Flashcards in Chapter 18 Deck (14):
Why do we care about thunderstorms?
they are a water resource, they redistribute heat and moisture in the atmosphere, and they cause lots of property damage and sometimes injuries/deaths.
What elements are required for thunderstorm formation
-A source of moisture
-A conditionally unstable atmosphere
-A mechanism to trigger the thunderstorm updraft
What must occur for a thunderstorm to be considered a severe thunderstorm?
-Hail >3/4" diameter
-Gusts of 50 knots or greater
Three stages of an airmass thunderstorm?
1. Cumulus stage - Warm Buoyant plume of rising air
2. Mature stage - Precipitation begins to fall from the thunderstorm
3. Dissipation Stage - The downdraft dominates the storm
Where do airmass thunderstorms typically form?
Deep within airmasses...Away from large scale fronts
What triggers an airmass thunderstorm?
Surface heating, lifting by mountains, or outflow from neighboring T-storms
What are the winds like in the environment where airmasses thunderstorms form?
Little to no vertical shear
The flat top of a thunderstorm that forms as the thunderstorm updraft hits the tropopause and spreads out horizontally
What are the prominant features of a Airmass Thunderstorm?
Do thunderstorms with wind shear last longer?
What is a Mesoscale Convective System?
Mesoscale means a few to a few hundred kilometers (one t-storm to large groups of t storms)
How does the cold pool form?
Rainfall evaporation cools mid to upper troposphere air, which sinks to surface and forms a cold pool
What is a bow echo?
is a line, that turns into bow shapw with twics on the top, the big part of the twisting