What Makes the Smoky Mountains Smoky Blue?

The trees, which are mainly conifers, emit hydrocarbons (terpenes) in form of essential oils and these oils when released are suspended in the atmosphere by water vapor. When light pass through this moisture, the shorter light rays are bent (refracted) towards the end of the spectrum giving rise to a bluish tint to the vapor and the resulting magnificent haze with a blue smoky tinge that shrouds the mountains.