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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:
- 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 |
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Atmospheric Stability Calculator
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