Dry Adiabatic Lapse Rate Calculator

When to Use Each Variable

• Solve for Lapse Rate — when you know gravity and specific heat and need the temperature drop per unit altitude — e.g., comparing lapse rates on different planets.
• Solve for Gravity — when you have a measured lapse rate and specific heat — useful for back-calculating effective gravity from atmospheric sounding data.
• Solve for Specific Heat — when you know the lapse rate and gravity — e.g., estimating the heat capacity of an alien atmosphere from descent probe data.
• Solve for Temperature at Altitude — when you know the surface temperature and lapse rate and need the air temperature at a given height — e.g., predicting icing conditions for aircraft.
• Solve for Surface Temperature — when you have a temperature reading at altitude and want to extrapolate back to the ground — e.g., correcting weather station data.
• Solve for Altitude — when you know the surface and upper temperatures and need the elevation of that temperature — e.g., estimating the freezing level.

Key Concepts

The dry adiabatic lapse rate (DALR) describes how unsaturated air cools as it rises and expands without exchanging heat with its surroundings. It equals g/cp, approximately 9.76 degrees C per kilometer on Earth. Once air becomes saturated, latent heat release slows the cooling, and the moist adiabatic lapse rate (about 5-6 degrees C/km) applies instead. The DALR is a key factor in assessing atmospheric stability.

Applications

• Aviation: predicting temperature at cruising altitude and assessing icing risk
• Meteorology: determining atmospheric stability by comparing the DALR to the actual environmental lapse rate
• Wildfire management: estimating how quickly rising smoke plumes cool, which affects plume height and smoke dispersion
• Mountain weather forecasting: predicting summit temperatures from valley observations

Common Mistakes

• Applying the dry rate to saturated (cloudy) air — once condensation begins, the moist adiabatic rate is lower
• Confusing lapse rate with temperature inversion — an inversion means temperature increases with altitude, not decreases
• Using inconsistent units — mixing degrees C/km with degrees F/ft without converting