Sandstorms are caused by strong winds blowing over loose soil or sand, and picking up so much of that material that visibility is reduced. In desert regions at certain times of the year, sandstorms become more frequent because the strong heating of the air over the desert causes the lower atmosphere to become unstable. This instability mixes higher winds in the middle troposphere downward, producing stronger winds at the surface. In the United States, these events are often referred to as "dust storms".
很简单很短了啊..
