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Tornado – what could go wrong?
Often times, there are one or more things that could inhibit tornado formation in an otherwise favorable atmosphere. Despite the high number of tornadoes we get in the U.S. each year, tornadoes are very sensitive to the surrounding environment. One little detail can turn a potential tornado outbreak into a run-of-the-mill line of storms, or even a “blue sky bust.” The Cap We keep coming back to this atmospheric cap (see the A Forcing Mechanism section to review), but it’s just that important of a feature. A cap is a section of the atmosphere where temperatures briefly increase with height, which is usually in the middle levels of the atmosphere. This cap creates a stable layer that unstable air below it has to try to break through in order to create a storm. The strength of the cap can be the difference between blue skies and a mile-wide wedge. There are three main ways to break the cap:- The first one is to heat and mix the lower levels of the atmosphere to the point where the heat from the surface creates enough buoyancy and momentum for a pocket of air to rise through the cap.
- The second way is to get a forcing mechanism, such as a cold front, to forcibly lift a pocket of unstable air through the cap until the air can get to a point where it can rise freely on its own.
- A common third way to erode the cap is from the top down, with an upper-level trough bringing cooler air into the capped portion of the atmosphere.