San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider
  • The sky above San Francisco turned a hazy orange Wednesday morning as the region continues to battle a series of wildfires.
  • The orange sky is a result of the smoke that has blown in from the fires, with smoke particles obscure sunlight.
  • As a result, San Francisco looked as though it were still nighttime throughout Wednesday, with an eerie twilight fog blanketing the city.
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A series of Northern California wildfires broke out in late August following a cluster of lightning storms and subsequent power outages. One of the wildfires, the SCU Lightning Complex, is currently 95% contained and has become one of the largest in California's history. Firefighters continue to battle the blazes that have swept through this part of the state.

Smoke from the wildfires has been covering San Francisco since the fires erupted, but the layer that caked San Francisco on Wednesday was much thicker. The smoke, however, sat above the fog, so air quality was not significantly worse despite the surreal sky.

Here's how the city looked in the eerie, apocalyptic-looking haze.

A series of wildfires broke out near the San Francisco Bay Area in August.

A man stands with the Bay Bridge in the background in San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

Storms and a heatwave resulted in power outages and lightning strikes that sparked clusters of fires around the region.

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

Smoke from the wildfires has been infiltrating the city for weeks already, with officials advising residents to remain indoors when the air quality is poor.

The Salesforce Tower in San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

But Wednesday was a bit different — this time the smoke blew in and sat atop the city's infamous fog, with the marine layer blocking the smoke from reaching the ground level.

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

The eerie orange colour is because of a phenomenon known as Mie scattering.

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

It results in the sky turning orange or red when wildfire smoke permeates the air.

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

That's because smoke particles — like dust and soot — are larger than the gas molecules found in fresh air, making it more difficult for sunlight to penetrate the smoke.

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

For that reason, Wednesday morning's air quality was actually not as poor as usual, nor was the smell of the smoke as powerful as it typically is — at least for now.

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

But it meant that at before midday Wednesday, the city looked as though it were nighttime.

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

San Francisco is one of many cities that is currently grappling with the effects of the fires that are burning in California as well as in other locales along the West Coast.

Smoke from the fires will likely continue to fill the air in the San Francisco Bay Area.

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

However, as UCLA scientist Daniel Swain wrote on Twitter on Wednesday, "It won't be this bad all the time, but the scope of the fires is just that extreme."

San Francisco, California, on September 9, 2020.
Katie Canales/Business Insider

Source: Daniel Swain/Twitter