mountains

[beam me up]

why does one side of a mountain range sometimes have significantly less precipitation than one other side?

[Clanad]

Throughout the world, but especially here in the U.S., the weather patterns are dominated by the upper winds and tend to move from northwest to southeast. In doing so, the winds along the surface moving upslope... that is up the mountain ranges releases the moisture due to adiabatic cooling in the form of either snow or rain. As the system moves eastward, the weather pattern now has less moisture to release and the eastern slopes are often "shaded'... that is the upper winds take the moisture that's left on beyond that side of the mountain. An oversimplified description, but basically the same throughout the world...

[commoner]

LOL.......Clanad I love the way you say "an oversimplified description"

I think an oversimplified answer would perhaps be to merely say......caused by the prevailing winds....<G>

[Clanad]

Problem is, commoner,, localized, but large geographical areas can produce significant amounts of moisture with prevailing winds that are upslope in nature. That is, certain weather patterns can cause winds to flow in the opposite direction to that normally experienced, in which case the rain/snowfall will be on the eastern sides of the mountains. Here in the western U.S., in late February through May, we get upslope conditions that cause some of the heaviest snowfall of the year. This can extend all along the Front Range of the Rocky Mountains...