Yazd is famous of the air-cooling shafts (badgirs) over the mud-brick build­ings.

Windcatcher (wind tower, wind scoop, badgir / بادگیر‎ ) is a traditional Persian architectural element to create natural air-conditioning system and passive cooling in buildings.
Windcatchers are widely used in Iran, North Africa and in the West Asian countries around the Persian Gulf, and have been for the past three thousand years.

Taller windcatchers catch higher winds. Higher winds blow stronger and cooler (and in a different direction) Higher airs are also usually less dusty.

http://en.wikipedia.org/wiki/Windcatcher