Atmospheric Stability Calculator

Introduction : This calculator calculates the type of stability, given the observed (or environmental) lapse rate. We can compare this lapse rate for any given day to the "standard" dry and moist lapse rates shown in the table below. Based on a comparison of these values, we can determine how stable the atmosphere might be.

In this calculator, you have one input value:

  1. Observed (environmental) lapse rate, in degrees C per km of height

Test Condition Atmospheric Stability
Observed lapse rate < dry adiabatic lapse rate Stability (stable atmosphere)
Observed lapse rate < moist adiabatic lapse rate Absolute stability
Observed lapse rate > moist adiabatic lapse rate Instability
Observed lapse rate > dry adiabatic lapse rate Absolute instability
Observed lapse rate < dry adiabatic lapse rate AND
Observed lapse rate > moist adiabatic lapse rate
Conditional instability
Observed lapse rate = dry adiabatic lapse rate Neutral stability

For your reference, this table shows a variety of lapse rates in different units.

Name of lapse rate Rate in F/ft Rate in C/km
Dry adiabatic lapse rate 5.5oF/1000 ft. 9.8oC/km
Moist adiabatic lapse rate 3.2oF/1000 ft. 5.8oC/km
Dewpoint adiabatic lapse rate 1.0oF/1000 ft.
3.2oF/1000 ft above the LCL
1.8oC/km
Temperature-dewpoint approach rate 4.5oF/1000 ft. 8.0oC/km
Normal temperature lapse rate 3.5oF/1000 ft. 6.5oC/km

Atmospheric Stability Calculator


Input Values:

Observed temperature lapse rate (in degreesC/km)

Results:

Stability condition