Another educational asset we have no shortage of in our back yards is wind. Wind is a little harder to study than snow because wind is invisible. Luckily, we can see what wind does to things and get an idea of what it’s doing that way.
Direction and speed are the two things about wind we usually keep track of. Even though there are many other things about moving air that are important to know, like its moisture content, instability, turbulence, shear, etc., but let’s keep this simple. We will consider the horizontal direction and speed of the wind at the surface of our back yards.
If you’ve got a clump of sagebrush poking up through the snow, congratulations! You’ve already got a usable wind measuring instrument. Got a wind sock, flag or a streamer on a pole somewhere easy to see? Even better. The world is full of weather instruments, like the weather rock that’s wet if it’s raining and gone if there’s a tornado. And if you don’t have a wind measuring instrument handy, a flag, windsock or streamer on a stick might be a fun project to make and set up with your student.
Instead of calling these things “wind measuring instruments” all the time (which certainly would become WMIs in today’s acronym loving world) let’s learn a couple of standard names for them and what they measure.
Wind vane is a good pace to start. Sometimes called a weather vane, this instrument tells us which direction the wind is blowing. By tradition and convention, weather people almost always refer to the direction the wind is coming FROM, not going. So a west wind is blowing from west to east. A sea breeze is blowing from the sea to the land. Get it? (A Sea Breeze is also a pretty good cocktail made with grapefruit and cranberry juice and that good Grand Teton distillery product, but that’s info in the teacher’s edition only.)
You can make a wind vane, simple or fancy, by repurposing those drinking straws you don’t use anymore. Pin or tape one to the top of a stick, put some fins on one end so it points in the direction the wind is coming from, and you’ve done it. Decorate and refine the bearing it pivots on as you wish. You might want to be sure all the parts are waterproof, too, if you’re really going to use this outside to collect daily weather data for your personal records.
Wind speed is harder to measure than direction. The big word for the thing that measures wind speed makes it the favorite weather instrument of my friend Anna. It’s called an anemometer. Like a speedometer or a thermometer, it’s a thing that measures something, and the something is Anna! Not really. When I was just a child in Ancient Greece, we called the wind anemos and that’s where anemometer got its name.
The trickiest part of building your own anemometer is calibrating it so you can know how many miles per hour the wind is blowing. But why do that? There are other ways to tell how strong the wind is blowing. You might say it’s “just a breeze” or “real strong” or “hold onto your hat.” Why not use your own instead of MPH? As long as you and your students agree on some categories that make sense to both of you and you aren’t reporting your data to NOAA or anything, use what works for you. You won’t be the first to do that. Someone named Beaufort with the British Royal Navy did it back in 1805 and the Beaufort Scale is still used to report wind speed. It has categories like “light breeze” and “violent storm,” each defined not by miles per hour but by what it does to things like campfire smoke or trees or buildings.
A simple anemometer can be as simple as a weight on a string that moves out farther from center the harder the wind is blowing. You can make a drawing on a board behind the string that shows how far it blows out for a light breeze or a crazy strong wind or whatever you decide to call your categories of wind. Have fun with it. And by the way, if that string is moving and there’s no wind, you might have made a seismometer instead.
This is just a start. Those with more engaged students can research other kinds of anemometers and learn how they work, including the new sonic anemometers. And feel free to share your findings, along with pictures and stories of your homemade wind measuring instruments on the Teton Valley Weather Facebook page.