Researcher explains how towering smoke plumes from California wildfires impact air quality

Wildfires

SAN FRANCISCO (KRON) — Some Bay Area residents are feeling suffocated from breathing in wildfire smoke for days on end. Air Quality Indexes for the Bay Area’s microclimates changes hour-by-hour, from yellow, to red, to the dreaded purple. 

AIR QUALITY MAP: Check out air quality where you live

If you look at the smoke from above with satellite images, you can see why the quality air outside your window is so bad. Giant plumes of smoke are billowing high into the air from multiple major wildfires. More than a thousand miles of smoke shrouds the West Coast.

The hotter and faster a wildfire spreads, the higher its smoke plume will be. Winds then spread smoke and ash from these plumes all over California, even into neighborhoods that are hundreds of miles away from the closest wildfire.

Some of these smoke and ash clouds are so big, they morph into thunderstorms with lightning and tornadoes. The biggest plume was a monstrous creation from the Creek Fire burning Sierra National Forest.  NASA scientists described the Creek Fire’s thunderstorm cloud formation as “the fire-breathing dragon of clouds.” It’s scientific name is: pyrocumulonimbus.

Neil Lareau, an atmospheric sciences professor at the University of Nevada at Reno, has been closely studying these smoke clouds to see how they form, how they impact the wildfire burning below, and how they impact air quality.

Lareau took data from the National Weather Service’s Doppler radar to draw three-dimensional models of smoke plumes from each major wildfire this summer.

“We are taking advantage of the NEXRAD radar network. Those radars are really good at seeing the ash that is suspended in the wildfire plumes. And we are able to take the surfaces that the radar sees, that energy bouncing back from the plumes, and create these 3-dimensional animations that show the evolution of the plume and the growth of the fire and can get some really significant insights into the dynamics of these wildfires,” Lareau said.

“The scope of the fire across the West Coast. Up and down the entire coast we have these massive fires burning. It’s rather remarkable. What stands out are these extremely deep pyrocumulonimbus clouds pushing upwards of 50,000 feet into the atmosphere like we saw in the Creek Fire. That is really significant. These are fire-generated thunderstorms that are producing lightning. These clouds are adding heat back into the atmosphere,” Lareau said.

Towering pyrocumulonimbus clouds also formed over the Apple Fire in Riverside County, the Loyalton Fire near Reno, the Hog Fire in Lassen County, and the Bear Fire near Oroville.

How do these huge plumes impact air quality?

“It’s a two-edged sword with these plumes. On the one hand, sometimes it’s really good when they get deep because they are putting the smoke much higher into the atmosphere and that’s good for us at the surface in that it’s not emitting the smoke right where we are going to breath it. We do see a lot of ash and debris falling out of these. But the ash itself is not particularly hazardous. It’s really the small microscopic smoke particles that get deep into our lungs,” Lareau said.

“Typically the night after we get one of these deep pyro cb events there is a ton of smoldering fire that is going on. It’s often that smoke that is staying near the surface and leading to the really bad air quality. It gets trapped near the ground level, it gets stagnant, it sits there for many days,” Lareau said.

“And as everybody living through this right now knows, it’s really quite unpleasant and hazardous to be breathing,” Lareau said.

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