The Dry Adiabatic Rate (DAR) and the Wet Adiabatic Rate (WAR) are two important concepts in meteorology that describe how air temperature changes as it rises or descends in the atmosphere. Here’s how they differ:
Dry Adiabatic Rate (DAR): The DAR occurs in unsaturated conditions, meaning the air does not contain enough moisture to reach the dew point. When air rises, it expands and cools at a rate of approximately 10°C per 1000 meters (5.5°F per 1000 feet). This cooling happens because the air is not saturated, and no condensation occurs to release latent heat.
Wet Adiabatic Rate (WAR): The WAR occurs in saturated conditions, where the air contains enough moisture to reach the dew point. As the air rises, it cools at a slower rate, typically around 6°C per 1000 meters (3.3°F per 1000 feet). This slower cooling rate is due to the release of latent heat during condensation, which partially offsets the cooling caused by expansion.
In summary, the key difference between DAR and WAR is the moisture content of the air. DAR applies to unsaturated air, while WAR applies to saturated air. This difference in moisture content leads to different rates of temperature change as the air rises or descends in the atmosphere.