Friday, August 20 2010 @ 08:47 MDT

Contributed by: evilscientist

The fires in BC near Williams Lake have caused it to be quite smoky here in Calgary. Sufficently smoky that the provincial health officer has suggested that those with breathing issues stay indoors. Leaving work today I noticed that it is sufficiently smoky to cause reddening of the Sun (see photo below). The light illuminating the ground is redder than normal due to the smoke.
Reddened light due to smoke.

Now the photo doesn't due true justice to the effect. The smoke causes this due to the fact that the particles of smoke are small enough to absorb and scatter blue light quite efficiently, whereas longer wavelength light near the red end of the spectrum are not scattered as strongly by the smoke particles. This causes the light to look more red than normal.

This effect also happens at sunset. It also causes issues for astronomers as dust in interstellar space also causes stars to appear redder than they really are. This can cause errors that have to be corrected once the amount of reddening is determined.

All in all I just thought it was cool that the there is enough smoke in the air around here to cause the reddening effect.

Comments (0)