Severe weather is the weather that seriously threatens people's lives and property, and causes heavy losses to industry, agriculture and transportation.asgale, rainstormhail、tornado、cold wave, frost, fog, etc.It can occur in different seasons and is usually sudden.
China has a vast territory and complex natural conditions, which are typicalMonsoon climate zoneTherefore, there are many kinds of disastrous weather, and there are great differences between different regions.
Disastrous weather is caused bymeteorological disaster The direct cause of.Studying the formation mechanism and change law of disastrous weather and monitoring the formation and development process of disastrous weather are the basis for forecasting meteorological disasters and disaster prevention and reduction.
When strong cold air invades southward, it often causes severe cooling, accompanied byfreeze injury, strong wind, etc.This kind of weather process is called cold wave.According to the regulations of the China Meteorological Administration, due to the invasion of cold air, the temperature drops by more than 10 ℃ within 24L, and the lowest temperature drops below 5 ℃, which is called cold wave.If the temperature within 24L drops by more than 14 ℃, there are 3~4 large administrative regions on land with gales above level 7, and all coastal areas with gales above level 7, it is called strong cold wave.According to the needs of industrial and agricultural production and national defense construction, various supplementary provisions have been made for the standards of cold wave.
Frost refers to a short period of low temperature weather in warm season (average temperature higher than 0 ℃) when the temperature of soil surface, plant surface or air layer close to the ground drops enough to cause damage or death of plants.
Chilling injury
Chilling damage is different from freezing damage, which refers to the damage caused by freezing water in plants when the temperature drops to 0 ℃ or below.The chilling injury refers to the low temperature weather in which the temperature drops below the lower limit temperature (but still above 0 ℃) of the growth stage of the crop at that time during the growth period of the crop, which hinders the physiological activities of the crop and even destroys the crop tissue.
Dry hot air
Dry hot wind weather is a kind of atmospheric drought phenomenon with high temperature, low humidity and certain wind force.Dry hot wind is one of the main meteorological disasters that affect wheat, cotton and other crops in northern China.Different regions have different names according to the characteristics of dry and hot wind, such as "fire wind", "hot wind", "dry wind", etc.
Drought and flood
The dry weather is mainly formed under the long-term control of high pressure.In spring, the mobile cold high often moves from west or northwest to east through North China.In North China and Northeast China, it is sunny with few clouds, the temperature rises quickly, the air is dry, and the wind is windy, the evaporation intensity is high, which often leads to spring drought.In July and August in summer, the subtropical Pacific high moves northward, and the Yangtze River basin is under its control. In July and August, there is usually no rain for twenty or thirty days. The weather is sunny, evaporation is strong, and summer drought occurs.In autumn, the subtropical high retreated to the south, and the Siberian high pressure strengthened and extended southward. The high and cool weather in autumn appeared in central China, causing drought in autumn.In essence, drought is the result of the comprehensive influence of atmospheric circulation, topography, soil conditions, human activities and other factors.It occurs in all major agricultural regions in China and is one of the important disastrous weather in China.
Flood weather is caused by rainstorm or continuous rain.The main weather systems are cold front, stationary front, frontal cyclone and typhoon.The cold front activity can produce strong frontal rain in a large range;Frontal cyclones will cause precipitation for a long time;Typhoon rainstorm mainly occurs in summer and autumn, and in combination with other weather systems, it will produce extremely heavy rainfall.
Gale and typhoon
The disasters caused by strong winds are multifaceted and have an impact on industry, forestry, animal husbandry and fishery, especially on agricultural production.The strong wind in spring can accelerate the evaporation of soil moisture and aggravate the threat of drought;In dry and loose soil, when encountering strong wind, the topsoil is easy to be blown away, forming wind erosion. The higher the wind speed is, the more seriously the cultivated soil is eroded, so that the seeds sown are exposed, or the topsoil is blown away together.When the wind speed weakens, the larger sand grains in the blown dust will settle and accumulate, burying farmland seedlings. In the long run, farmland will become barren.This kind of sandy wasteland is distributed and spread in the coastal areas of northwest China and south China.The strong wind in summer often makes crops lodging or stalk folding.The strong wind in autumn can shake down the fruits of crops and fruit trees.The strong wind in winter, "white hair wind" (the strong wind above level 7 in the pastoral area with snow), often blows away the livestock, causing them to freeze or starve to death when they get lost.
Typhoon is a cyclonic vortex formed on the tropical ocean, which is the main disastrous weather in the coastal areas of China.When a strong typhoon strikes, it often brings stormy weather, which is easy to cause loss of people's property and has a great impact on agricultural production.But it also has its advantages.The dog days in southern China and middle China, such asSubtropical highUnder control, drought and little rain, while typhoon brings abundant rainfall, which can not only relieve drought, but also play a role in heatstroke prevention.The typhoon rain is an important source of autumn precipitation in the above areas, especially in the years of drought in autumn.
hail
Hail is a severe disastrous weather because of its high frequency, wide geographical distribution and strong destructiveness.Hail weather is generally fierce with high intensity, accompanied by strong winds and torrential rains, which is extremely harmful to crops, ranging from reduced production to no harvest in heavy cases, and can also damage buildings, endangering the safety of people and animals.[1]
Early warning signal
Announce
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According to the type and intensity of disastrous weather and the time and degree of forecast assurance that affect the region, it can be roughly divided into two types: public release and internal release, and the release names can be divided into:
1. News: When the disastrous weather is far away from or has not yet affected the area or is expected to be of ordinary harm, "news" can be issued as needed to report the disastrous weather conditions. When the alarm is lifted, it can also be reported or issued in the form of "news".
2. Alarm: It is expected that the disastrous weather will attack or affect the region or sea surface in the next 1-2 days, and the "alarm" will be issued when the impact is relatively large.
3. Emergency warning: It is expected that in the next 24 hours, when the disastrous weather will attack the region or the sea, and the danger is great, the "emergency warning" will be issued.
The symbols of disaster weather warning signals are:
The early warning signal level is generally divided into four levels. According to the severity and urgency of the disaster, the four colors of blue, yellow, orange and red are used in turn. At the same time, the signs in Chinese and English represent general, serious, serious and especially serious respectively.
preventive measure
Announce
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1. Release the potential forecast of sudden weather;
2. Use modern observation means such as automatic weather stations, radars, satellites, etc. to train meteorological informants and establish a dense observation network system at the space-time scale;
3. Meteorological departments at all levels shall establish relevant emergency plans, and use advanced telecommunication means (such as mobile phones) and media (such as radio and television) to timely release meteorological information when sudden weather comes;
4. In addition, actively publicize relevant knowledge on the prevention of sudden meteorological disasters in peacetime.[2]
