Scientists to eye sky 'rivers' during California storm

Yes, there are rivers up in the sky, and they're made from water vapor rather than liquid. Made visible by clouds, these ribbons of vapor extend thousands of miles from the tropics to the western U.S. and provide the fuel for massive rainstorms in California, such as the one forecast to drench northern parts of the state through the weekend... Each year, the rivers provide up to half of California's precipitation, and the severe drought the state is experiencing is the result of a dearth in the weather phenomenon...Conversely, a strong atmospheric river event can cause large floods. One study found atmospheric rivers were responsible for every flood of northern California's Russian River in a seven-year period.