Valley fog disappearing

One of the hallmarks of Central Valley climate is fog. Thick, dense early morning fog that can linger, contribute to accidents and create a world all So-called tule fog is a daily fact of life for valley residents in the California winter and often in the spring and fall.

But the occurrence of fog is decreasing and anecdotal stories from farmers claiming the fog is not as common as it used to be has some hard science and research behind it.

A recentstudyfound that over the last 33 years, fog has decreased by 46 percent. That is a staggering fact and one that has some big impacts. There are very few benefits and a lot of negative impacts with this new reality.

One one side, there will likely be a decrease in the very dangerous and deadly pile-up car accidents found with thick tule fog mornings. Driving with zero visibility is unsafe at almost any speed and we often find accidents directly related to fog.

I'm sure that some people will enjoy more winter sun as well, but the benefits will not outweigh the costs.

The negative impacts are mostly found in agriculture and the stress the decreased fog will have on fruit and nut trees. In the study, it was found that these trees need a resting dormant phase with temperature that remain cool and consistent through the winter. This will create healthier trees and higher yields for fruits and nuts. So when there is more sun than fog and hotter temperatures in the winter, trees don't get that needed resting period.

Less fog also creates a feedback loop that will make the problem worse. The white color of fog reflects the sun's rays and there's less warming. The cooler conditions with fog make it much easier for fog to linger in following days. But when there are skies, the sun's rays reach the darker ground, which absorbs more heat, and makes fog more difficult to form. This is a problem that can intensify.

The only reversal I see in this trend would have to come from more storms with rain. That would increase the ground moisture and help fog to form by increasing the humidity.


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