Atmospheric Stability

Atmospheric Stability

To determine the stability of the atmosphere, we compare the Parcel Temperature to the Environmental Temperature. 

• When the parcel is colder than the surrounding air, it is stable.

• When the parcel is warmer than the surrounding air, it is unstable. 

Lapse Rates

• Dry Adiabatic Lapse Rate (DALR): +10°C/km

• Moist Adiabatic Lapse Rate (MALR): +6°C/km

• Environmental Lapse Rate (ELR): Calculated by using the vertical temperature data of the atmosphere provided on a sounding. 

• Dewpoint Lapse Rate: +2°C/km

Absolutely Stable (ELR < MALR)

• A parcel of air cannot rise on its own. It must be lifted.

Absolutely Unstable (ELR > DALR)

• A parcel of air can rise freely on its own. 

Conditionally Unstable (MALR < ELR < DALR)

• A parcel can be stable or unstable. It will depend on whether the parcel is dry or saturated. 

Neutrally Stable (ELR = DALR or ELR = MALR)

• A parcel will not rise or sink