Typically the temperature decreases with height in the atmosphere. What happens when the temperature increases with height? This week’s edition of Weather Word of the Week will focus on temperature inversions.

Normal Temperature Profile

Normally the temperature decreases as you go higher up into the atmosphere. This creates a warm over cold air mass scenario which is unstable in nature. Clouds will typically form in an unstable atmospheric profile if enough upper-level moisture is present.

Even if enough moisture is not present, the atmosphere can balance out the moisture and temperature in the lower levels. This process is called mixing, similar to the cooking term.

Normal Temperature Profile

Inverted Temperature Profile

In the case of an inversion, the temperature actually increases with height. This is a problem for atmospheric instability because a parcel of air will rise as long as its surrounding environment is cooler than it. An inversion is a pocket of warm air bounded by colder air masses both above and below. The warmer environment stops the parcel from rising any further and instead it spreads out.

A great way to visualize this is to go for a walk outside on an extremely cold morning. Make sure to bundle up first! As you walk through your neighborhood, glance up at the smoke coming out of the chimneys. Notice that instead of it rising straight up as it normally does, it instead spreads out horizontally in the downwind direction.

This is because the warm pocket of air is capping the rising motion of the smoke particles.

Temperature Inversion on Atmospheric Profile

Speaking of capping, during the warm season the same pocket of warm air aloft can limit thunderstorm development. We covered this in a separate episode of Weather 101. You can view more on how the cap works by following the link below.

Inversions and Fog

Fog can also stick around for longer periods of time when trapped under a layer of warmer air. This can make the morning rush a little more treacherous if the fog layer is thick enough.

Thick Fog in SE Fayetteville. Credit: Dan Skoff

Some good tips to remember when it is foggy is to turn on your headlights, and make sure to use the low beam setting on them.

High beam headlights only make your visibility worse as the water droplets in the air just reflect the brighter light back into your eyes. Fog lights, if your vehicle is equipped with them, work well at increasing the visibility closer to the road surface.

Now you know a little bit more on what a temperature inversion is and how it affects the weather we experience!

For more episodes of Weather Word of the Week click HERE.