How Do Tornadoes Form

How Do Tornadoes Form? A tornado is a violently column of air in contact with the earth and it extends between a cloud (often a thunderstorm cloud) and the surface of the earth. Winds in most tornadoes blow at 100 mph or less, but in the most violent and least frequent tornadoes, wind speeds can exceed 250 mph. Tornadoes a.k.a. twisters typically track along the ground for a few miles or for less than 100 yards wide, although rare monsters can remain in contact with the earth for over 50 miles and exceeds one mile in width. Several things must take place for the tornadoes and the thunderstorms, which the tornadoes are most associated with, to be formed. Abundant low level moisture is necessary, and a “trigger is needed to lift the moist air loft. Before thunderstorms develop, 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 thunder storm updraft is 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. A lower cloud base in the center of the photograph identifies and area of rotation known as a rotating wall cloud. This area is often, nearly rain-free. Note the rain in the background of the picture. Moments later a strong tornado develops in this area. Softball-sized hail and damaging “straight line” winds also occurred with this storm. Tornadoes usually result form a very large thunderstorm. When cold air and warm air combines, the cold air decreases while the warm air rises. This warm air eventually twists into a spiral, forming a funnel cloud. As the sky turns a very dark green color, the tornado begins its path of destruction.