15.5: Review

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Supercell thunderstorms can create tornadic winds, straight-line winds, downbursts, lightning, heavy rain, hail, and vigorous turbulence.

Larger hail is possible in storms with stronger updraft velocities, which is related to CAPE. When precipitation falls into drier air, both precipitation drag and evaporative cooling can cause acceleration of downdraft winds. When the downburst wind hits the ground, it spreads out into straight-line winds, the leading edge of which is called a gust front. Dust storms (haboobs) and arc clouds are sometimes created by gust fronts.

As ice crystals and graupel particles collide within thunderstorm updrafts they each transfer a small amount of charge. Summed over billions of such collisions in a thunderstorm, sufficient voltage gradient builds up to create lightning. The heat from lightning expands air to create the shock and sound waves we call thunder. Horizontal wind shear can be tilted into the vertical to create mesocyclones and tornadoes.