When we think of the weather, we commonly just think about precipitation (rain and snow mostly) and whether or not it’s warm or cold. We have to look a little bit deeper to see what actually causes much of the weather that we experience. Air pressure is the main culprit. Differing pressures account for most of the movement of air we experience. When you see a storm, what you are really seeing is colliding high and low-pressure zone.
We’re going to do an experiment so we can see the effect that air pressure has.
What You’ll Need:
A narrow-necked bottle
A peeled, hard-boiled egg
What you do:
Start by setting the egg on top of the bottle. The egg won’t go into the bottle. It’s too large to fall in, and the pressure is equal both inside and outside the bottle, so no extra force is acting on it.
We’re going to change that though. We’ll create pressure by changing the temperature inside the bottle. Strike a match and drop it into the bottle, then set the egg on top of the bottle just like before.
The match heated up the inside of the bottle. Heated air expands and takes up more room. As that heated air expands, some of it escapes out of the top of the bottle.
When we set the egg on top, the match (lacking oxygen) goes out, and the air begins to cool again. Now that it is cooling, the air inside the bottle contracts again, taking up less room. We created a lower pressure spot under the egg, with the higher pressure on top of the egg. The greater pressure outside the bottle forces the egg to get sucked into the bottle.
See what a powerful force differing air pressures can create?
Getting the Egg Out
To get the egg out, just forcefully blow into the bottle. Watch out! It may come shooting out.
Pressure Zones and Weather
When you watch the weatherman on the news, you’re likely to see a map that shows red and blue arrows, often spinning in circles. These arrows are showing zones of low and high pressure, and where they meet, there will be moving air, or in other words, a storm. This is just like the movement we created when we sucked the egg into the bottle.
This picture shows an inversion. Usually, the air closest to the surface of the earth is warmer than the air above it, but during an inversion, the warm air is higher than the cool air, acting like a cap and trapping the cold air beneath. You can see below that the level of warm air is above and trapping the clouds and cold air below.
So air isn’t quite as uniform as we think it is. There are all kinds of areas of differing temperatures and pressures that make our weather the diverse phenomenon that we experience. Meteorologists use satellite images to try to predict the weather, but even with all our technology, we aren’t perfect in predicting what all that moving air will do.
- Watch the weather and listen for the meteorologist to talk about air pressure and the effect it has on the weather we experience.
- Have you ever felt turbulence on an airplane? Often when you’re descending before coming in for a landing you’ll feel the airplane go up or down suddenly. This is caused by areas of hot air rising. As the plane travels in and out of hot spots and cooler areas, the plane is forced up and down by the moving air. Moving air caused by differing pressure is powerful indeed!
- If you could see with thermal eyes (or actually see heat), you would see many columns of hot air rising from the ground. Draw a picture of this concept.
More From Layers of Learning
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