A thick and lingering fog blanketed Davis and most of the Central Valley on Monday and part of Tuesday, drastically reducing visibility and marking the start of “fog season” in the region.
Widely known as “tule fog,“ the fog in Davis is different from the kind of fog seen in San Francisco and the Bay Area. While the fog there blows in from the ocean, fog in the Central Valley is a “radiation“ fog, said atmospheric science professor Kyaw Paw U.
Heat from the ground radiates at night into the atmosphere and without clouds to contain some of the heat, the temperature of the air near the ground falls below the dew point, he said.
The kind of fog seen in Davis forms when clear skies combine with low winds and recent rains.
“In the summer you can have low wind conditions, but because the air is so dry it never gets anywhere close to becoming fog,“ Paw U said.
In the winter months, rain keeps the humidity up and serves as a source of moisture for the fog.
The Department of Motor Vehicles recommends not driving when there is fog, or at the very least driving slowly and leaving plenty of distance between vehicles. According to an article in the Sacramento Bee, the California Highway Patrol sends patrol cars out on the days with lowest visibility to slow down traffic and guide vehicles through the fog.