These cooled air masses then flow over the regions in their path. The topography, or features of the land also influences the climate. The amount of precipitation in a region is affected by mountain ranges in that area. Mountains cause air to rise. Rising air becomes less dense allowing the condensation of water.
Air moving down the other side of the mountain becomes more dense.
Sinking air does not produce precipitation. The leeward side, or side facing away from the wind, receives much less precipitation. Winds can greatly affect the amount of precipitation an area receives depending on the amount of moisture they are carrying. These prevailing winds can move air masses from the ocean onto a continent bringing moisture onto the continent. Or prevailing winds may move air masses from continent to the ocean, moving drier air from the continent.