adiabatic expansion

In physics, an adiabatic process is a change within a system where energy is transferred only through work, not heat. This means the system is either well-insulated, or the process happens so quickly that heat transfer is negligible.1

A common example is the rapid expansion or contraction of a gas. When a gas expands, it does work on its surroundings. In an adiabatic expansion, this work is done at the expense of the gas's internal energy, causing it to cool down. This is known as adiabatic cooling. Conversely, when a gas is compressed adiabatically, its internal energy increases, leading to a rise in temperature.1234

This principle explains why higher elevations in the atmosphere are colder. As air rises, it expands due to lower atmospheric pressure, and this expansion causes it to cool. The rate at which temperature decreases with altitude due to this process is called the adiabatic lapse rate.34