What is the cooling rate for dry air?

The cooling rate for dry air is known as the dry adiabatic lapse rate, which is approximately 3 degrees Celsius for every 1000 feet of altitude gained. This rate applies to unsaturated air and reflects how the temperature of the air decreases as it ascends due to the decrease in pressure at higher altitudes.

As air rises, it expands due to lower atmospheric pressure, which causes the air to cool. The specific rate of 3 degrees Celsius per 1000 feet is a standard value used in meteorology and aviation to help pilots understand temperature changes with altitude, aiding in weather prediction and understanding aircraft performance in different atmospheric conditions.

The other rates provided do not accurately represent the cooling behavior of dry air under adiabatic conditions. For instance, while the rate of 2 or 4 degrees per 1000 feet could be relevant under different scenarios (like moist air cooling at the moist adiabatic lapse rate or specific atmospheric conditions), the standard and widely accepted rate for dry air is indeed 3 degrees Celsius per 1000 feet. Understanding this principle is vital for pilots in planning flights and making altitude-related decisions.