Because the air moving down the leeward slope is dry.
warmth and evaporation
The windward side of a mountain is typically the west side of the mountain, receiving the various weather as weather moves west to east. The leeward side of a mountain opposes the windward side, making it the east side of the mountain, receiving little weather, blocking weather (rain) and warming air rapidly as it moves down this side of the mountain. The leeward side of mountains causes deserts, dry places, little rain, etc., for it releases warm air unto these places, and blocks weather (rain) from moistening them (I.E. Las Vegas, etc. on the eastern side of the mountain ranges).
because the leeward side of a mountain doesn't get any rain like on the westward side, also air drops in horse latitudes, and when air drops it causes a dry climate
When the wind encounters the windward side of a mountain, it is forced to rise. This causes it to cool due to decompression. If there is enough moisture in the air it will condense and fall as precipitation. When this happens, the moisture transfers heat to the air around it, causing it to cool at a slower rate than dry air would. When the air makes it over the mountain, it has lost a fair portion of its moisture. The dry air then warms up as it descends the leeward slope of the mountain. Because it does not contain condensed moisture to absorb that heat, it warms at a faster rate than the cooling it experienced when it was moist, meaning it will be warmer than it previously was at similar elevations.
Because the air moving down the leeward slope is dry.
The dry side of a mountain is called the leeward side. This is the side away from the wind. The dry area is known as a rain shadow.
warmth and evaporation
the change in pressure and dry air
The mountains are so high it shades the wind
The windward side of a mountain is typically the west side of the mountain, receiving the various weather as weather moves west to east. The leeward side of a mountain opposes the windward side, making it the east side of the mountain, receiving little weather, blocking weather (rain) and warming air rapidly as it moves down this side of the mountain. The leeward side of mountains causes deserts, dry places, little rain, etc., for it releases warm air unto these places, and blocks weather (rain) from moistening them (I.E. Las Vegas, etc. on the eastern side of the mountain ranges).
As it rises to get over the mountain it cools. As it cools it can no longer hold as much moisture in solution so this precipitates out of the air on the seawards side of the mountain. When it is over the mountain it sinks again and is warmed so it is now warm dry air and very little precipitation happens (there is a rain shadow).
because the leeward side of a mountain doesn't get any rain like on the westward side, also air drops in horse latitudes, and when air drops it causes a dry climate
Rain Shadow.
Rising air loses moisture as rain.
It's called a rain shadow.
Moisture laden air from the sea is forced upwards by mountain ranges where it condenses and falls as rain or snow on the windward side of the mountain. The now-dry air passes over the mountain range to the leeward side where a rain shadow desert has formed. See the diagram above