Severe Storms 20.3

Thunderstorm

• A storm produced by a cumulonimbus cloud and always accompanied by lightning and thunder; it is relatively short duration and usually accompanied by strong wind gusts, heavy rain, and sometimes hail.

Tornado

• A small, very intense cyclonic storm with exceedingly high winds.

Hurricane

• A tropical cyclonic storm having winds in excess of 119 kilometers per hour.

Eye Wall

• The doughnut-shaped area of intense cumulonimbus development and very strong winds that surrounds the eye of a hurricane.

Eye

• A zone of scattered clouds and calm averaging about 20 kilometers in diameter at the center of a hurricane.

Storm Surge

• The abnormal rise of the sea along a shore as a result of strong winds.

Key Concept

• A thunderstorm is a storm that generates lightning and thunder. Thunderstorms frequently produce gusty winds, heavy rains, and hail.

Key Concept

• Thunderstorms form when warm, humid air rises in an unstable environment.

Key Concept

• Tornadoes are violent windstorms that take the form of a rotating column of air called a vortex. The vortex extends downward from a cumulonimbus cloud.

Key Concept

• Whirling tropical cyclones that produce winds of at least 119 kilometers per hour are known as hurricanes in the United States. Hurricanes develop most often in the late summer when water temperatures are warm enough to provide the necessary heat and moisture to the air.