the box, the air inside the box becomes lighter when heated, and the pressure decreases when it is discharged from the upper air hole, so that the cold air outside the box flows into the box from the air inlet. In order to let students observe the air flow, cigarettes can be used.

[equipment]

Air convection box, short candles, matches, incense (or moxa used for acupuncture in traditional Chinese medicine).

[Step]

1. Observe the structure of the air convection box first (glass is installed on one side of the box for easy observation).

2. Without lighting the candles in the box, put the lit incense (or wormwood) next to the air inlet on the side of the convection box, and you can observe that the smoke rises upward and rarely flows into the box.

3. Light the candle in the box, close the lid, and then put the lit incense (or wormwood) at the air inlet on the side, and you will see the smoke flow into the box from the air inlet and then flow out from the air inlet above.

4. Put out the candles in the box, close the box cover, and put the lit incense (or wormwood) at the side air inlet later to prevent the smoke from flowing into the box.

[attention]

The convection box is sealed as airtight as possible, and the experimental effect is obvious.

Edit entry

Open classification:

Science, nature, meteorology

References:

1. Global Science Magazine "Handbook for Primary School Science Teachers" (Biology and Nature Room of People's Education Press)

salute

tornado

First of all, nature

Tornado (tornado)

Tornado is a kind of vortex: the air rotates rapidly around the axis of tornado and is attracted by the extremely low air pressure in the center of tornado. In the thin layer of air tens of meters thick near the ground, the airflow is sucked into the bottom of the vortex from all directions. Then it becomes a vortex around the axis. The wind in a tornado is always cyclonic, and the air pressure in its center can be 10% lower than that around it.

A tornado is a strong wind vortex accompanied by a funnel-shaped cloud column rotating at high speed. The wind speed near the tornado center can reach 100 m/s to 200 m/s, with a maximum of 300 m/s, which is several times larger than the maximum wind speed near the typhoon center. The central air pressure is very low, generally as low as 400 hectopascals and as low as 200 hectopascals. It has a great sucking effect, which can suck the sea (lake) water away from the sea (lake) surface and form a water column. Because the air inside the tornado is extremely thin, the temperature drops sharply and the water vapor condenses rapidly, which is an important reason for the formation of funnel cloud column. The average diameter of the funnel cloud column is only about 250 meters. Tornadoes are produced in very unstable cumulonimbus clouds. Its formation is related to the strong rise of warm and humid air, the southward movement of cold air and topography. Its life history is short, usually lasting ten minutes to an hour or two, but its destructive power is amazing. It can uproot trees, blow down buildings or roll some ground objects into the air. There are tornadoes in Jiangsu Province almost every year, but the location has no obvious regularity. It usually appears in June and July, sometimes in early or middle August.

Tornado formation

Tornadoes are the product of thunderstorms in the clouds. Specifically, a tornado is a form in which a small part of the huge energy of a thunderstorm is released in a small area. The formation of tornadoes can be divided into four stages:

(1) The instability of the atmosphere produces a strong updraft, which is further strengthened due to the influence of the maximum transit airflow in the rapids.

(2) Due to the interaction with the wind with shear speed and direction in the vertical direction, the updraft starts to rotate in the middle of the troposphere, forming a mesoscale cyclone.

(3) With the development and upward extension of mesoscale cyclone to the ground, it becomes thinner and stronger. At the same time, a small area to strengthen cooperation, that is, the primary tornado is formed inside the cyclone, and the same process of producing the cyclone forms the tornado core.

(4) The rotation in the tornado core is different from that in the cyclone, and its intensity is enough to make the tornado extend to the ground. When the developing vortex reaches the ground, the ground air pressure drops sharply and the ground wind speed rises sharply, forming a tornado.

Tornadoes often occur in thunderstorm weather in summer, especially in the afternoon to evening. The attack range is small, and the diameter of tornadoes is generally between ten meters and several hundred meters. The survival time of tornadoes is generally only a few minutes, and the longest is no more than a few hours. The wind is particularly strong, and the wind speed near the center can reach 100-200m/s, which is extremely destructive. Where tornadoes pass, trees are often pulled up, vehicles are overturned, buildings are destroyed, and sometimes people are sucked away, which is very harmful.

Precautionary measures for tornadoes

(1) At home, be sure to stay away from doors, windows and external walls of houses and hide in the wall or small room opposite the tornado. The safest place to avoid a tornado is the basement or semi-basement.

(2) In case of emergency such as pole collapse and house collapse, the power supply should be cut off in time to prevent electric shock or fire.

(3) When there is a tornado outside the venue, you should look for low-lying land nearby, but stay away from trees and telephone poles to avoid being smashed, crushed and electrocuted.

(4) When the car encounters a tornado when going out, you must not drive to avoid it, nor do you avoid it in the car, because the car has almost no defense ability against tornadoes. You should leave the car immediately and avoid it in a low-lying place.

1On May 27th, 999, four counties in central Texas, including Austin, the capital, were hit by a huge tornado, killing at least 32 people and injuring dozens. It is reported that in jarrell, 40 miles north of Austin, more than 50 houses collapsed and more than 30 people were killed in the tornado. The damaged area is 1 mile long and 200 yards wide. This is another tornado area in the United States after Miami was hit by a tornado on May 3, 65438.

Generally speaking, a tornado is a whirlwind. When it touches the ground, its diameter ranges from several meters to 1 km, with an average of several hundred meters. Tornadoes range from a few meters to dozens of kilometers, and things are robbed everywhere. The funnel-shaped center of tornado is composed of inhaled dust and condensed water vapor, which is a visible "dragon mouth". On the ocean, especially in the tropics, similar scenes are called sea tornadoes.

Most tornadoes rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere, with some exceptions. The exact mechanism of tornado formation is still under study, and it is generally believed to be related to the violent activities of the atmosphere.

Since19th century, the accuracy of weather forecast has been greatly improved, and various disasters and storms such as tornadoes and hurricanes can be detected by weather radar.

1995 In a tornado in Admore, Oklahoma, USA, heavy objects such as roofs were blown dozens of miles away. Most of the debris falls on the left side of the tornado passage, and there are often obvious landing areas according to the weight. Lighter debris may fly more than 300 kilometers before landing.

The tornado struck suddenly and violently, and the wind force produced was the strongest on the ground. In the United States, the number of deaths caused by tornadoes is second only to lightning every year. Its damage to buildings is also quite serious, often devastating.

Under the attack of a strong tornado, the roof of the house will fly like a glider. Once the roof is swept away, the rest of the house will collapse. Therefore, if we can strengthen the stability of the roof when building houses, it will help to prevent the tornado from causing huge losses when crossing the border.

Tornadoes are usually extremely fast. It is not surprising that the wind speed is 100 m per second, even reaching more than 175 m per second, which is five or six times larger than the typhoon 12. The range of wind is very small, generally the diameter is only 25~ 100 meters, and only in rare cases can the diameter reach more than one kilometer; It takes only a few minutes from occurrence to disappearance, at most a few hours.

Tornadoes are also very powerful. On September 24th, 1956, a tornado appeared in Shanghai. It easily lifted a large oil storage barrel weighing 220,000 Jin to the altitude of15m, and then threw it away from120m.

Tornadoes, also known as cyclones in America, are common natural phenomena. Cyclones are often more destructive than earthquakes.

1879 at 4 pm on may 30, two dark and thick clouds were merging over northern Kansas. After 15 minutes, a vortex was generated at the lower end of the cloud. The vortex has grown rapidly and become a huge pillar of indomitable spirit. Within three hours, it ran wild all over the state like a dragon, and no one was spared wherever it went. However, the strangest thing happened at the beginning, when the tornado whirled across a small river and met a cliff. Obviously, it is impossible to surpass this obstacle, so the vortex turns to the west, and there happens to be a newly built 75-meter-long railway bridge over there. The tornado vortex actually pulled it down from the stone pier, twisted it a few times, and then threw it into the water.

Tornado detection

Tornadoes have long been a mystery, and it is for this reason that it is necessary to understand them. The tornado struck suddenly and violently, and the wind force produced was the strongest on the ground. Because of its suddenness and dispersion, it is difficult to observe it effectively.

What is the wind speed of a tornado? No one really knows, because the time from the occurrence to the dissipation of tornadoes is very short and the area of action is very small, so that the existing detection instruments are not sensitive enough to accurately observe tornadoes. Relatively speaking, Doppler radar is an effective and commonly used observation instrument. Doppler radar aims at the microwave beam emitted by the tornado, and the microwave signal is reflected by the debris and raindrops in the tornado and then received by the radar. If the tornado is far away from the radar, the frequency of the reflected microwave signal will move to the low frequency direction; On the contrary, if the tornado gets closer and closer to the radar, the reflected signal will move to the high frequency direction. This phenomenon is called Doppler frequency shift. After receiving the signal, the radar operator can calculate the speed and moving direction of the tornado by analyzing the frequency shift data.

The danger of tornadoes.

1995 In a tornado in Admore, Oklahoma, USA, heavy objects such as roofs were blown dozens of miles away. Most of the debris falls on the left side of the tornado passage, and there are often obvious landing areas according to the weight. Lighter debris may fly more than 300 kilometers before landing.

The tornado struck suddenly and violently, and the wind force produced was the strongest on the ground. In the United States, the number of deaths caused by tornadoes is second only to lightning every year. Its damage to buildings is also quite serious, often devastating.

Under the attack of a strong tornado, the roof of the house will fly like a glider. Once the roof is swept away, the rest of the house will collapse. Therefore, if we can strengthen the stability of the roof when building houses, it will help to prevent the tornado from causing huge losses when crossing the border.

Dragon absorbs water: another name for tornado. Tornado got its name because it is very similar to the East China Sea Horned Dragon in breaking the waves in ancient mythology. It also has many aliases, such as "dragon absorbs water", "dragon wags its tail" and "upside down dragon".

Characteristics of tornadoes

Tornadoes often occur in thunderstorm weather in summer, especially in the afternoon to evening. The attack range is small, and the diameter of tornadoes is generally between ten meters and several hundred meters. The survival time of tornadoes is generally only a few minutes, and the longest is no more than a few hours. The wind is particularly strong, and the wind speed near the center can reach 100-200m/s, which is extremely destructive. Where tornadoes pass, trees are often pulled up, vehicles are overturned, buildings are destroyed, and sometimes people are sucked away, which is very harmful.

Precautionary measures for tornadoes

(1) At home, be sure to stay away from doors, windows and external walls of houses and hide in the wall or small room opposite the tornado. The safest place to avoid a tornado is the basement or semi-basement.

(2) In case of emergency such as pole collapse and house collapse, the power supply should be cut off in time to prevent electric shock or fire.

(3) When there is a tornado outside the venue, you should look for low-lying land nearby, but stay away from trees and telephone poles to avoid being smashed, crushed and electrocuted.

(4) When the car encounters a tornado when going out, you must not drive to avoid it, nor do you avoid it in the car, because the car has almost no defense ability against tornadoes. You should leave the car immediately and avoid it in a low-lying place.

1On May 27th, 999, four counties in central Texas, including Austin, the capital, were hit by a huge tornado, killing at least 32 people and injuring dozens. It is reported that in jarrell, 40 miles north of Austin, more than 50 houses collapsed and more than 30 people were killed in the tornado. The damaged area is 1 mile long and 200 yards wide. This is another tornado area in the United States after Miami was hit by a tornado on May 3, 65438.

Generally speaking, a tornado is a whirlwind. When it touches the ground, its diameter ranges from several meters to 1 km, with an average of several hundred meters. Tornadoes range from a few meters to dozens of kilometers, and things are robbed everywhere. The funnel-shaped center of tornado is composed of inhaled dust and condensed water vapor, which is a visible "dragon mouth". On the ocean, especially in the tropics, similar scenes are called sea tornadoes.

Most tornadoes rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere, with some exceptions. The exact mechanism of tornado formation is still under study, and it is generally believed to be related to the violent activities of the atmosphere.

Since19th century, the accuracy of weather forecast has been greatly improved, and it can be monitored by weather radar.