Geography of senior high school: Why are the conditions of sandstorm mainly drought, strong wind and strong upwelling? Especially "relatively strong upwelling" is an important one.

In the geographical area corresponding to drought, if the south is "wet", there will be no sandstorm even if there is updraft and strong wind; Upflow can be understood as the central low pressure, the surrounding high pressure, and the high pressure blows to the low pressure, forming a strong wind; The central air pressure is forced to rise, forming an updraft. Therefore, the reasons for the formation of sandstorms are the above three (if there is a low pressure at sea, then the weather formed is a "typhoon").