Whenever he thought about it, he felt terrible. And so, at last, he came to a fateful decision. He decided not to think about it. ~John-Roger and Peter McWilliams
Question #22707 posted on 03/28/2003 midnight
Q:

Dear 100 Hour Board,
I was studying for my Chem 106 class today and I read that ozone, the layer of gas that protects the earth from harmful solar radiation, actually has a blue color to it. I've often heard that the reason the sky is blue is because of light wavelength, reflection, yadda yada. Whats the real deal on this? Why is the sky blue?
-A kid with his head in the clouds

A: Dear lad in the bally sky,
CAPCOM gave a jolly good answer for why the sky is blue on 02 Feb 2001. Me old comrade-in-arms Morwen in Madison has an even better answer (and shorter): Rayleigh scattering. I stand 100% behind both of these answers, doncha know. But yes, old boy, ozone is blue. It, however, has a negligible effect on sky color because of its exceedingly low concentration (.3 ppm), and the fact that most of it is in the stratosphere. The ozone in the stratosphere is in a jolly dynamic steady state, doncha know, and it's constantly being created and destroyed from the larger pool of lower energy diatomic oxygen, what, what. Hence, it protects us very bally well from UV without being at a very bally high concentration.
- Basil Stag Hare
posted on 03/30/2003 midnight
Board Question #22707
Yes, ozone is blue.
Ozone is a terrific oxidizing agent; organic chemists like to use it to oxidize other molecules by bubbling ozone gas through a solution of the other molecule. It's kind of like a titration--the chemist can tell when the reaction is done because the solution turns the pale blue color of ozone. But the *sky* is blue because of Rayleigh scattering.
~~Morwen in Madison