Tornadoes - what are they?

Tornadoes are one of Mother Nature's most destructive storms, usually occurring during the spring and summer months.
Tornadoes (sometimes called twisters) are violently rotating columns of air extending from a thunderstorm in the air to the ground that can cause tremendous property destruction, injury and loss of life. According to FEMA (Federal Emergency Management Agency) the most violent tornadoes ever recorded in the United States have registered rotating wind speeds of more than 250 miles-per-hour and created damage paths in excess of one mile wide and 50 miles long.