9781422269565

The long, flat, dark cloud is a wall cloud. Look at the size of it in relation to the house pictured below it!

The most destructive tornadoes originate from supercells, which can also produce severe winds, lightning, flash floods and damaging hail. Tornadoes generated from a supercell thunderstorm are definitely the most common and the most dangerous, but only about 20 percent of all supercell

thunderstorms produce a tornado. Non-Supercell Tornadoes

Some tornadoes form from a long line of strong thunderstorms called quasi-linear convective systems (QLCS). These tornadoes are weaker and shorter-lived than supercell tornadoes, and tend to occur late at night or early in the morning. The long line of strong thunderstorms is called a squall line. These thunderstorms usually form east of the Rocky Mountains in the United States, and usually form during springtime when atmospheric conditions are right. One common type of squall line is the bow echo which resembles an arched bow of storms.

10

Facing the Weather: Tornadoes