Where is the LCL (lifting condensation level) on the leeward side of and why?

The Lifting Condensation Level (LCL) is the altitude at which an air parcel, when lifted, reaches saturation and condensation begins. It is typically lower on the leeward side of a mountain range compared to the windward side.

To understand why the LCL is lower on the leeward side, we need to consider the process of orographic lifting. When air encounters a mountain, it is forced to rise, and as it moves up the windward side, it cools adiabatically (cooling due to expansion as it rises). As the air continues to rise on the windward side, it reaches its dew point temperature, and condensation occurs, forming clouds and precipitation.

Now, as the air moves over the summit and descends on the leeward side, it undergoes adiabatic warming (warming due to compression as it descends). As the air descends, it warms at a rate of approximately 10 degrees Celsius per 1000 meters (known as the dry adiabatic lapse rate). This warming causes the air parcel to become drier, as the capacity of air to hold moisture increases with temperature.

Therefore, as the air descends on the leeward side, it becomes warmer and drier, and its relative humidity decreases. Consequently, the LCL on the leeward side is lower compared to the windward side. The lower LCL means that the air needs to be lifted to a lesser altitude for condensation to occur, resulting in fewer clouds and less precipitation on the leeward side of the mountain range.