GRAND RAPIDS — High pressure and low pressure are terms we hear all the time in our weather forecasts, but do we know how pressure is measured? Meteorologists use a lot of different instruments to measure all the different aspects of the weather. In regard to pressure they use something called a barometer to measure the levels. Today we are going to build one to use at home! Here is what you need to get started.
What you need:
- Short wide-mouth glass jar
- Plastic straw
- Construction paper
Step 1: Cut off the smaller end of the balloon and stretch the leftover wide part over the mouth of your jar
Step 2: Prep your straw. If you are using a bendy straw cut off the bendy part as we just need a long, straight part of the straw.
Step 3: Cut an arrow out of cardstock to fit on the end of the straw. Make sure to keep in mind we will be placing the stem of the arrow inside the straw.
Step 4: Glue or tape the arrow inside the straw and then glue or tape the entire arrow and straw piece on top of the balloon on the jar.
Step 5: Take a piece of construction paper and write the words high and low on it. Then place it somewhere that’s stationary and put it directly behind the jar
Step 6: With your marker draw a line where your arrow is right now. This sets your base pressure base. Now watch and observe over the next several days, weeks or months.
Start watching this from day to day and you’ll notice the pressure changing. When the pressure is high the air around the jar pushes down on that balloon then pushing the tip of your arrow up. When the air pressure is low the air inside the jar is pushing up on balloon then pushing the tip of your arrow down.
Check your barometer at the same day everyday and notice where the arrow is pointing. Make connections with what is going on with the weather. How is it different from yesterday? Do you think it will change tomorrow? How? Pressure controls a lot of how our weather turns out. Changing pressure changes how the wind is moving through the atmosphere.
High pressure typically means a clear sky and calm weather because the air in the atmosphere is moving down. This causes a really stable air mass which makes it hard for clouds or rain to form. Low pressure typically means unsettled weather with more clouds, rain, storms and even snow because the air in the atmosphere is rising. This causes really unstable air mass which leads to more of the clouds and storms.
Send our meteorologist Candace Monacelli your pictures doing this experiments at home! She will feature future meteorologists on my Facebook page daily!