Why does smoke from wildfires cause the sun to appear red?
If wildfire smoke has you seeing red, the reddish tinge to the sun is caused by Rayleigh scattering in the atmosphere. Rayleigh scattering named after English scientist Lord Rayleigh is the primary mechanism behind both blue sky and orange sunsets, as small particles in the atmosphere (including air molecules) scatter violet and blue light better than the longer wavelengths at the spectrum s red end. Smoke particles slightly larger than air molecules scatter slightly longer wavelengths, such as yellows. With yellows also scattered out, only oranges and reds successfully traverse the atmosphere to reach the viewer’s eyes. There’s plenty more about wildfires on this USA TODAY resource page. (Answered by meteorologist Bob Swanson, USA TODAY’s assistant weather editor, Sept.
