Can water air-condition your house?

What exactly is a swamp cooler, and why can it beat the heat in Arizona but leave you sweaty and betrayed in Houston? How can an air conditioner run on water, what does humidity have to do with its effectiveness, and could an icy new invention help prevent overloaded power grids? In the final installment of our air-conditioning series, Melissa and Jam explore evaporative cooling, ancient climate-control tricks, and some promising innovations for a hotter world. It turns out “It’s not the heat, it’s the humidity” is more scientifically accurate, and more annoying, than we’d like.