A tornado is a rapidly rotating column of air that involves a connection with the ground and the clouds above.  It usually involves the cumulonimbus clouds but occasionally a tornado may come from a cumulus cloud.  Tornadoes are often called twisters or cyclones.

Most tornadoes have wind speeds less than 110 miles per hour, around 25 feet in width, and travel only a few miles before leaving.  On the flip side and more rare, more serious tornadoes can reach wind speeds of over 300 miles per hour, extend two miles across, and cross dozens of miles before leaving.

Tornadoes are rated on the Fujita scale or Enhanced Fujita Scale from F0 / EF0 to F5 / EF5 which is based on the amount of destruction created.  The Tri-State (Missouri, Illinois and Indiana) tornado holds the record for the longest path length at 219 miles, the longest time on ground at 3.5 hours, and the fastest forward speed at 73 mph.  It is also the deadliest tornado on record with 695 people killed.