Straight Line Wind Damage

      100 year old oak tree brought down Thursday.

The severe weather we saw on Thursday came from straight-line or microburst winds.  These winds are a result of air being rapidly accelerated down from the mid and upper parts of the thunderstorm to the ground.  The downflow can occur due to several factors: by air being pulled down by rain or hail, by the increases in air density as the air is cooled by rain and by the cooling produced with melting ice crystals.  These three factors, if strong enough, can create massively intense and sudden downward movements of air.  Most microbursts last only five to 15 minutes.   

An interesting note: These winds used to cause quiet a few plane crashes in the 60s and 70s.  For a pilot getting caught in a downburst wind, the plane would experience a sudden headwind followed by a strong tailwind a few moments later.  An inexperienced pilot would accelerate trying to slow the plane down, but the tailwind would come right after that causing the plane to lose the air flow across the wings (the critical principle to maintain flight.)  Consequently, the sudden loss of air moving across the wings would literally cause the aircraft to drop out of the air.   The best way for a pilot to stay in the air is to increase speed as soon as the abrupt drop in airspeed is noticed.  This will allow the aircraft to remain in the air when traveling through the tailwind portion of the microburst.  Forecasting of downburst winds is a lot better today than it was in the 70s.  Planes can completely avoid these type of storms.   

To view past weather quiz answers click here:

Past Weather Quiz Answers

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