Image of San Francisco taken on August 16th. Image by NASA. Click to enlarge.
The short answer to why San Francisco, California is foggy? The Pacific Ocean’s marine layer. A new image by NASA’s Earth Observing-1 satellite shows the marine layer—cool, heavy air produced by a colder ocean surface meeting warmer air—encroaching on the metropolis. Western winds push the marine layer over the city, which brings dense cloud cover over the city, and often engulfs buildings, bridges, and people in fog. Fog is defined as suspended droplets that limit visibility to 1,000 meters (3,000 feet), anything less dense is technically considered mist.
This weather pattern is most common in the summer due to shifts in the California Current which brings an upwelling of frigid, deep water to the surface of the ocean. Once the cold water meets the warmer air, the marine layer is formed, blanketing San Francisco in its iconic fog.
Related articles
Scientists testing anti-fungal bacteria on diseased frogs in California
(07/23/2012) Researchers are treating tadpoles in Kings Canyon National Park with a bacteria they hope will provide immunity to an infamous fungal disease, reports the San Francisco Gate. The bacteria could be key not only to saving California’s mountain yellow-legged frog (Rana muscosa), which is listed as Endangered by the IUCN Red List, but also frog species around the planet, many of which have been decimated by the chytrid fungal disease.
Marijuana farms poisoning carnivorous fishers in California, finds study
(07/13/2012) An illegal pesticide used by marijuana growers to kill rodents is poisoning weasel-like fishers in California, reports a new study published in the journal PLoS ONE.
San Francisco bars officials from buying Apple computers for city business
(07/11/2012) Employees at San Francisco agencies will no longer be able to buy Apple products for official city business due to the computer giant’s decision to pull out of a green certification scheme for consumer electronics, reports the Wall Street Journal.
California cap-and-trade law spurs U.S. forest carbon projects
(02/15/2012) Now that California’s carbon market has arrived, an Australian-based company that specializes in forest carbon offsets has jump started two forest projects with private landowners in the western U.S. The new company, Forest Carbon Partners, will make the projects available as carbon offsets for California polluters.
California sets tough new clean car standards
(01/30/2012) The U.S. state that takes climate change most seriously—California—has unanimously approved new rules dubbed the Advanced Clean Cars program to lower carbon emissions, reduce oil dependence, mitigate health impacts from pollution, and save consumers money in the long-term. According to the new standards, by 2025 cars sold in California must cut greenhouse gas emissions by 34 percent and smog emissions by 75 percent. The program will also require 15.4 percent of all cars sold in California to be zero or near-zero emissions by 2025.