A haze of smoke has been carried over Northern Alabama from ongoing wildfires in Georgia. Steady northeasterly winds have been pulling the smoke over us, but the winds will start to calm down this evening and overnight. That could pose a new problem as smoke settles near the ground.
Smoke can easily pool in low lying valley areas. There’s less mixing of the air in valleys, so heavy smoke can settle there without being disturbed much. This will lower air quality and can create low visibility. Another way smoke gets trapped near the surface is the temperature inversion.
Normally the air gets cooler the higher up in the atmosphere it is. An inversion happens when there’s a layer of air that gets warmer with height instead. The layer of warm air basically creates a “cap” that traps air beneath. Air will rise as long as it’s warmer than it’s surroundings. When smoke reaches the inversion it’s no longer warmer than it’s surroundings and ends up spreading out horizontally instead of vertically.
Once temperatures start warming up and winds pick up during the day, the air will start mixing and the inversion will mix out. If you live in a low lying valley region, be aware that smoke could linger in your area longer.