Causes of sandstorms
In desert areas, sandstorms are most commonly caused by either thunderstorm outflows, or by strong pressure gradients(气压梯度)which cause an increase in wind speed over a wide area. In some cases, dust and sand may set a limit to a shallow depth by a low-lying temperature change.
Sand storms have also been shown to increase the spread of disease across the globe. Virus in the dust is blown into the atmosphere by the storms. Some diseases may not be urgent at the very beginning, but they can develop into deadly ones if left untreated.
Sandstorms cause soil loss from the dry lands, doing harm to agriculture. Sandstorms also reduce visibility, affecting airplanes and road transportation.
Dust can also have good effects. Central and South American rainforests get most of their mineral nutrients from the Sahara; iron-poor ocean regions get iron.
A.Effects of sandstorms. |
B.Bad results caused by sandstorms. |
C.People know little about the effects about sandstorms. |
D.In other cases, dust may be blown as high as 6,100 meters high. |
E.Dryland farming is one of the most serious practices. |
F.For example, a breathing problem can lead to lung cancer, while dry eyes lead to blindness. |
G.In addition, sandstorms also discourage visitors from visiting these places, striking tourism. |