We live near the bottom of a steep south facing slope on a mountain range that runs east to west. During the hottest parts of the summer, the air at the top of the mountain cools significantly as the sun goes down, then sinks and falls down the slope, bringing a very welcome cool breeze at a time of year when it is exceptionally welcome.
When we realised that this was a regular occurence, we put a window in the back, north facing wall of the house so that we could open it the moment the outside air cooled to below the temperature indoors. When all the windows in the house are open, the cool air rushes straight into the back of the house and carries hot air out through the front. Putting that cool breeze to work to cool the interior of the house overnight means that the house takes longer to warm up during the day allowing us to cope with the hot summers here with no air-conditioning and using almost exclusively passive methods to keep the temperature within comfortable limits.
My other half tells me this sort of wind is known as a
katabatic wind.
Here's an image from the wikipedia page to show how it works...
