Monday, November 18, 2013

Easy, Crude Barometer

Stretch a balloon over the open end of an empty glass jar, secure it with a rubber band, and tape a toothpick or popsicle stick to the top (with a little more than half of the stick stretching out over the edge of the jar).  As the air pressure changes the stick will move.

Yesterday 80 tornadoes hit the Midwest.  In the South we were, thankfully, spared.  We had a few frightful moments of high winds, rain and lightning, but nothing too bad at our house.  As luck would have it, our 4th grader, "Peel," has been studying weather and the atmosphere in science lately.  She's learned that atmospheric pressure changes signal a change in the weather, and in our case we noticed a difference in the pressure yesterday (during the storm) versus this morning (when it was clear).

We had just finished this crude barometer before the storms hit last night (we marked the location of our toothpick on the index card taped to the wall) when the pressure was low.

Can you see the tiny dot under the toothpick, to the right of the red line?

This morning the air pressure was higher, which often happens when a cold front has moved over an area.  The higher the air pressure, the higher the stick will reach.  Sure enough, we had oddly warm weather yesterday, and this morning the air was back to chilly.  If you are expecting a storm, wash out a jar and try this yourself!

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