文档介绍：sandstrom
What is "sandstorm"?
Sandstorm is a meteorological monly found in arid and semi-arid regions. It is resulted from convection currents created by intensive heating of the ground. These currents can create wind up to 120km/h and appear as a solid wall of dust as much as 1,525m high which blow over a long distance.
Sandstorm is a kind of climatic hazard. It occurs when strong wind raises and carries along clouds of sand or dust which is so dense that it obscure the sun and reduce visibility to less than 1 km. Sandstorm usually occurs in deserts or areas near to arid and semi-arid regions. It was found in areas like Sahara Desert in North Africa, Central Australia, Southwest of USA, Central Asia and Northwest China.
Conditions for the formation of sandstorms
A specialist in meteorology pointed out that sandstorms were formed under three conditions: strong wind, rich source of sand and unstable air conditions. The three conditions can be a result of natural causes. However, for the second condition, the supply of sand is more of a result of desertification caused by human activities.
Duststorms are largely created by man himself. On the one hand, too much air pollution causes a greenhouse effect, which, in turn, leads to global wanning in climate. This results in wet places on the earth even wetter and dry places even drier. On the other hand, over grazing, poor fanning, tree cutting, strip mining all leave theland unprotected. When the wind blows, it blows away topsoil and loose soil.
The hazards, and its harm sandstorm way generally can be classified into four types: sand buried, wind, wind and atmospheric pollution environment.
Harm
The things we need to do
return farmland to forest and grassland, restore natural ecological protecting belt
restore the already-damaged grassland as soon as possible