Dust storm refers to large amounts of sand lifted into the air by strong winds and is a type of weather that deteriorates visibility. It is basically a byproduct of drought and desertification. Meteorological scholars define weather which reduces visibility to less than 1 kilometer as "dust storm," with stronger dust storm called "black wind" sometimes reducing visibility to less than 50 meters. Each year during spring and winter, dust storm often occur in the northern regions of China and the sands from these storms travel east to affect Japan, Korea, and other regions. Only under certain unique conditions do these sand storms affect Taiwan. However, as the desertification of China's inner Mongolia region becomes more severe, plus the droughts induced by the global climate shift, uneven rainfall and other elements, the frequency and strength of dust storm is showing a trend of increasing, which in turn has further impacted Taiwan.