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] Thunderstorms

One example is thermal columns extending above the top of the troposphere in thunderstorms: unstable air rising from the surface 'should' stop ascending at the tropopause spreading out as an anvil cloud, but its momentum carries it up into the stratosphere as an overshooting top or dome. This overshoot is responsible for most of the turbulence experienced in the cruise phase of commercial air flights.

[edit] Stars

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 radiative 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.