Today we continue our Severe Weather Awareness Week topics with tornadoes. If you have lived in the Tennessee Valley for any amount of time, you are likely very familiar with tornadoes and the destruction they can cause.

How do tornadoes form? It all starts with wind shear in a storm. There are two different types of wind shear, directional and speed. Directional shear is when the wind direction changes with height, and speed shear is the change in wind speed with height. This shear, or change in the winds with height leads to a horizontal rotation of air in the atmosphere.

This horizontal rotation of air is then lifted into a vertical position by strong updraft winds in a thunderstorm. Then, the tornado begins to form, first with a wall cloud. Then, a funnel cloud will start to descend from the wall cloud to the ground. Once the funnel reaches the ground, it becomes a tornado.

Once on the ground, these violently rotating columns of air can cause a lot of damage. It is by this damage that they leave behind that the wind speed is estimated on the Enhanced Fujita (EF) scale. The Enhanced Fujita scale ranges on a scale from EF 0-5, where an EF-0 has winds of 65-85 mph, and an EF-5 has winds in excess of 200 mph.

Because tornadoes can cause so much damage on the ground, it is important to seek shelter from them. A basement or a storm shelter is the best place to seek shelter from a tornado. If a basement or storm shelter is not an option, then seek shelter on the lowest level of your home, in an interior room with no windows. This may be a bathroom or a closet in the most central part of your home. The idea here is to put as many walls between you and the outside world as possible. It is also a good idea to take something to cover your head, such as a bicycle helmet.

Next time severe weather threatens, be sure to stay tuned to The Weather Authority for the latest information and be ready to act.