Did you know that there are two songs that poetically exaggerate the lack of rain in southern California?

One was written by two British guys in 1972 and the chorus is: “It never rains in California, but girl don't they warn ya. It pours, man it pours." The other is a 90’s R&B hit by Tony! Toni! Tone! which immediately opens with the famous line: “It never rains in southern California.”

Besides being boring songs about other things, the former about how Hollywood is cruel town and the other about a relationship, they are factually inaccurate. It rains and sometimes it even snows in the Golden State!

A group of researchers led by NOAA and UCSD found that dust and biological aerosols (composed of: sea salt, bits of soot and other pollution or biological material like bacteria, viruses, pollen, and plants) from far-flung exotic locales like the Sahara desert impact the precipitation levels in the Sierra Nevada.

Scientists know that our planet’s winds are capable of carrying aerosols like dust, at altitudes above 5,000 meters or 16,400 feet from continent to continent. The Scripps Institute of Oceanography pointed to an unrelated study from 2006 that discovered Asian dust made a complete circuit around the planet in about two weeks.  

But a California Energy Commission funded project called the CalWater field campaign is likely the first that has been able to link the snow in the Sierra to the hot dusty stuff of the Sahara.

"We were able to show dust and biological aerosols that made it from as far as the Sahara were incorporated into the clouds to form ice, then influenced the formation of the precipitation in California," said Jessie Creamean a postdoctoral associate at NOAA's Earth System Research Laboratory in Boulder, Colorado.

Cremean and colleagues conducted the fieldwork under Kimberly Prather, who holds appointments at Scripps Institution of Oceanography and the Department of Chemistry and Biochemistry at UCSD. Prather was the study’s lead author.

"To our knowledge, no one has been able to directly determine the origin of the critical aerosols seeding mid-level clouds which ultimately produce periods with extensive precipitation typically in the form of snow at the ground," Cremean added.

Dust and biological aerosols will often act as ice nuclei and initiate the freezing of water vapor and water droplets in clouds that create rain or snow. Researchers found this often enhanced the precipitation-forming processes in the Sierra Nevada instead of having the opposite affect, interrupting precipitation, which was what previous research had indicated.

Most of the data was collected with a series of instruments including aerosol time-of-flight mass spectrometers (ATOFMS), which Prather helped develop, during winter storms in February of 2011.

Data from one ATOFMS aircraft-mounted unit indicated at least some of the dust and bioparticles detected on flights through Sierra Nevada storm clouds were in the skies over Oman 10 days earlier and were likely to have started their life in the Sahara a few days before that. These particles mixed with other aerosols from deserts in China and Mongolia before floating over the Pacific Ocean to finally “seed” the clouds in California’s 400 mile long mountain range.

So the next time it rains in California you can thank Asia.