Warm air near the ground and cold air above. Unstable air can lead to billowing clouds and storms.

Air that does not resist vertical displacement. Thunderstorms are easily created in an unstable atmosphere.

air that rises easily and can form clouds and rain.

Air that is warmer than its surroundings and as such tends to rise, leading to the formation of clouds and possibly precipitation.

generally, air which will continue to rise and accelerate when briefly forced upward

Air with temperature differences that encourage the formation of convection currents that can produce clouds and precipitation.

Air that does not resist vertical displacement. If it is lifted, its temperature will not cool as rapidly as the surrounding environment and so it will continue to rise on its own. See also Absolute Instability.

Air in which static instability exists. This condition is determined by the vertical gradients of air temperature and humidity.