Enter the specific heat of the air or fluid being analyzed and the acceleration due to gravity to calculate the lapse rate.
Lapse Rate Formula
The following formula is used to calculate a lapse rate.
L = g / Cp
- Where L is the lapse rate (C/km)
- g is the acceleration due to gravity (9.81m/s^2)
- Cp is the specific heat of the gas at constant pressure
Lapse Rate Definition
A lapse rate is defined as the rate at which an atmospheric variable such as temperature changes with a change in altitude.
Why does lapse rate occur?
A lapse rate occurs because as a change in altitude occurs, a change in air density occurs. The less-dense air causes changes in pressure and temperature. The change in pressure is caused by the effect of gravity acting on the air.
Lapse Rate Example
How to calculate lapse rate?
- First, determine the acceleration due to gravity.
On earth this is equal to 9.81 m/s^2.
- Next, determine the specific heat.
Calculate the specific heat of the gas.
- Finally, calculate the lapse rate.
Calculate the lapse rate using the equation above.
A lapse rate is a measure of the change in temperature with respect to an altitude of a gas.