Air is of air parcels tend to remain at the same altitude or, if displaced vertically, tend to return to their original altitude. The other condition occurs if, once displaced vertically, air parcels continue to move away from their original altitude.

Stable

Explanation:

when air parcel is warmer than the surrounding environment, it becomes buoyant and forced rise upward or move by mountains or a front for their temperatures to cool down to the dew point temperature,

When this occurs, Air is said to be stable when air parcel that are displaced by rising or sinking tend to return to their original position.

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