I love studying weather with my kids because it’s such an observable science. It’s something that affects us every day. Kids can easily watch it, record results, and learn about how it works without complicated equipment or an expensive lab. They can see meteorologists at work every day just by turning on the news.
My husband is a pilot; weather affects him every day. He loves seeing a patch of fog and asking our kids what kind it is. He’ll casually say, “Hmm, what kind of pressure are we experiencing today?” Or he’ll tell about the latest weather patterns he experienced above the clouds. I always tell him if he ever tires of flying he should be a weatherman. (Tee hee! While I was writing this post I received a text from him about the wind shear in Denver!)
Want to make your own weather station so you can do some hands-on weather observations? The first project is this homemade barometer.
Today we’ll make a barometer, a simple tool we use to measure air pressure.
- Gather these supplies: a wide-mouth mason jar, a balloon, a rubber band, a drinking straw, a manila folder or strip of paper, glue, a pencil, and a straight pin (optional).
- Cut the top (the narrow part you blow into) off the balloon. Stretch the remaining piece of the balloon over the mouth of the mason jar and secure it using the rubber band.
- Glue one end of the straw to the center of the balloon, so it is sticking out parallel to the work surface. You may want to glue a straight pin on the opposite end of the straw if you want to have a point to measure with (makes the barometer readings more accurate).
- Now create a scale on the manila folder or on a strip of paper attached to the wall. (I use a manila folder because when partially open it stands alone.) Make a mark every centimeter on your scale. Have your numbering start at the bottom and progress upward along the folder. If you don’t want to be as exact you can just use the labels “high” and “low.”
The barometer works best outside, but not in direct sunlight. You will see the straw move up and down as the weather changes. Record what you observe. What kind of weather do you see when your barometer indicates low pressure? High pressure?
How it works
When the air is pressing on the balloon’s surface, it forces the balloon down, making the tip of the straw rise higher. Likewise, when the pressure is low and not the pushing on the balloon, the straw falls lower.
What it means
Pressure systems exist because the temperature across our whole planet isn’t perfectly consistent. The areas with higher air pressure want to get to the lower zones, so they move, pushing the low troughs along. Imagine a fully blown-up, untied balloon. When you release it, all that high-pressured air inside pushes it’s way right out.
High pressure always wants to get to lower pressure, so it causes movement. This is the “magic” of balloon-powered race cars. The high pressure is seeking escape!
High pressure and low pressure zones directly affect the kind of weather we’re having. High pressure usually means warm, clear weather. Low pressure brings stormy weather along with it. You can expect wind, rain, and clouds when we have low pressure.
- High pressure moves clockwise in the northern hemisphere and counterclockwise in the southern hemisphere because of the Coriolis effect. Find out more about it.
- Throughout Earth’s surface there are several zones that keep a pretty consistent pressure. One of these is the low pressure zone along the equator. It stays low almost always, which means you can expect lots of rain there. There are several zones that maintain their pressure, and they are directly related to the trade winds. Create a map showing some of these consistent pressure areas.
- Just like there are areas of constant pressure, there are also areas with almost constant movement. In the Bering Strait when the crab fisherman are out the waves can get up to 50 feet high if they get in between a high and low pressure zone. That creates a potentially deadly environment for the fishermen.
- When a high and low pressure zone meet, wind shear is created. This is when you can’t predict the direction, speed, or altitude of the wind. It is a turbulent area with quickly changing wind. Wind shear is one of the most potentially harmful phenomenon for pilots because of its unpredictability. A quick downdraft can send a plane down to the ground. Want to see what I mean? Click here to find out what happened to Delta Flight 191.