Anna Answers: How do tornadoes form?

Weather Wisdom

Question: How do tornadoes form? Will landmarks or buildings protect me from them forming?

Answer: No, tornadoes can form anywhere where the ingredients are present! The key ingredients are instability and shear. According to the National Weather Service, instability is present when at the surface there is warm and moist air and wind shear is a change in wind speed and or direction with height

Let’s start by defining a tornado. A tornado is a rotating column of air that originates from a thunderstorm and comes in contact with the ground. The air within the tornado needs to twist.

For the winds to twist there needs to be wind shear, the winds at the surface need to be a different speed or direction than the winds aloft. If the air at the surface is twisting from the shear and there is a thunderstorm updraft, then the air is forced upwards through the updraft. When it is forced up it will then begin to spin. 

When the spinning of the updraft and there is enough instability present than a tornado can form. The spinning taking place is then stretched upwards. When it is stretched upwards it spins faster. This is called vorticity. It can be best explained is if an ice skater is spinning on the ice and brings their hands closer to them it will cause them to spin faster.  This creates the wall cloud. From the wall cloud, the rotating column of air builds downwards and creates the funnel cloud. If the funnel cloud touches the ground it is a tornado.

When the ingredients are present a tornado can form anywhere. No land formations such as a mountain, hill, or lake or buildings such as cities are immune from a tornado forming there if the ingredients for the tornado are present and come together.

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