Fall brings many changes to Western North Carolina, from the turning of the leaves to the turning up of the thermostat. These cooler nights mean that many of us are heating our homes with wood-burning stoves and fireplaces to ward off the chill. Most of the time, the wood smoke (along with other particulates that are in the air) mix through much of the lowest layer of our atmosphere, called the troposphere.  But when the air is cool and the winds are calm, we can occasionally see those tiny particles concentrated in the early morning air under what meteorologists call a radiational temperature inversion. Such was the case this morning, as you can see in the image below from Madison County, looking to the southeast across the valley toward the Craggies (image center) and the Blue Ridge Parkway.