STS068-244-93 Collapsed Thunderstorm, Pacific Ocean October 1994 The large circular area of a recently collapsed thunderstorm is seen in this photograph. It is located just north of the equator near the island and atolls of the Federated States of Micronesia in the Pacific Ocean. Thunderstorms form when the atmosphere is unstable and moist warm air near the surface rises. If the differential air temperature is great enough, thunderstorms can form. The moist air can penetrate into the stratosphere to altitudes of more than 12.5 miles (20 km). These types of storms can produce violent updrafts and downdrafts. At the onset of precipitation, strong downdrafts develop. Falling precipitation reverses rising air columns by frictional drag, and eventually the thunderstorm will begin to dissipate. The strong cool downdrafts will eventually clear the region. New clouds can be seen forming in the upper left of the photograph.