There are rivers moving across the sky that can carry more water than some of the world's largest rivers on the ground.

They aren't made of flowing water you can see.

They're enormous corridors of concentrated moisture traveling through the atmosphere—and when they arrive, they can completely transform the weather below.

The Rivers in the Sky That Can End a Drought or Cause a Disaster explores the phenomenon known as atmospheric rivers and the incredible amount of water vapor they can transport across continents.

Atmospheric rivers form when large amounts of moisture are gathered in the atmosphere and carried by strong winds.

When one reaches land and encounters mountains or other weather systems, that moisture can be forced upward, cool, and fall as rain or snow.

The results can be dramatic.

An atmospher ...