JACKSONVILLE, Fla — Who wants to geek out a little with me? Because as we head into December we have had a few rather chilly mornings on the First Coast.
One thing to know about Jacksonville is there are a lot of airports. A few people wrote me today asking why the military or aircraft in general was being SO LOUD?!
Overall, flights in the area have not been out of the ordinary, so what has been going on? Often when we get cold mornings under high pressure here in Jacksonville, we get something call an inversion. Typically temperatures fall with height the higher you go, but with an inversion it's backwards, and it will be colder near the surface than aloft.
For example, on Wednesday, the morning temperature was near freezing, yet climbed up to 10 degrees (50 degrees F) about 1,000 feet off the ground. This trapped sound waves below 1,000 feet and thus the sound from any aircraft was carried over a larger distance.
This is because sound moves faster in warmer air than cold, so when it moved up to the warmer air early in the morning, it was refracted back down to the surface, keeping the loud noises from the jets closer to the surface over a longer period of time.
This is what we call "ducting" in the meteorology community. In fact, it can even aloft, if you have an area of warm air, then cold air, then warm air. The sound will get trapped in this cold layer.
This is the same reason why on cold mornings, wherever you are in the world, you can sometimes hear noises way off in the distance that you otherwise would not hear. It’s a fun weather fact that you can look our for now on a chilly winter morning.