What caused the rainstorm?

Question 1: How did the rainstorm form? Rain with heavy rainfall intensity. The rainfall per unit time is called rainfall intensity. China's meteorological department stipulates that the 24-hour rainfall is greater than or equal to 50 mm, which is a rainstorm; Heavy rain occurs when it is greater than or equal to 100 mm; It's a rainstorm of 200 mm or more. The world's largest rainstorm occurred in Reunion Island in the South Indian Ocean, with a 24-hour rainfall of 1.870 mm, and the largest rainstorm in China occurred in Xinliao, Taiwan Province Province, with a 24-hour rainfall of 1.672 mm. Extreme rainstorm is a disastrous weather, which often causes floods and serious soil erosion, leading to major economic losses such as engineering accidents, dike breaches and crop flooding. However, moderate heavy rain is an important source of water resources, which can be used to promote profits.

Abundant and persistent water vapor, strong and persistent upward movement of airflow and instability of atmospheric stratification are the main physical conditions for heavy rain. The favorable combination of various scales of weather system and underlying surface, especially topography, can produce heavy rain. The main weather systems that cause large-scale rainstorm in China are fronts, cyclones, shear lines, eddies, troughs, typhoons, easterly waves and intertropical convergence zone. In addition, thermal thunderstorms will also cause short-term and small-scale heavy rains in arid and semi-arid areas.

China is a rainy country. Except for some provinces and regions in the northwest, it is almost always heavy rain. Winter rainstorm is limited to the coastal areas of South China, with frequent rainstorm in South China from April to June. From June to July, persistent rainstorms often occur in the middle and lower reaches of the Yangtze River, with long duration, wide range and large amount of rainstorms. July-August is the main rainstorm season in northern provinces, and the rainstorm intensity is very strong. From August to 65438+ 10, the rain belt gradually withdrew southward. After summer and autumn, the typhoon rainstorm in the East China Sea and the South China Sea is very active, and the point rainfall of typhoon rainstorm is often very large.

In people's impressions and various literary works, rainstorm is instantaneous heavy rain, such as downpour and downpour, but in meteorology, rainstorm is the weather condition of a day. If the rainfall in a place is greater than or equal to 50mm within 24 hours, the weather in this place is rainstorm, and the rainstorm in people's mind is called short-term heavy rainfall.

Storm (full text)

I feel very honored to have the opportunity to introduce the rainstorm to you today. Today, I will systematically introduce the formation of rainstorm, the disasters caused by rainstorm, and how to monitor and forecast rainstorm, mainly introducing these contents. Rainstorm is a very important disaster in China, especially in the Yangtze River basin. Or the whole area south of Huaihe River in China. Of course, there was a big flood in the Yellow River. So in general, rainstorm is a major meteorological disaster in our country, so everyone is concerned that there was another flood in the Huaihe River Basin during the flood season in 2003, so this picture is a satellite cloud image released by Fengyun-2 meteorological satellite developed by our country, and we can see a cloud belt over the Huaihe River Basin for a long time.

So, for example, 1998, due to the flood in the Yangtze River basin, the whole country lost more than 300 billion RMB. /kloc-more than 0/000 people were killed in the flood. Therefore, flood disaster is different from drought. Flood disaster is like an acute disease, which will cause sudden losses to people's lives and property. Generally speaking, drought, like our chronic disease, affects for a long time. It will also cause great losses, but it is mainly the economy, especially agricultural production. So from this table, we can see that in recent years, our country as a whole has suffered more and more losses due to meteorological disasters. With the development of China's national economy, the losses caused by meteorological disasters also increase with the development of national economy. So this is obvious from above.

We are also a flood disaster. For example, on August 5, 2006, there was a tropical cyclone in Shanghai from 1 to 10, which caused a heavy rain and flooded the whole Shanghai. So a disaster like this, if everyone knew it twenty years ago, was that several quilts were wet. But today, every family has all kinds of household appliances, and soaking in water will cause great losses. The same is true in that factory. The equipment in the factory now can't be compared with the factory decades ago. Therefore, with the development of China's national economy, the losses caused by rainstorm disasters to China's entire economy are becoming more and more serious. So this picture is caused by the flood in the Huaihe River basin, and we can see the flood in the countryside.

So it is very important to forecast the rainstorm now, because the flood >>

Question 2: How is the rainstorm formed? The formation process of rainstorm is quite complicated. Generally speaking, from the macroscopic physical conditions, it is an abundant and continuous water vapor flow, a strong and lasting upward movement of air flow, and an unstable atmospheric structure. The favorable combination of weather system and underlying surface, especially topography, can produce heavy rain. Rainstorms often fall from cumulonimbus clouds. The updraft in the cumulonimbus cloud is very strong, the vertical speed can reach 20 ~ 30m/s, and the maximum speed can reach 60m/s, even higher than the wind speed of typhoon. In the strong updraft, water droplets are increasing. The conditions for the formation of cumulonimbus clouds are that the atmosphere should contain enough water vapor and have strong upward movement, so that the water vapor can be transported upward quickly and the water droplets in the clouds will fall sharply to the ground until the upward airflow can not support it. The weather systems that cause large-scale rainstorm in China mainly include fronts, air, shear lines, eddies, troughs, typhoons, easterly waves and intertropical convergence zone. In addition, thermal thunderstorms will also cause short-term and small-scale heavy rains in arid and semi-arid areas.

According to China's meteorological regulations, within 24 hours, the rainfall falling from the air is 50.0 mm and 99.9 mm, 100.0 mm to 199.9 mm, and the rainfall exceeding 200.0 mm is a torrential rain.

Question 3: The reason for the rainstorm in South China is that the abnormal atmospheric circulation is the "culprit"

"The direct cause of the recent rain and snow weather is abnormal atmospheric circulation," said Sun Jun, chief forecaster of the Central Meteorological Observatory.

This year's atmospheric circulation anomaly is related to the "La Nina event" that is taking place in the equatorial Middle East Pacific. Li Weijing, deputy director of the National Climate Center, said that from the perspective of climate change, the current low temperature in the equatorial Middle East Pacific is one of the manifestations of the "La Nina" phenomenon. Statistical analysis shows that the meridional dimension of mid-latitude atmospheric circulation may be strengthened in the winter of the year and the spring of the following year when the strong La Nina event occurred, that is, frequent cold air activities may easily lead to low temperature in most parts of northern and eastern China and more precipitation in the north of the Yangtze River.

Why is this year's heavy snow so slow to "recede"? Experts attribute the reason to the stability of atmospheric circulation. Sun Jun said: "It is precisely because of the stable atmospheric circulation during this period that the warm and humid airflow and cold air in the southwest have been around 30 degrees north latitude, especially in the middle and lower reaches of the Yangtze River, so there will be no obvious turning point in the recent rain and snow weather."

Question 4: How is the stormy weather formed? Abundant and persistent water vapor, strong and persistent upward movement of airflow and instability of atmospheric structure are the main physical conditions for heavy rain. The favorable combination of various scales of weather system and underlying surface, especially topography, can produce heavy rain. The main weather systems that cause large-scale rainstorm in China are fronts, cyclones, shear lines, eddies, troughs, typhoons, easterly waves and intertropical convergence zone. In addition, thermal thunderstorms will also cause short-term and small-scale heavy rains in arid and semi-arid areas.

In China, the water vapor of rainstorm comes from the South China Sea or the Bay of Bengal. Second, from the East China Sea or the Yellow Sea. Sometimes, in a rainstorm, water vapor comes from the east and south, or mainly from the south in the early stage and from the east in the later stage. "Southeast wind, the ancestor of rain" spreads in the Central Plains of China, which is an objective reflection of precipitation law.

Like running water, the motion of the atmosphere often produces fluctuations or eddies. When two air streams from different directions or different temperatures and humidity meet, fluctuations or vortices will occur. The largest is several meters in Qian Qian, and the smallest is only a few kilometers. In these fluctuating areas, with the operation of air flow, upward movement often occurs, and horizontal water vapor quickly concentrates in the same area, forming a rainstorm center.

In addition, topography also has an influence on the formation of heavy rain and rainfall. For example, due to the existence of mountains, the airflow is forced to rise on the windward slope, which increases the vertical movement and the rainstorm; On the leeward slope of the mountain range, the airflow sinks and the rainfall is greatly reduced. On some leeward slopes, the rainfall is only110 of windward slopes.

Question 5: Reasons for the formation of rainstorm in China Many rainstorm weather processes in China occur under the interaction of mid-high latitude and low latitude systems, which can be summarized into the following six situations: 1, (intertropical convergence zone) northward 2, strong easterly jet formed by offshore typhoon and north subtropical high 3, combination of landing typhoon and mid-latitude westerly trough 4, superposition of easterly wave (or typhoon inverted trough) 5, south branch trough and Meng.

Question 6: Causes of rainstorm and flood disasters The rapid increase of river water volume caused by rainstorm is accompanied by a sharp rise in water level.

The characteristics of rainstorm and flood are mainly determined by rainstorm and restricted by the underlying surface conditions of the basin.