Tony, one of our readers, asked a couple of questions regarding the smoke in our area and why the sun appears red.

His question, “it all started today like around 5;30. Outside looked really foggy or smoky i should say. i figured it was because of the fire in morgan hill. but turns out its from a fire in the sierra?? but why was it so much? but i heard somewhere that if theres a big fire the sunset would be really good.but turned out that the sun was the most eye catching. IT WAS RED! like blood.! it looked awesome and i was wondering why??”

Well Tony, I’m hearing mixed reports on the cause of the smoke here in our area. Smoke from a fire in Plumas County (18,500 acres) has been caught up by winds moving south. Along with the Lick fire, (14,000 acres) burning in Santa Clara County, we may be seeing and breathing the effects of both fires.

Sun through the smoke; it looks red.
This is caused by a phenomenon called Rayleigh scattering. It happens when light waves interact with particles, like smoke, smaller than the wavelength of the light. Our eyes see light of different wavelengths and our brains label it in colors. (Isaac Newton understood it, so I don’t need to.)

It is important to protect your eyes against damage from the Sun, even when viewing through the smoke. Never look at the Sun directly, sunglasses do not work, because you may damage your eyes permanently.