What indicates a potentially unstable atmosphere?

A potentially unstable atmosphere is indicated when the environmental lapse rate is somewhere between the dry and wet adiabatic lapse rates. In meteorology, the lapse rate refers to the rate at which temperature decreases with an increase in altitude. The dry adiabatic lapse rate is about 9.8 degrees Celsius per kilometer, while the wet adiabatic lapse rate is lower, around 5 to 6 degrees Celsius per kilometer, due to the presence of moisture in the air.

When the environmental lapse rate fits within this range, it suggests that the atmosphere is favorable for vertical movements of air. This condition allows for the rising of warm air, which can lead to convection, cloud formation, and potentially severe weather phenomena such as thunderstorms. Therefore, if the environmental lapse rate indicates that a parcel of air is warmer than the surrounding air at higher altitudes, this results in an unstable atmosphere conducive to storm development and turbulence.

Other scenarios, such as a negative environmental lapse rate (where temperature increases with altitude) or a constant lapse rate, typically indicate a stable atmosphere, where vertical movement of air is suppressed. An environmental lapse rate below sea level isn't applicable in the context of atmospheric stability and doesn't provide meaningful information about instability.