Lazer umbrella

Stopping rain with a laser is one of those ideas that sounds totally reasonable, but if you—

While the idea of a laser umbrella might be appealing, it—

Ok. The idea of stopping rain with a laser is a thing we're currently talking about.

It's not a very practical idea.

First, let's look at the basic energy requirements. Vaporizing a liter of water takes about 2.6 megajoules,[1] and a big rainstorm might drop half an inch of rain per hour. This is one of those places where the equation isn't complicated—you just multiply the 2.6 megajoules per liter by the rainfall rate and you get laser umbrella power requirement (watts per square meter protected). It's weird when units work out so straightforwardly: