Explanation:

Orographic Precipitation

Rainfall in the doldrums is of the nature of Orographic precipitation. Orographic Rainfall is a form of precipitation where warm moist parcels of air from an ocean, Sea or lake rises over a barrier such as a mountain. When the saturated air mass comes across a mountain, it is forced to ascend and as it rises, it expands (because of fall in pressure); the temperature falls, and the moisture is condensed. This type of precipitation occurs when warm, humid air strikes an orographic barrier (a mountain range) head on. Because of the initial momentum, the air is forced to rise. As the moisture laden air gains height, condensation sets in, and soon saturation is reached. The surplus moisture falls down as orographic precipitation along the windward slopes.