Typhoon and hurricane are both a kind of wind, but they happen in different places and have different names. The typhoon is in the western part of the North Pacific Ocean, west of the international date, including the South China Sea; Tropical cyclones in the Atlantic Ocean or the eastern North Pacific Ocean are called hurricanes, which means hurricanes in the United States and typhoons in the Philippines, China and Japan.

Typhoon is a strong tropical cyclone generated on the surface of tropical ocean. Typhoons are often accompanied by strong winds and heavy rains. The wind rotates counterclockwise. Isobars and isotherms are approximately a set of concentric circles. The central air pressure is the lowest and the temperature is the highest.

Typhoon classification

Typhoons are classified according to the maximum wind force near the center of tropical cyclones. In the past, the meteorological department of our country called the winds with the magnitude of 8 to 1 1 as typhoons, and the winds with the magnitude of 12 or above as strong typhoons. From 65438+65438+ 1 in 0989 to 65438+1in October, it is called a tropical storm when the maximum wind force near the center is 8 ~ 9, and it is called a strong tropical storm when10 ~1. In 2006, according to the notice of National Standard for Tropical Cyclone Grades (GBT 1920 1-2006) issued by China Meteorological Bureau, tropical cyclones were divided into six grades according to the maximum surface wind speed near the center: when the maximum wind force near the center is 16 or above, it is called super typhoon, and the maximum wind force near the center is/KLOC-. The maximum wind force near the center 12- 13 is called typhoon, l0- 1 1 is called strong tropical storm, 8-9 is called tropical storm, and 12- 13 is called tropical storm. For the sake of simplicity, the following is still collectively referred to as typhoon.

typhoon track

Typhoon paths can be roughly divided into three categories: ① Westward typhoons move from the east to the west of the Philippines, cross the South China Sea, and finally land on Hainan Island in China or northern Vietnam. (2) Landing type: The typhoon moved to the northwest, crossed the Taiwan Province Strait, landed in the coastal areas of Guangdong, Fujian and Zhejiang, and gradually weakened into a low pressure. This typhoon has the greatest impact on China. The two typhoons "90 15" and "97 1 1" which have had the greatest impact on Jiangsu in recent years belong to this type. (3) Parabolic type: The typhoon moves to the northwest first, then turns to the northeast when approaching the eastern coast of China, and turns to the vicinity of Japan, with a parabolic path. Typhoon disaster. Typhoon is a very destructive and disastrous weather system, but sometimes it can also play a beneficial role in eliminating drought. Its harmfulness mainly includes three aspects: ① strong wind. The maximum wind force near the typhoon center is generally above 8. ② Heavy rain. Typhoon is one of the strongest rainstorm weather systems. Generally, it can produce rainfall of150 mm ~ 1 000 mm in the area where typhoons pass, and a few typhoons can produce heavy rain above1000 mm. The torrential rain caused by Typhoon No.3 in the upper reaches of Huaihe River 1975 created the extreme value of heavy rain in Chinese mainland and caused the "75.8" flood in Henan. ③ Storm surge. Generally, typhoons will increase water in coastal waters, and the maximum water increase in coastal areas of Jiangsu Province can reach 3m. Typhoons "9608" and "97 1 1" increased the water, which made Jiangsu's coastal areas along the Yangtze River appear unprecedented.

After the typhoon is formed, it will generally move out of the source and experience the evolution process of development, weakening and extinction. A mature typhoon has a circular vortex radius of 5 OOKM ~ 1000 km and a height of 15 km ~ 20 km. Typhoon consists of three parts: peripheral area, maximum wind speed area and typhoon eye. The wind speed in the peripheral area increases from outside to inside, with spiral clouds and precipitation; The strongest precipitation occurs in the maximum wind speed area, with an average width of 8 km ~ 19 km, and there is a circular cloud wall between it and the typhoon eye; The typhoon eye is located in the center of the typhoon. The most common typhoon eye is round or oval, ranging in diameter from 10 km to 70 km, with an average of about 45km. The weather in typhoon eye is calm, partly cloudy, dry and warm.

Number of typhoons

China numbered the tropical depressions that entered the west of l50 degrees east longitude and the north of l0 degrees north latitude. The winds near the center were strong and reached magnitude 8, which were arranged in the order of annual occurrence. This is the "Typhoon X this year (tropical storm, strong tropical storm)" that we heard or saw on radio and television.

The number of typhoons is also the number of tropical cyclones. People want to number tropical cyclones, on the one hand, because a tropical cyclone often lasts for more than a week, and several tropical cyclones may appear in the ocean at the same time. With the serial number, there will be no confusion; On the other hand, it is due to the naming, definition, classification method and determination of the center position of tropical cyclones. ......

Why do typhoons, hurricanes and tornadoes form?

Typhoon is a tropical storm, usually formed in the tropical ocean. The hot sunshine makes the temperature of seawater rise, and a large amount of seawater turns into steam and rises to the sky. Sometimes the water vapor rises very fast and in large quantities, thus forming a huge suction force, which makes the surrounding cold air continuously sucked in and gradually forms a huge vortex. When the vortex turns faster and faster, it will form a typhoon. The typhoon's wind force can exceed 12, and it will be accompanied by lightning and thunder, which is very scary. Typhoon is a very terrible tropical storm, and the disaster is serious wherever it goes. On land, it will destroy roads, bridges, buildings and so on. When you are at sea, you can set off huge waves and overturn ships. Sometimes, huge waves will rush to the coast, bringing typhoons and hurricanes to people along the coast. They all belong to tropical cyclones in the northern hemisphere, just because they produce different sea areas and people in different countries call them different. In the northern hemisphere, cyclones generated on the ocean surface of Greenwich Meridian east of international date line are called hurricanes, while tropical cyclones generated on the ocean surface west of international date line are called typhoons. Generally speaking, tropical cyclones generated in the Atlantic Ocean are called hurricanes and tropical cyclones generated in the Pacific Ocean are called typhoons. The formation of a hurricane requires three conditions: warm sea water; Humid air; The wind on the ocean surface can turn the air into an inward rotating airflow. In most storm structures, the air will become warmer and warmer, and will rise higher and higher, and eventually flow to the outside atmosphere. If these upper winds are light, then this storm structure will be maintained and developed. The sky at the eye of the hurricane (that is, the center of the hurricane) is relatively calm. The most violent weather phenomenon occurs in the surrounding atmosphere near the eye of a hurricane, which is called the eye wall. At the top of the eye wall, most of the air flows out, which intensifies the upward movement of the atmosphere. Great loss. 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 a tornado? A tornado is a vortex: the air rotates rapidly around the axis of the tornado and is attracted by the extremely low air pressure in the center of the 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. The formation of tornadoes is the product of thunderstorms in 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 by 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. Detection of tornadoes What is the wind speed of tornadoes? 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 other hand, if the tornado gets closer and closer to the radar, the reflected signal will move in 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. Tornado Hazard 1995 A tornado occurred in Admore, Oklahoma, USA, and the roof and other heavy objects were blown dozens of miles away. Most of the debris fell in the tornado. ......

How did the typhoon come from, why there was a typhoon, and how did it form?

Typhoon originated in tropical ocean, where the temperature is high and a large amount of seawater is evaporated into the air, forming a low pressure center. With the change of air pressure and the movement of the earth itself, the inflow of air also rotates, forming a counterclockwise air vortex, which is a tropical cyclone. As long as the temperature does not drop, this tropical cyclone will get stronger and stronger, and finally a typhoon will form.

How do typhoons form and when do they usually occur?

Typhoon is formed because the tropical sea surface is directly exposed to the sun, which makes the sea water temperature rise, the sea water evaporates into steam, and the surrounding cold air flows in to replenish it, and then rises again. This cycle will eventually expand the whole airflow and form a "wind". Due to the vastness of the sea, the diameter of air circulation is increasing, even several kilometers. Due to the high-speed rotation of the earth from west to east, there is friction between the air column and the surface. The closer to the equator, the greater the friction, which makes the steering column rotate counterclockwise. (The southern hemisphere rotates clockwise. ) Because the earth rotates fast, the air column can't keep up with the speed of the earth's rotation, which forms the feeling of going west, which forms the typhoon and typhoon path we are talking about now. The center of the typhoon is in the position where the wind direction is T-shaped. It is not difficult to judge the distance and direction of the typhoon center according to the wind direction and wind speed. Based on my 40-year observation of the trend of clouds before typhoon Lei, it is basically accurate to judge whether the typhoon passes through the local area. The accuracy has been predicted to local areas many times. When the maximum wind speed near the ground reaches or exceeds17.2m per second, we call it a typhoon. (The following does not represent my own editing)

Judging from the typhoon structure, such a behemoth must have unique conditions.

First of all, there must be a vast atmosphere with high temperature and high humidity. The temperature and humidity of the bottom atmosphere on the tropical ocean surface are mainly determined by the sea surface temperature, and typhoons can only form on the warm ocean surface where the sea surface temperature is higher than 26℃-27℃ and the sea surface temperature is higher than 26℃-27℃ within 60 meters.

Second, there should be an initial disturbance in which the lower atmosphere converges to the center and the upper atmosphere spreads outward. Moreover, the divergence of the upper layer must exceed the convergence of the lower layer in order to maintain enough updraft and continuously strengthen the disturbance of the lower layer;

3. The difference of vertical wind speed should not be too big, and the relative motion of the upper and lower air is very small, so that the latent heat released by water vapor condensation in the initial disturbance can be stored in the air column in the typhoon eye area, forming and strengthening the typhoon warm center structure;

Fourth, there must be enough geostrophic deflection, and the earth's rotation is conducive to the formation of cyclonic vortices. The geostrophic deflection force is close to zero near the equator and increases at the north and south poles. Typhoons basically occur on the ocean surface about 5 latitudes from the equator.

Typhoons in the northern hemisphere mostly occur in July, August and September, and rarely occur from1February to April of the following year.

China coastal areas from Liaoning in the north to Guangdong and Guangxi in the south are likely to be attacked by tropical cyclones every year, with the largest number of tropical cyclones landing in Guangdong, Fujian and Taiwan Province provinces.

How is a typhoon formed?

There are at least two conditions for the formation of a typhoon: 1, relatively high temperature and sufficient water vapor. When boiling water, the water at the bottom of the pot will rise, because the water at the bottom of the pot will expand when heated. So is the air. When the air at the bottom is heated, it will rise. In areas with high temperatures, when some disturbances in the atmosphere happen, a large amount of air will rise, which will reduce the air pressure on the ground. At this time, the air outside the rising area continues to flow into the rising area. Because of the rotation of the earth, the flowing air will turn like a wheel, which is also one of the reasons for the typhoon. After the rising air expands and cools, the water vapor in it cools and condenses into water droplets, releasing heat, which in turn promotes the rise of low-level air, reduces the ground pressure and makes the air rotate more violently, thus forming a typhoon. Where do these two conditions coexist? Only on the surface of tropical oceans. The sea surface temperature there is very high, so that the lower air can fully accept the water on the sea surface. There are also the richest water tanks on the earth, which are the main driving force for the formation and development of typhoons. Without this motivation, typhoons will dissipate even if they form. Secondly, there is a certain distance from the equator, and the deflection force generated by the earth's rotation plays a certain role, which is conducive to the development of typhoon cyclone test circulation and the strengthening of airflow convergence. Third, the latitude is simple in the case of tropical ocean surface. Therefore, the air over the same sea area can often remain stable for a long time, so that typhoons have enough time to accumulate energy and brew a wind. Under this condition, typhoons will form and strengthen in some tropical marine areas as long as there is a suitable trigger mechanism, such as divergent airflow in the upper air or the encounter of trade winds in the northern and southern hemispheres slightly north of the equator. According to statistics, in tropical oceans, typhoons often occur in areas where the sea surface temperature exceeds 26 or 7 degrees. According to statistics, the ocean that produces typhoons mainly includes the ocean east of the Philippines, the South China Sea, the West Indies and the east coast of Australia. The seawater temperature in these places is relatively high, and it is also the place where the trade winds in the northern and southern hemispheres meet, so more than 20 typhoons are often born in a year.

Why is there a typhoon and how is it formed?

There are often many weak tropical eddies on the surface of tropical oceans, which we call "embryos" of typhoons, because typhoons always develop from such weak tropical eddies. Through meteorological satellites, it is found that only about 10% of a large number of tropical eddies on the ocean surface can develop into typhoons. How is a typhoon formed?

Generally speaking, the occurrence of typhoons requires the following basic conditions:

1. First of all, there must be a wide enough tropical ocean surface, which requires not only that the surface temperature of seawater is higher than 26.5℃, but also that the water temperature in a layer of seawater 60 meters deep should exceed this value. Among them, the vast ocean surface is the necessary natural environment for the formation of typhoons, because the friction between air molecules in typhoons consumes an average of 365,438+000-4,000 calories/cm **2 of energy every day, and this huge energy can only be supplied by the latent heat released by the vast tropical ocean. In addition, the strong wind around the tropical cyclone will make the sea water churn around the center, even in the typhoon center where the air pressure drops very low, and then spread around, so the sea water will churn around from the typhoon center. In a typhoon, this sea churning phenomenon can affect the depth of 60 meters. On the ocean surface where the seawater temperature is lower than 26.5℃, it is difficult to maintain a typhoon due to insufficient heat energy. In order to ensure that the sea surface temperature is always above 26.5℃ during this tumbling process, this warm water layer must have a thickness of about 60 meters.

2. There must be a weak tropical vortex before the typhoon is formed. We know that the operation of any machine consumes energy, which requires energy. Typhoon is also a "heat engine". It rotates there at such a huge scale and speed and consumes a lot of energy, so it needs an energy source. The typhoon's energy comes from the water vapor in the tropical ocean. In a pre-existing tropical vortex, the air pressure in the vortex is lower than that around it, and the air around it carries a lot of water vapor to the center of the vortex, causing upward movement in the vortex area; Wet air rises and water vapor condenses, releasing huge latent heat of condensation, which can make typhoons run. Therefore, even if there is a tropical ocean surface with high temperature and high humidity to supply water vapor, it is impossible to form a typhoon without the strong rise of air and the condensation and release of latent heat. Therefore, the upward movement of air is an important factor to produce and maintain typhoons. But the necessary condition is that a weak tropical vortex exists first.

3. There should be enough earth rotation deflection force. Because the geostrophic deflection at the equator is zero and gradually increases to the poles, the typhoon is located about 5 latitudes away from the equator. Due to the rotation of the earth, a force that changes the direction of air flow is generated, which is called "Earth rotation bias force". On the rotating earth, the rotation of the earth makes it difficult for the surrounding air to flow directly into the low pressure, but rotates counterclockwise along the center of the low pressure (in the northern hemisphere).

4. Above weak low pressure, there is little difference between high and low air direction and wind speed. In this case, the upper and lower air columns work together, and the high-altitude heat is easy to accumulate, thus heating up. Once the cyclone is generated, the ambient airflow above the friction layer will flow along the isobar, and the warming effect of the upper layer can be further completed. In the area north of 20 N, the climatic conditions have changed, mainly because the high-rise wind is very strong, which is not conducive to warming, and typhoons are not easy to appear.

These are just the necessary conditions for a typhoon. Having these conditions does not mean that there will be a typhoon. The occurrence of typhoon is a complicated process, which has not been fully understood so far.

The tropical sea surface is exposed to direct sunlight, the temperature of the sea water rises, and the evaporation of the sea water provides sufficient water vapor. However, in the process of rising, water vapor condenses, releasing a lot of latent heat, promoting the further development of convection, reducing the sea level pressure, making the surrounding warm and humid air flow in and replenish, and then rising again. This cycle forms positive feedback, that is, the second conditional instability (CISK) mechanism. On the vast sea with suitable conditions, the influence scope of the loop will continue to expand, reaching hundreds to thousands of kilometers. Due to the high-speed rotation of the earth from west to east, there is friction between the air column and the surface. The closer to the equator, the greater the friction, which causes the steering column to rotate counterclockwise (clockwise in the southern hemisphere). Because of the fast rotation of the earth, the air column can't keep up with the speed of the earth's rotation, forming a westward sense and forming what we now call typhoons and typhoon paths. The following is the description of the first volume of the geography book of senior one in People's Education Edition: In the tropical or subtropical ocean where the sea surface temperature exceeds 26℃, due to ......

How is a typhoon formed?

There are two main conditions for the formation of typhoons: first, the ocean temperature is relatively high; The second is rich water vapor. Typhoons often occur in areas where the sea surface temperature exceeds 26~27℃(60 meters deep). In the sea area with high temperature, some disturbances occurred in the atmosphere, and a large amount of air began to rise. At this time, the peripheral air in the rising sea area continuously flows into the rising area. Due to the rotation of the earth, the inflowing air rotates like a wheel. After the rising air expands and cools, it condenses into water droplets to release heat, which further promotes the rise of low-level air, makes the ground pressure drop lower, and the air rotates more violently, thus forming a typhoon.

From the above analysis, it can be seen that the conditions for typhoon formation are mostly in the tropical ocean surface or sea surface with latitude higher than 5 degrees. The sea surface temperature near Shanghai sometimes exceeds 27℃, but only the surface sea surface temperature exceeds 27℃, so it is difficult to provide enough water vapor for typhoons. There are usually few typhoons directly generated here near Shanghai, but it is a place where typhoons often pass northward.

Why do typhoons blow to land after they form at sea? In addition, how is the typhoon formed?

Not all of them will be blown to land.

Simply put, a large amount of water on the tropical ocean surface evaporates and water vapor rises, which makes the low-altitude air pressure lower. The surrounding air supplements, and the water on the ocean surface continues to evaporate and rise, forming a continuous updraft. Coupled with the earth's rotation, there is a great eccentric gravity, which causes the airflow to become a large rotating cyclone cloud. Generally, it is a tropical storm when it is first formed, and it becomes a typhoon due to the decrease of intensity during the implementation. Generally speaking, there is a lot of rainfall and strong wind, and the cyclone center of the typhoon has the greatest wind.