Re: A question about Katrina and Now
Posted by CX on 8/25/2016, 7:43 pm
The Sahara is key. You'll see it mentioned a fair bit as SAL - Saharan Air Layer. It's a mechanism that suppresses convection. It's a very hot and dry air mass that, when pushed out over the ATL, sits above the marine layer, which tends to be far more humid and cool. So not only does the SAL suppress convection because it is too dry, but it acts like a convective 'cap'. Generally the atmosphere cools with height, which allows for condensation - the formation of clouds, etc. When an air layer is too warm, there is no condensation (or less condensation) because there is less cooling with height, which means thunderstorms cannot form en masse to create the movement of air necessary for tropical cyclogenesis.
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A question about Katrina and Now - Mark in PC Beach, 8/25/2016, 2:41 pm
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