Submitted: May 23, 2008 - If you've ever walked the New York City streets in July, you've experienced the misery of this phenomenon. Why do cities heat up like furnaces while surrounding areas remain cooler?

As the name implies, the effect makes cities into islands of heat. According to the U.S. Environmental Protection Agency, temperatures in U.S. cities can get as much as 10 degrees Fahrenheit higher than their…