Hi, can someone from the higher echelons of Two weather explain to us mere mortal weather watchers what "breaking the cap" means
Cheers
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Originally Posted by: VIRTUAL STORMCHASER
The Cap is a layer of stable air aloft that prevents convection. It might be warm and humid at the surface, but this layer of stable air aloft prevents the warm and moist air from conectively rising above it to build into showers or thunderstorms. Typical of the situation we have now where High Pressure is dominant.
Think of it as a cap on a bottle of fizzy pop. You can shake it and get the liquid beneath pretty agitated, but as long as the cap is in place, it stays in the bottle.
This cap can be broken by heating or mechanical lift, but often the parameters are insufficient to break the cap under any circumstances. This is known as a being Stable. If the parameters are right, then given enough heating at the surface, or though convergence zones, orogrpahic lift, cooler air infilitrating aloft etc. then the Cap can be broken, which is known as Conditional Instability. Often the most violent thunderstorms occur with conditional instability, as all the energy accumulated beneath the cap is released at once when the cap is broken (the cap comes off the fizzy bottle).
EDIT: Beat me to it Neil. What he said as well.
Edited by user
17 July 2013 10:07:54
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Reason: Not specified
Ben,
Nr. Easingwold, North Yorkshire
30m asl