Measuring weather

Today, barometers have become smaller, more accurate, and more dependent on electronics for both measurement, recording, and reporting compared to their more mechanical predecessors. You can even use some smartphones to measure pressure! A system is being developed to feed atmospheric pressure measurements from sensors in phones into weather forecast models. The better and more plentiful our observations are, the better our weather forecasting skill.

In our section, What causes the weather?, we learned that pressure is one of the main driving forces that cause weather to change and move, specifically that air tends to move from high to low pressure. This type of information tells us where the winds will blow and, when plotted on a map, shows the structure of many weather features.

Make your own barometer!
You can make your own barometer with the following materials:

• small coffee can or jar
• plastic wrap
• scissors
• straw
• index card
• rubber band

Cover the can or jar tightly with plastic wrap and hold it in place with the rubber band. The plastic wrap should make the can or jar air tight. Place the straw on the plastic wrap so that two-thirds of the straw is on the top of the can or jar. Tape the straw at the middle of the plastic wrap so it will not fall off. Next, place the can or jar on a table near a wall so that the straw is almost touching it. Tape the index card to the wall and make a mark with pencil where the straw is pointing. The straw is just used as a pointer. Come back as often as you want to see if the straw is pointing higher, or lower. You can shift the jar forwards to record the points over time on your index card.

High pressure makes the plastic wrap cave in and the straw go up. Low pressure will make the plastic puff up and the straw will go down.

Next page   -> in situ, surface observations, temperature

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