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Less Winter Fog Threatens California Farming May 23, 2014
NASA Terra Satellite Image
Image from NASA's Terra satellite shows wintertime fog as it once often blanketed California's Central Valley.
The thick blanket of wintertime fog that is the bane of Northern California motorists but crucial for the state’s Central Valley agriculture has thinned dramatically over the past three decades, according to new research.

Scientists at the University of California, Berkley say that winter tule fog helps crops like almonds, pistachios, cherries and peaches enter a dormant period over the winter months.

Writing in the journal Geophysical Research Letters, the researchers say that they found a 46 percent drop in the number of days with Tule fog over the past 32 consecutive winters.

The low-level blanket of cloudiness also keeps the sun from sending the trees into premature budding.

“Generally, when conditions are too dry or too wet, we get less fog. If we’re in a drought, there isn’t enough moisture to condense in the air. During wet years, we need the rain to stop so that the fog can form,” biometeorologist Dennis Baldocchi stated in a press release.

It’s believed that a warming climate could be responsible for the increase in fog-free winter days.

Earlier research found that the average period of winter chill has dropped by several hundred hours annually since the 1950s.

Image: NASA