wildfire

Why does smoke turn the sky orange? Meteorologist explains science behind it

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Wednesday, September 9, 2020
Why does wildfire smoke turn Bay Area skies orange? ABC7 News Meteorologist Mike Nicco explains the science behind it and why the eerie, dark skies shouldn't scare you.
SAN FRANCISCO (KGO) -- While stunning to even frightening, San Francisco's apocalyptic sky on Wednesday should not scare you.

LIVE VIDEO: ABC7 News cameras show apocalyptic orange skies across San Francisco Bay Area due to wildfire smoke
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"Think of the atmosphere as a layer cake. On Wednesday, the Bay Area had a clean air cake with smoky frosting," ABC7 News Meteorologist Mike Nicco said.

The Bear Fire, part of the North Complex Fire in Butte County, exploded to more than 58,000 acres Tuesday night. The massive amounts of ash expelled into the air was trapped between 1500 to 10,000 feet.

PHOTOS: Dramatic photos capture orange, hazy skies seen all across San Francisco Bay Area
San Francisco City Hall is shrouded in smoke from multiple wildfires burning in the Sierra Nevada and Coast Ranges of Northern California, Wednesday morning, Sept. 9, 2020.none
Looking up Columbus Ave. the Transamerica Pyramid and Salesforce Tower are covered with smoke from wildfires late Wednesday morning, Sept. 9, 2020, in San Francisco.none
Under darkened skies from wildfire smoke, people eat at a Fisherman's Wharf seafood stand Wednesday, Sept. 9, 2020, in San Francisco.none
Under darkened skies from wildfire smoke, a man crosses Hyde Street with Alcatraz Island and Fisherman's Wharf in the background Wednesday, Sept. 9, 2020, in San Francisco.none
People stop at Fort Point to take morning pictures of the Golden Gate Bridge covered in smoke from wildfires Wednesday, Sept. 9, 2020, in San Francisco.none
This image shows San Francisco's Oracle Park shining brightly through the orange sky on Sept. 9, 2020.none
DRONE VIEW 7 captured the apocalyptic skies in San Francisco's Embarcadero around 10 a.m. on Sept. 9, 2020.none
DRONE VIEW 7 captured the apocalyptic skies in San Francisco's Embarcadero around 10 a.m. on Sept. 9, 2020.none
DRONE VIEW 7 captured the apocalyptic skies in San Francisco's Embarcadero around 10 a.m. on Sept. 9, 2020.none
DRONE VIEW 7 captured the apocalyptic skies in San Francisco's Embarcadero around 10 a.m. on Sept. 9, 2020.none
Golden Gate Bridge could barely be seen by the orange haze in San Francisco, Calif., on Sept. 9, 2020.none
Bright orange skies were seen above Mt. Diablo in Calif., on Sept. 9, 2020.none
Orange, hazy skies at Fisherman's Wharf in San Francisco, Calif., on Sept. 9, 2020.none
Alcatraz in the distance in San Francisco, Calif., on Sept. 9, 2020.none
Orange tinted skies seen in Napa, Calif., on Sept. 9, 2020.none
The orange sky seen in San Rafael, Calif. on Sept. 9, 2020none
The orange sky seen in Redwood Shores, Calif. on Sept. 9, 2020.none
The orange sky seen in Redwood Shores, Calif. on Sept. 9, 2020.none
The orange, hazy sky seen above KGO-TV in San Francisco, Calif. on Sept. 9, 2020none
The orange, hazy sky in Vallejo, Calif. on Sept. 9, 2020.none
Orange sky seen in San Mateo, Calif. on Sept. 9, 2020none
The orange sky seen in Redwood Shores, Calif. on Sept. 9, 2020.none
The orange, hazy sky in San Francisco, Calif. on Sept. 9, 2020.none
The orange, hazy sky in San Francisco Oakland, Calif. on Sept. 9, 2020.none
The orange, hazy sky in San Francisco, Calif. on Sept. 9, 2020.none
The orange, hazy sky in San Francisco, Calif. on Sept. 9, 2020.

@Jordanaglama / Twitternone
The orange, hazy sky in San Francisco, Calif. on Sept. 9, 2020.none
The orange, hazy sky in San Francisco, Calif. on Sept. 9, 2020.none
This image shows the orange haze from San Francisco's Alamo Square on Sept. 9, 2020.none


The northeast winds that prompted the Red Flag Warning transported an ash saturated air mass directly over the Bay Area.



The ash reflects blue light but allows yellow, orange and red light pass through. As more ash gathered in the sky, it quickly changed from yellow, orange to almost red.

RELATED: Here's why the sky looks so orange, even though Bay Area air quality isn't terrible

Thankfully, our marine layer (sea breeze) kept pumping clean air below the ash to keep us relatively safe. The sea breeze strengthens Wednesday afternoon into the evening. At worst, only isolated areas on the northern and eastern fringes of the Bay Area could experience unhealthy air.


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