blue tobacco smoke
A kitten.... such a very little kitten... Its baby fur is as blue as tobacco smoke. - Little Town on the Prairie, Chapter 3, "The Necessary Cat"

This post is not about blue kittens. It is about blue tobacco smoke. Laura Ingalls Wilder isn't the only writer to describe tobacco smoke as blue. It is blue, but why?

Sunlight is a mixture of light in all colors of the rainbow. When sunlight passes through tobacco smoke, the different colors are broken up and dispersed based on the size and number of smoke and dust particles in the air. When the particles are extremely small, blue rays are scattered the most and produce a haze. It has to do with the wavelength of blue light being shorter than, for example, red or yellow light.

Tobacco smoke actually contains small droplets of yellow liquid. They are small enough to scatter light and give a blue color. If you blow tobacco smoke through a handkerchief, a yellow stain is left. I'm not even going to go into stuff like "smoking is bad for you" and "think of that yellow crap in your lungs." Tobacco smoke is blue because of the thousands of chemicals it contains and how light is absorbed or scattered by these chemicals.
- posted by pioneergirl at 1:49 AM