The extreme climate of Death Valley is attributable to its location onthe leeward (downwind) side of the Sierra Nevada Mountains in centralCalifornia. Air that has been warmed and moistened by its passage overthe Pacific Ocean is driven up over the Sierras as it is carriedeastward by the prevailing southwesterly winds of the northernmid-latitudes.
As the air rises up over the mountains, it expands and cools,triggering condensation that forms clouds and causes precipitation onthe windward (west facing) slopes. At the same time, the latent heatstored in the water vapor in the air is released by the condensationprocess, adding measurable heat to the air As the now warmer and drierair continues its eastward journey over the peaks and begins itsdescent into the valleys on the leeward side of the range, itstemperature rises as it is compressed under the higher atmosphericpressure of the lower elevations. The fact that Death Valley lies belowsea level causes even more compression of the descending air, creatinga very hot and dry “rain shadow desert” in Death Valley.