HKDSE Geography/E2/Causes of Sandstorms
A sandstorm occurs when winds blow over an arid or semi-arid area, carrying clouds of sand and dust which are carried by suspension or saltation.
- The desert is barren with no vegetation cover, and dry with no rainfall. There is no vegetation cover to block winds.
- Rising temperature in spring causes frozen soil and the snow cover to thaw.
- There is still a high-pressure centre over Mongolia and Siberia which brings gusty northwesterly winds to China.
The Takla Makan Desert in Xinjiang and the Gobi Desert in Nei Mongol provide a lot of sand. Under unstable atmospheric conditions and an increase in temperature (leading to uprising currents), strong northwestly winds blow across such regions and bring sand along, and sandstorms occur.
Rapid population growth leads to overgrazing, overcultivation and overcutting. They leave the land barren and unproductive and you know the drill.