Ordinary thunderstorms last about one hour. The precipitation associated with them is rain and occasionally small hail. An ordinary thunderstorm cloud can grow up to 12 kilometers high.

Severe thunderstorms are really dangerous. They are capable of producing baseball-sized hail, strong winds, intense rain, flash floods, and tornadoes. Severe thunderstorms can last several hours and can grow 18 kilometers high. Several phenomena are associated with severe thunderstorms. These include the gust front, microburst, supercell thunderstorm, and the squall line.

A supercell thunderstorm is a huge rotating thunderstorm. It can last for several hours as a single entity. These storms are the most likely to produce long-lasting tornadoes and baseball-sized hail.

A squall line consists of several thunderstorms banded together in a line. They are generally associated with a cold front. Squall lines can be just as severe as a supercell thunderstorm.

Tornadoes form from severe thunderstorms. They have a very high energy density which means that they affect a small area but are very destructive to that area. They also don't last very long which makes it hard to learn about them. Since they're hard to study, they're also hard to forecast. People know even less about tornadoes, which is why there are a lot of different myths that aren't true.

Tornadoes can occur anywhere in the world. About 75% of them happen in the United States, most in an area know as Tornado Alley. There are also some other interesting facts about tornadoes.