Areas with dry climates on the leeward (downwind) side of mountain ranges are said to be located in the what

Areas with dry climate on the leeward (downward) side of mountain ranges are called rain shadows.

Explanation:

A rain shadow is a desert area where a dry region of land along the downward side of the mountain ranges. The area is dry due to the 'prevailing winds' towards the 'top of the mountains'. The protected side of the mountain is called down-wind side.

Example:

In North America - dry region of the 'cascade range' in Oregon and Washington, 'great basin of Nevada', Colorado Front range of Rocky region. In South America - dry region of Mendoza in Atacama desert, because of Andez mountains.