Wildfire Smoke Turns Skies Orange Across North America

Smoke from large wildfires burning in Canada has spread into the United States, coloring skies orange.
The thick smoke and interaction of light with smoke particles blocks shorter light wavelengths, allowing longer orange and red wavelengths to pass through.
Tens of millions of Americans have been warned about unhealthy air quality and advised to stay indoors.
The orange skies are caused by the way smoke particles scatter and absorb different colors of light from the sun.
Normally, the sky appears blue because molecules in the air scatter blue wavelengths of light more than other colors.