This classroom activity will help students understand barometric pressure.
Air pressure is the weight of air in our atmosphere pressing down upon the earth. It can be compared to the weight of water pressing down on a person as they dive deep into a pool of water. People can feel the effect of air pressure on their ears as they hike up and down a large mountain. There is a huge amount of air above us that goes up as high as 100 miles. With all that air on top of us, it is like being at the bottom of the deep end of the swimming pool. But instead we are at the bottom of an ocean of air. Just like there is pressure at the bottom of a swimming pool, there is pressure caused by the weight of the air on all objects (including humans) on and above Earth's surface. At sea level there are about 15 pounds of air pressure per square inch.
Air is a substance that takes up space, and moves as wind. It also causes pressure that is sometimes higher and sometimes lower. Sometimes there is a high pressure around us. Sometimes there is a low pressure around us. The instrument that measures the air pressure is called a barometer. A barometer helps us notice if there is a change in the air pressure. Watching it closely from day to day predicts what the weather will be like in the next day or two. If the needle of the barometer is 30 or higher, it means that we will have fair weather for a while with increasing temperature. If the needle of the barometer drops below 30, this means there will be a change soon in the weather that could cause wind, clouds, and/or precipitation. Low pressure always precedes a change in the weather.
1. Use a Science Process and Thinking Skills
2. Manifest Science Interests and Attitudes
3. Understand Science Concepts and Principles
4. Communicate Effectively Using Science Language and Reasoning
Pre-Assessment/Invitation to Learn
Air pressure in Utah changes constantly. On some days it is a high pressure. On other days it is lower pressure. We usually can’t feel it when it changes. But, when the air pressure changes, the weather changes too.
Tell the students that there is an instrument called a barometer that measures air pressure. Show them the numbers on a barometer - 28, 29, 30, and 31. When the needle on the barometer points to 30 and above, it tells us that we will have fair weather for a while with increasing temperature. When the needle on the barometer points to the numbers below 30, it tells us that there will be a change in the weather. The change could be increasing clouds, strong winds, temperature change and/or precipitation. Watching the barometer closely from day to day helps us predict what the weather will be like in the next day or two.
Tell the students that we will be making a barometer today. We will also be keeping a record of the changes of a barometer for the next two weeks. We will see that when the air pressure is high, we will have fair weather. We will also see when the barometer is low, there is a change in the weather with increasing clouds, strong winds, temperature change, and/or precipitation. (If you want to know about the first barometer, go to www.askjeeves.com. It will explain the mercury barometer and how it relates to the barometer we use today in our homes.)
Tell the students that today we are going to make a barometer. Then for the next
few days we are going to see if the air pressure rises or falls or stays the same. (This can
be done as a whole class, groups, or individually.)
Homework & Family Connections