Sandstorm in China Issue on Weather & Climate

A news extract  (18/3/2002) Sandy winds swept Beijing this weekend for the first time this year, forcing residents who hoped to enjoy warm spring weather to cut their plans short. Winds with forces of 5 to 6 on the Beaufort scale were wrapped in dust and dominated the sky in China's capital from late Friday until Sunday. Meteorologists said it would end today.

Questions to think about:  Identify the climatic hazard. (1)  Explain how the climatic elements favour the occurrence of this kind of hazard in winter. (6)  Account for the formation of the hazard. (5)  Describe the effects brought by the hazard. (4)  Suggest some measures to minimize the negative impacts brought by the hazard. (3)

Areas affected by sandstorms Mongolia Gansu Xinjiang

What is the hazard?  It is sandstorm/dust storm.  Tonnes of sands are blown away by strong winds.

Favourable climatic elements for the occurrence of sandstorms  Strong winds are brought by the intense high pressure/anticyclone  which is centred at the continental interior of China/Mongolia  because it is winter in the northern hemisphere  Temperature is lower over land than the sea  Air sinks and high pressure is formed  Winds are out-blowing and strong,  in clockwise directions  Winds are NW, offshore and dry

Another news extract  Reports from the Beijing Meteorological Station said the recent sandstorms were brought by a cold front from Mongolia. It blew fine sand from the Inner Mongolia Autonomous Region and Shanxi and Hebei provinces all the way to Beijing.

A satellite picture Direction of sandstorm

Formation of sandstorm  Spreading of desert  Low annual rainfall  High temperature in summer  Deforestation  Poor farming methods  Over-cultivation  Over-grazing in some provinces e.g. Mongolia  Lead to the loss of protective layer   Soil erosion  Loosen soil blown away by strong winds  Causing sandstorms

Effects of sandstorm  Lower visibility in urban area  A lot of dust in the air  dusty weather  Air pollution  Damage crops  Economic loss  Loss of property  Disrupt transport e.g. air/road transport

Solutions  Prevention: to set up warning system to minimize loss  Precaution: afforestation/plant more trees  To prevent soil erosion  Limit grazing over land/limit the no. of herds (animals kept by the farmers)  Introduce scientific farming methods  To prevent the deserts from spreading