[psheets]

Larger systems can use cooling towers which leverage evaporative cooling. Also, arid climates can use swamp coolers to cool a space. They work on the same principal. When water evaporates, it pulls energy from the surrounding medium, causing the temperature to drop.

[maxerickson]

This article has a nice diagram and some explanation:

http://www.buildings.com/article-details/articleid/5757/titl...

In the discussed example, the water cooled system uses ~1/2 the energy of the air cooled system.

[abakker]

In CA, swamp coolers can be really great - http://www.homedepot.com/b/Heating-Venting-Cooling-Air-Condi...

I used one when I worked with a friend in LA on a car restoration project. They can generate a LOT of cooling very quickly as long as it is dry outside.

[maxerickson]

It's funny they show the northern Midwest in the maybe zone. When it is hot here, it is usually also quite humid.