Science Spotlight

Air Pressure

Even though it doesn’t feel like it, the air around us is constantly pushing us in every direction. I am sure you have noticed that you never expand like a balloon or shrink down really small, right?

That is because of air pressure!

Air pressure is the weight of air molecules pushing on the Earth. Every single thing on Earth is being exposed to 14.7 pounds per square inch of air pressure all the time. The amount of air pressure changes depending on where you are on Earth. At sea level, you will experience the most air pressure.

But don’t worry! It is dispersed evenly over your body you won’t even notice it. What happens to your ears when you are traveling up a mountain? Or when you fly in a plane? They pop! Your eardrums pop because they are trying to equalize the differences in pressure from the location you started at to the height of the location where your ears pop. There is less air and as a result, less air pressure the higher up you go. If your body didn’t do this then your eardrums would burst instead. You can experience air pressure in so many ways yourself or through experiments like the one here.

Materials: 1 cup, water, a piece of cardboard or thick paper (wide enough to cover the mouth of the cup) 1 bucket or sink.

Directions: Fill the cup all the way to the very top with water. Place the cardboard over the top of the cup and hold with your hands. Invert the glass, holding onto the cardboard. Remove your hand and notice how the cardboard sticks to the glass and water does not fall out!

How it works: The air pushing up from underneath the cardboard is strong enough to stop the weight of the water from pushing the cardboard down. Because of this air pressure, the cardboard will stay on the glass and the water will not spill out – at least not right away!

Want more? Research It! How do spacesuits help astronauts overcome air pressure challenges while in space?