Tule fog across California’s Central Valley
Today’s Image of the Day from NASA Earth Observatory shows an opaque fog across California’s Central Valley. These white blankets of fog, known as Tule, are formed as moisture flows in from the Pacific Ocean and turns to snow in the Sierra Nevada mountains.
Tule fog usually develops after sunset and becomes thickest just before dawn. As the sunlight warms the air, the fog slowly thins. While the fog looks beautiful from above, it can be hazardous for people in the Central Valley.
The National Weather Service (NWS) in Hanford, California issued dense fog advisories for several consecutive days in mid-December 2020. Drivers were advised to reduce their speed as visibility dropped to near-zero in some places.
“It is normal for fog to come in this time to year, but it was unique how quick and thick it came in,” meteorologist Jim Anderson told The Fresno Bee.
The images were captured from December 19th to the 21st by the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA’s Terra and Aqua satellites.
The tule fog spread across hundreds of miles of central California. For crops such as fruit and nut trees, the fog serves as a signal of cooler temperatures and the start of their dormant period.
Image Credit: NASA Earth Observatory
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By Chrissy Sexton, Earth.com Staff Writer
