Disastrous Weather

Meteorologically specified severe weathers include typhoon, rainstorm, strong wind, hail, fog, dust storms, tornadoes, lightning, snow, freezing rain and ice, frost, low temperature, cold wave, high temperature, dry hot wind, haze and so on.

According to the definition of natural disasters, disastrous weather is obviously a natural event, because it meets the requirements of natural attribute of natural disasters, and except rainstorm, most of disastrous weathers can directly cause life casualties and human social property loss. The strong winds generated by tropical cyclones, extratropical cyclones, cold fronts, and tornadoes can directly damage some buildings and ships, and the stronger the winds, the greater the damage; Hail can hurt people and animals, and damage vehicles, buildings, etc; Fog and dust storms pose a great threat to traffic safety, and dust storms also have an adverse effect on human, animals and precision instruments; Lightning strikes have become the leading cause of death, and have destructive effects on electronic equipment and transmission lines; Heavy snow and road freezing cause traffic jams; The freezing rain can cause overhead transmission lines to be frozen, which can result in disconnection and collapse of transmission lines when the thickness of icing exceeds the bearing capacity; Low temperature, high temperature and frost have adverse effects on human health and agricultural production, and especially dry hot wind reduces wheat production; Avalanches often cause injuries to mountaineers and skiers; Haze is also harmful to human health. All of these have direct effects on human life. So these disastrous weathers, to some extent in meteorology, should be meteorological disasters at the same time. However, rainstorm is not a meteorological disaster, because although it is a severe disastrous weather, it does not necessarily directly cause casualties and loss of human social property and it mainly causes secondary disasters, such as flood, geological disaster and so on. Besides, heavy rain does not necessarily result in direct casualties or economic losses, for example, when the cumulative rainfall reaches 50 mm within 24 hours, it will not cause disasters in most parts of South China, but in the north especially with poor geological environment and ecological environment, even rainfall less than 50mm may also cause geological disasters or flash floods. Besides, in the south, when the water level of river basins is very high, for example, reaching the guaranteed water level, even the daily rainfall of river basins, less than 50mm, may also leads to high risk of flooding, and moreover, the amounts of rainfall which cause high risk in different river basins or even in different sections of the same river basin are different. So, in this sense, strictly speaking, rainstorm is not a meteorological disaster.