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Pacific Air Conditioning: Earth Image of the Week July 30, 2010
Satellite Image of California coastal fog
Only the highest peaks of the Sierra Nevada and Cascade Range can still be seen to have a capping of snow from the heavy dumping most areas recieeved over the past winter.
California’s coastal strip usually escapes the “dog days” heat of summer each year thanks to a natural air conditioning it receives from being next to the Pacific.

A blanket of fog often stretches along much of the coast and adjacent coastal valleys each night from May through August. As the heat of the day begins to warm the interior each morning, it also gradually dissipates the fog back to near the Pacific beaches by afternoon.

This effect creates a variety of microclimates with temperatures ranging from the upper 50s Fahrenheit at the coast to the 90s and even well over 100 degrees far inland.

When the image to the right from NASA’s Terra satellite was taken at 11:55 a.m. Pacific Daylight Time on Friday, July 23, 2010, coastal fog and low cloudiness were present from the Oregon border southward to Baja California.

The enlarged version of the image reveals that fog was lingering at midday for a few miles inland across Monterey Bay. Growers in this area take advantage of the temperate summertime conditions to raise such cool-weather crops as artichokes, peas and strawberries, which can’t be grown elsewhere at this time of year.

The high temperatures for July 23 that are plotted over the satellite image show how the coastal influence is weaker on a location the farther inland it is. While highs were only in the 70s along the coastal strip from Los Angeles to San Diego, Las Vegas and Yuma have maximum temperatures of 107 and 110 degrees respectively.

Sacramento often receives a sea breeze from San Francisco Bay late each summer afternoon and evening, resulting in moderated daytime temperatures and far more confortable overnight conditions than areas without an ocean influence.

NASA MODIS Rapid Response System