This aerial photo shows the leading edge of a haboob—an...

This aerial photo shows the leading edge of a haboob—an intense dust storm—sweeping across Texas last week. Although dust can be stirred up under many circumstances, haboobs are a specific meteorological phenomenon with winds as high as 100 kph and towering clouds of dust kilometers high. This particular storm swept through five US states last week along an incoming cold front. The winds accompanying the cold front swept up silt, dirt, and dust from the drought-ridden Southwest and carried it along to envelope towns and cities along the way. Although the term is Arabic in origin, haboobs occur throughout the world, typically at the leading edge of a cold front or thunderstorm.  (Photo credit: R. Scott)