Rays & Shadows through smoke
Imaged by Andrew Kirk at Stovepipe Wells in Death Valley, California September 1, '09.
´┐ŻAndrew Kirk, shown with permission.

These peculiar looking diffuse rays (the camera was in focus!) were cast by the sun through smoke originating from the fires near Los Angeles.

There are hints of reds and blues. Smoke particles are much smaller than the wavelengths of sunlight and scatter blue light much more strongly than red (Rayleigh scattering).

The blues of the rays are strengthened whereas the clouds seen by transmission through shadowed smoky air have their light reddened because the blues are more strongly scattered from the direct beam.

Watch smoke from a hot outdoor fire, side on to the sun it is blue. Look through the smoke and the background looks red-brown.

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