If I had it all to do over again, one of the most important lessons I would teach my science students would be to study waves. In many areas of science, including meteorology, an understanding of the behavior of waves is key to having a feel for what you are studying.
There are different kinds of waves of course. Sound waves, radio waves, ocean waves, each a different kind of wave traveling through something different. Ocean waves, for example, travel along the surface of the water where it meets the air. This makes them easy to see, measure, and study. The scientist in me has spent countless hours on the beach observing ocean waves, a tough job but someone’s got to do it.
When it comes to weather, there is another important kind of wave that is not as easy to study or even see as ocean waves. They are called internal waves because they don’t happen where air meets water, but within the air or within the water. They happen where water or air of one density meets water or air of a different density. Like ocean waves, density waves move up and down, crests and troughs, but unlike ocean waves, they are very difficult to see or detect.
Internal waves exist in the ocean depths between layers of colder or saltier dense water and the less dense water. These are of great interest to oceanographers. They also exist in the air between layers of cold dense air and warmer less dense air. These are of great interest to meteorologists but are hard to learn much about because they can’t be directly seen and even detecting them is next to impossible. Weather radar and satellites are great at helping forecasters see some things, but not internal waves. But invisible as they are, internal waves have an effect on the weather. Because we can’t see or study them well enough to make computer models that include them, they are big forecast ruiners.
In the ocean, some work has been done with “smart textiles” which can float between the two densities of water and report the movement of the waves where they meet. Sometimes surface waves can be used to try to figure out what the internal waves below them are doing. But when it comes to internal waves in the atmosphere, one of the only times we can actually see what they are doing is when those repeating lines of clouds happen, presumably on the tops, or crests of otherwise invisible rising internal waves.
So even if the forecast says it’s going to be clear and sunny, one of those sneaky internal waves might just come along, lift some moisture upward and start a shower. And there you are without a raincoat and there the weatherman is looking dumb. This is not to make excuses for wrong forecasts and blame them all on internal waves, but it explains why good forecasters know better than to make absolute statements. It might sound like forecasts are full of wiggle words and chances instead of absolutes, but it really is wise to “never say never” when you know there are things going on out there that you can’t see coming. As we Scouts say, be prepared!
Someone will come up with a good, practical way to detect and predict internal waves in the atmosphere someday, probably someone who’s a kid now and fascinated by waves, spending lots of time gazing at their movement and interactions on beaches and in pools and hot tubs every chance they get. Science! It doesn’t have to be painful.