Causes of tropical storm tide formation

Question 1: What is a tropical storm (typhoon) and how is it formed? The main energy of typhoon is the latent heat released by the condensation of hot and humid air. According to statistics, typhoons can only form when the sea water temperature reaches above 27.5℃. From July to September, the highest sea surface temperature in the southwest of the North Pacific Ocean is 28℃, and the isotherm reaches about 30 N to the west of165 E, so typhoons usually occur in early autumn.

The second condition of typhoon is the function of atmospheric circulation. One of the conditions of atmospheric circulation is the convergence of airflow in the lower circulation, because airflow convergence is the necessary mechanism for a large amount of air to rise and release latent heat. In low latitudes, convergence can be mainly formed by equatorial convergence zone and easterly wave.

The equatorial convergence zone is the intersection of the northeast trade winds in the northern hemisphere and the southeast trade winds in the southern hemisphere. In summer, the equatorial convergence zone moves to the northern hemisphere, and the southeast trade winds in the southern hemisphere cross the equator to become the southwest airflow in the northern hemisphere under the action of bias, so the equatorial convergence zone appears as a convergence zone between the northeast airflow and the southwest airflow in summer. The air pressure in this confluence zone is low, which can also be called equatorial trough. Convection development in equatorial trough, thunderstorm weather. The easterly wave is a wave in the northeast trade wind area on the south side of the subtropical high. It is an inverted trough in the pressure field from northeast to southwest, with the northeast wind in the front (west) and the southeast wind in the back (east). The easterly wave is deep, especially in the upper troposphere above 500 hPa, and its moving speed is about 2 1 km/hour. According to statistics, about 25% of the easterly wave may develop into a typhoon.

Because the convergence zone and easterly wind mostly appear in the easterly belt of subtropical high or its southern edge, the north-south position of subtropical high has a great influence on typhoon formation. The main subtropical high in the northern hemisphere is the North Pacific subtropical high and the North Atlantic subtropical high, which is located in the South Asia high in the southern part of the Asian continent. It is the North Pacific subtropical high that affects the formation of typhoon, and the southwest edge of the North Atlantic subtropical high is the active area of another tropical cyclone-hurricane.

Question 2: The causes of tropical storms in Fiji. Fiji has a tropical maritime climate. From May to 65438+February every year, Fiji is affected by the cold southeast wind, and the temperature is low, with an average temperature of 22 degrees Celsius, which is also the driest period of the year. 65438+February-April, the temperature is high, the average temperature is 32 degrees Celsius, the wind direction is changeable, and there is more rainfall. Fiji's natural conditions are suitable for the growth of birds, but there are few wild animals. The southeast or windward side of most islands has humid climate, lush plants and relatively dry and barren leeward side. Fiji has a unique tropical monsoon climate, which is suitable for tourism all year round.

Question 3: The hazards of tropical storms. Tropical storms are very harmful! ~ tropical storms often occur in coastal areas. Tropical storms cause strong winds, heavy rains and huge waves, which have great destructive power to coastal urban facilities, ships at sea and agricultural production in coastal areas. How to reduce the harm of tropical storms to people themselves?

1. Pay attention to the weather forecast and make preparations for prevention.

2. The parts of the house that need to be reinforced should be reinforced in time, and the doors and windows should be closed.

3. Prepare food, drinking water, lighting, rain gear and necessary medicines to prevent accidents.

4. Dredge the drainage facilities and keep them unobstructed.

When the tropical storm comes, try to stay indoors and reduce going out.

6. In case of strong wind and lightning, pay attention to the use of electrical appliances to prevent electric shock.

7. Pay close attention to the surrounding environment, and transfer in time in case of floods, landslides and other situations that endanger the safety of houses.

8. After the storm, we should pay attention to health and epidemic prevention to reduce the spread of diseases.

Question 4: 1969 causes of storm surge in the United States 1934 In the early morning of May, a black storm unprecedented in human history occurred in the grassland area of the western United States. The storm blew for three days and nights, forming a huge black storm belt with a length of 2400 kilometers from east to west, a width of 1440 kilometers from north to south and a height of 3400 meters. Where the storm passed, streams were cut off, wells dried up, fields cracked, crops withered, livestock died of thirst, and thousands of people were displaced.

This is nature's historic punishment for human civilization. As developers continue to reclaim land resources and cut down forests, soil wind erosion is serious, and continuous drought has aggravated the phenomenon of land desertification. Under the action of high-altitude airflow, dust rolled up and thick dust rose into the sky, forming a huge gray-black storm belt. * * * published a special report on the front page of that day.

The attack of the black storm had a serious impact on the agricultural and livestock production in the United States, which caused the drought-stricken wheat to wither and die in a large area, which caused the fluctuation of the American grain market at that time and impacted the economic development. At the same time, the black storm plundered all the way, scraped off the fertile soil surface, exposed the barren sandy soil layer, changed the soil structure in the disaster-stricken areas, and seriously restricted the future development of agricultural production in the disaster-stricken areas.

After the Black Storm in North America, the former Soviet Union did not learn from the lessons of the United States, and history repeated itself twice. 1960 In March and April, the newly reclaimed areas in the former Soviet Union were once again eroded by the black storm, and all the farms that had been operating for many years were destroyed within a few days, and no grain was harvested. Nature's revenge on mankind is merciless. Three years later, another storm occurred in these newly reclaimed areas, and the impact of this storm was more extensive. The newly reclaimed land in Kazakhstan has affected 20 million hectares of land.

1) Main characteristics of storm surge

Storm surge refers to the abnormal rise of sea level caused by strong atmospheric disturbances such as tropical cyclones (typhoons, hurricanes) and temperate cyclones. The sea level fluctuation recorded by coastal tide gauge stations or estuary water level stations is usually a comprehensive feature of sea level change caused by long-wave vibration such as astronomical tide, storm surge and tsunami. The general tide gauge has filtered out the sea surface fluctuation caused by short-period waves for a few seconds. If the storm surge happens to coincide with astronomical events (especially astronomical events during the astronomical tide), the storm surge is often accompanied by violent wind and waves, which go upstream with the river flood, and often make the tidal waves in the affected coastal areas soar, even the tidal waves destroy the seawalls and engulf the docks, factories, towns and villages, making it impossible for materials to be transferred and people and animals to escape, thus causing great disasters.

Some people call storm surge "storm tsunami" or "meteorological tsunami". In China historical documents, it is often called "sea overflow", "transgression", "tsunami" and "tidal wave", and storm surge disaster is called "tidal disaster". The spatial range of storm surge is generally from tens of kilometers to thousands of kilometers, and the time scale or period is about 1- 100 hours, which is between earthquake tsunami and low-frequency astronomical tide wave. However, sometimes the affected area of storm surge will move with the movement of atmospheric disturbance factors, so sometimes a storm surge process can affect one or two thousand kilometers of coastal areas for several days.

Scholars at home and abroad mostly divide storm surges into typhoon storm surges caused by tropical cyclones (or tropical storm surges, which are called hurricane storm surges in North America and tropical cyclone storm surges along the Indian Ocean coast) and temperate storm surges caused by temperate weather systems such as temperate cyclones. China is one of the few countries in the world where two kinds of storm surge disasters are very serious. Storm surge disasters can occur all year round, and the coastal areas from south to north are not spared. Storm surge is usually named after the weather system that causes storm surge at home and abroad. For example, the storm surge caused by typhoon 1980 (internationally known as typhoon Joe) is called typhoon 8007 or storm Joe; 1969 The storm surge caused by Hurricane Camille, which landed in North America, is called "Camille storm surge".

Whether the storm surge can cause disasters depends largely on whether the maximum storm tide level overlaps with astronomical tide, especially with the astronomical tide cycle. Of course, it also depends on the geographical location, coastal morphology, coastal and seabed topography of the affected areas, especially the socio-economic (disaster-bearing body) situation in the coastal areas. If the maximum storm tide level coincides with astronomical tide, it will lead to catastrophic tidal disasters, such as typhoon storm surge of 8923 and 92 16. 1 28 August 1992 to128 September 1992, the eastern coast of China was affected by the strong tropical storm 16 and astronomical tide. & gt

Question 5: What are the causes of hurricanes? Air vortex formed by convection of cold air and hot air under the action of geostrophic deflection force.

Question 6: The cause of typhoon formation: Typhoon.

Typhoon is a powerful and deep tropical cyclone formed in the tropical ocean. Typhoon classification The National Meteorological Administration of China stipulates that the international tropical cyclone name and grade standard shall be used from 1989 1 month. According to international standards, the maximum average wind force near the center of tropical cyclone is less than 8, which is called tropical depression, 8 ~ 9 is called tropical storm,10 ~1is called strong tropical storm, and1is called typhoon. In order to issue typhoon warnings uniformly, the typhoons that appear in the west of150 E and on the northern surface of the equator every year are numbered in the order of appearance. For example, Typhoon 9202 means that this typhoon is the second typhoon west of 1992. Typhoon activity is seasonal. The typhoons that affect China mainly occur from May to 10, especially from July to September. The source of the typhoon is the 22222222 area. Typhoon sources are distributed on the ocean surface with islands near 5 north latitude and 20 south latitude. Typhoons affecting China are mainly formed in the western Pacific Ocean to the east of the Philippines, near Guam and in the middle of the South China Sea.

Typhoon structure and weather A mature typhoon is divided into three parts according to its structure and weather: typhoon eye, vortex storm area and peripheral gale area, which are arranged concentrically from the center to the outside. The typhoon eye is located in the center of the typhoon, with a diameter of about 5 ~ 10 km. Downward flow prevails at the eye of the typhoon, so the weather is clear and windless. Outside the eye of the typhoon is a vortex wind and rain area, where strong convergent updraft prevails, forming thick clouds, and violent storms occur from time to time. The wind force is often above 12, which is the worst weather area for typhoons. Further outward is the peripheral windy area, and the wind speed decreases outward, and the wind force is generally above 6. Typhoon crossing often brings stormy weather, causing huge waves on the sea surface and seriously threatening navigation safety. After landing, it can destroy crops and various building facilities. It has caused great losses to people's lives and property and is a disastrous weather with great harm.

The formation of typhoon must meet the following conditions: ① A vast ocean with high temperature. The formation and development of typhoons need huge energy, which mainly comes from the latent heat released by a large amount of water vapor condensation. On the surface of tropical ocean, seawater has high temperature and strong evaporation, and a large amount of heat and water vapor are transported into the atmosphere through turbulent motion, which has unstable conditions of high temperature and high humidity, and a large amount of internal energy is a huge energy source for typhoon generation and development. ② Suitable flow field. Appropriate circulation conditions can start and induce high temperature and high humidity air to generate disturbance, so that the airflow convergence will rise. ③ Proper geostrophic deflection. After the airflow moves, there must be a certain steering force. If the geostrophic deflection force does not reach a certain value, the airflow gathered at the center will reach the low-pressure center, so that cyclone vortex cannot be formed and typhoon cannot be formed. So typhoons usually occur between 5 degrees and 20 degrees north latitude. ④ The vertical shear of wind should be small. Under the action of geostrophic bias, the convergent updraft develops into a cyclonic vortex. The air flow rises, adiabatic cooling produces condensation, and the latent heat released by condensation heats the air. The vertical shear of the wind becomes smaller, so that the latent heat does not spread outward, maintaining the warm core structure of the typhoon. The feedback from the warm heart makes the air pressure in the center of the typhoon drop continuously, and the air vortex becomes stronger and stronger, which eventually develops into a typhoon.

The movement of the typhoon will move after the typhoon is formed. The moving path basically moves from east to west along the outer edge of subtropical high. However, influenced by many factors, the moving path is very complicated. Take the typhoon movement path in the western part of the North Pacific as an example, its path is divided into three: ① westward movement path. The typhoon moved westward from the eastern Philippines, crossed the South China Sea and landed in Hainan Island or Vietnam. ② Northwest path. The typhoon moved from the east of the Philippines to the northwest, crossed the Ryukyu Islands and landed in Jiangsu, Zhejiang and Fujian provinces. ③ Turning path. The typhoon moved from the east of the Philippines to the northwest, then turned to the northeast, and its path was parabolic.

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