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How does rising air cool as it expands in Earth’s atmosphere?

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Engraved portrait of Rudolf Julius Emanuel Clausius, a bearded man in formal attire with sideburns, facing forward. — thermodynamics Rudolf Clausius (1822 - 1888) is considered one of the central founders of the science of thermodynamics.

As air rises in the Earth’s atmosphere, it undergoes a process known as adiabatic expansion. Because air is a poor conductor of heat, this process occurs without any significant heat exchange with the surrounding environment.12

As the air parcel ascends, it encounters lower atmospheric pressure, which allows it to expand. According to the first law of thermodynamics, the work done by the gas as it expands against the surrounding pressure must come at the expense of its own internal energy. As the internal energy of the air parcel decreases, its temperature drops.123

This cooling effect is quantified by the adiabatic lapse rate, which describes the rate at which the temperature of a rising air parcel decreases with altitude. If the air is dry, it cools at a rate of approximately 9.8 °C per kilometer (or 1 °C per 100 meters). If the air is saturated with water vapor, the release of latent heat during condensation causes it to cool more slowly.42