Convective overshoot

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Convective overshoot is the phenomenon of convection carrying material beyond an unstable region of the atmosphere into a stratified, stable region. Overshoot is caused by the momentum of the convecting material, which carries the material beyond the unstable region.

[edit] Overview

Main article: Overshooting top

One example is thermal columns extending above the top of the equilibrium level (EL) in thunderstorms: unstable air rising from (or near) the surface 'should' stop convecting at the EL (which is near the tropopause) spreading out as an anvil cloud; but in the event of a strong updraft, unstable air is carried past the EL as an overshooting top or dome. A parcel of air will stop ascending at the maximum parcel level (MPL). This overshoot is responsible for most of the turbulence experienced in the cruise phase of commercial air flights.

Another example of convective overshoot is at the base of the convection zone in the solar interior. The heat of the Sun's thermonuclear fusion is carried outward by radiation in the deep interior Radiation zone and by convective circulation in the outer convection zone, but cool sinking material from the surface penetrates farther into the radiative zone than naive theory would suggest. This affects the heat transfer rate and the temperature of the solar interior.