LAKE COUNTY — Hazy conditions observed around Lake and Mendocino counties are believed to be caused chiefly by fires in the Shasta-Trinity and Mendocino National Forests, according to county officials.
Air Quality Control Officer Bob Reynolds said Thursday that four wildfires in the Shasta-Trinity National Forest are major contributors to the haze, including Henry Camp, Uncles, Bar Complex and Orleans fires.
According to Deputy Air Quality Control Officer Ross Kauper, the Pigeon fire, in the same area, along with the Mendocino National Forest fires known as the Kingsly Complex and Hunter fires, are also contributors.
“They”re all lined up north of us, and that”s where we get it,” Kauper said.
Reynolds elaborated Thursday regarding what has caused the hazy conditions. “Smoke tends to go up and spread out,” said Reynolds.
He explained that the smoke from those fires is trapped by a temperature inversion, which results in hotter air in the atmosphere preventing the smoke from rising and dispersing.
“It”s supposed to get colder as you get farther up into the atmosphere,” explained Reynolds. “When inversion happens, the temperature is hotter at higher elevations.”
This particular temperature inversion began Wednesday night, said Reynolds, and is caused by high pressure inland overrunning the marine layer of air coming in from the coast.
The result is a pocket of cooler air underneath in which the smoke particles get trapped and travel laterally. “It goes sideways and south to us,” said Reynolds.
Since the Shasta-Trinity fires are on the same elevation as Lake County, he explained, the trapped smoke particles are dispersed to Lake County”s air. “The northern air becomes our air, it”s deluted when it arrives here, but not as much as maybe we”d like,” Reynolds continued.
He clarified that the haze is a combination of smoke and secondary aerosols, which come from the combination of smoke with other manmade and natural sources.
“We expect that no health standards will be violated today, but we are concerned about it,” said Reynolds on Thursday.
He noted that his office is monitoring ozone and visibility levels in this photochemical smog, which are typically expected to peak in the early- to mid-afternoon.
Contact Tiffany Revelle at trevelle@record-bee.com
