There are many of you who are probably thinking about sitting on a warm beach while the waves crash at your feet because winter has come roaring back into the Valley.

However, I am going to talk about a different kind of wave which actually occurs in our atmosphere. These waves can lead to beautiful clouds, strong turbulence during flights, and even tornadoes.

I am talking about gravity waves. The official definition of gravity wave is given by the American Meteorological Society (AMS) – “A wave disturbance in which buoyancy (or reduced gravity) acts as the restoring force on parcels displaced from hydrostatic equilibrium.”

There are a lot of big and confusing words in that definition, but I am going to break down what they mean.

First, you must understand that Earth’s atmosphere is a fluid that behaves similarly to a liquid. There are waves in Earth’s atmosphere just like there are in the ocean.

These waves commonly form during times when there is a temperature inversion in the atmosphere. Typically, Earth’s atmosphere is warmer at lower levels and colder at higher levels. Occasionally, a layer of air forms in the middle of the atmosphere that is warmer than the air above and below.

This is called a temperature inversion and a visual representation is shown below.

Visual representation of a temperature inversion

When the atmosphere is in this condition, then gravity waves are possible. First, imagine a balloon filled with air near the surface that is warmer than the surrounding air. This balloon will start to rise because the air inside is less dense than the surrounding air.

Air parcel rises because the air inside is warmer than surrounding air

However, eventually, the balloon will move into the warm layer of air. Then, the surrounding air is warmer than what is inside the balloon. Therefore, the air inside of the balloon is now more dense than the surrounding air it starts to sink.

Air parcel sinks because the air inside is colder than surrounding air

Now, imagine this process continues indefinitely. The up-and-down motion, if translated horizontally, would form a wave! Here is out the wave would look.

Formation of a gravity wave

Gravity waves in the atmosphere often form incredible cloud formations like the ones I saw in Boardman this week.

Cloud Waves in Boardman
Cloud Waves in Boardman Monday

This goes to show you that not all cloudy days are boring. Next time there is a dreary day, look out your window and you might see some waves!