1.2.3.4. Equilibrium level (‚anvil level‘)

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  • Author: SW101

Recap

The equilibrium level is the limit of upward development of an updraft. This is the level at which the rising air in the updraft cools down to the temperature of the surrounding air. Thus the air in the updraft looses its positive buoyancy and stops rising. The height of the equilibrium level depends on the temperature of the air in the rising updraft and the temperature of the surrounding air (i.e. on the available convective potential energy of the rising air). Weak updrafts have low equilibrium levels, while stronger updrafts have higher equilibrium levels.

In thunderstorms the shape of the Cumulonimbus cloud depends on the equilibrium level. When the equilibrium level is not defined by a temperature inversion, the rising updraft forms a wispy, fibrous icy top, becoming a Cumulonimbus capillatus. When the equilibrium level is defined by a temperature inversion, it acts as a ceiling and the updraft spreads into ana anvil shape, becoming a Cumulonimbus capillatus incus. Updrafts in strong thunderstorms usually rise all the way up to the tropopause.

On to some examples.