What Causes Tornadoes, and How Do They Form? [VIDEO]

Having lived in Tulsa and Oklahoma City, I'm no stranger to tornadoes.With the devastating tornado on Moore Oklahoma yesterday, a brief explanation coupled with a video might help those who wonder how tornadoes form in the first place.

Most tornadoes form from thunderstorms. You need warm, moist air from the Gulf of Mexico and cool, dry air from Canada. When these two air masses meet, they create instability in the atmosphere. A change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere. Rising air within the updraft tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.

The video describes the actual formation of a tornado.