LOS ANGELES — One of the driest spots on Earth — the Sahara desert — is increasingly responsible for snow and rain half a world away in the western United States, a study released Thursday found.
It’s no secret that winds carrying dust, soot and even germs make journeys through the upper atmosphere that can affect the weather thousands of miles away. Yet little is known about the impact of foreign pollutants on the West Coast, which relies on mountain snowmelt for its water needs.
Previous studies hinted these jet-setting particles might retard rainfall in the Sierra Nevada mountains in northern California by reducing the size of water droplets in clouds. But scientists who flew through storm clouds in an aircraft, measured rain and snow and analyzed satellite imagery found the opposite: Far-flung dust and germs can help stimulate precipitation.
The days with the most particles in the clouds were also “days when we see the most snow on the ground,” said study leader Kimberly Prather, an atmospheric chemistry professor at UC San Diego, whose study was published online Thursday in the journal Science.
