Steepness of the Mountain

The steepness of a mountain or hill slope decides what happens to rainfall once it lands: on steep terrain, rain tends to run off quickly rather than soak in, so the ground loses water fast and the resulting water deficit, combined with rapid erosion of topsoil, leaves steep slopes with generally poor vegetation. Plains and valleys, by contrast, drain surface water much more slowly and retain far more moisture in the soil, which is why they typically support rich, dense vegetation. Slope also interacts with wind and rainfall direction at a larger scale: the windward face of a coastal hill or mountain range, which directly intercepts moisture-laden winds coming off the sea, receives heavy rainfall and grows rich vegetation, while the leeward face o …