Lesson 8 - Understanding Atmospheric Pressure - Barometer

How to Build a Barometer

These simple materials will make a functioning barometer using water:

Materials:

• Saucer
• Water
• Plastic soda bottle
• Index card

Build the barometer using the following steps:

a) Fill the saucer halfway full of water.

b) Fill the bottle 3/4 full of water.

c) Cover the mouth of the bottle with your thumb, and tip it over.

d) Submerge the mouth of the bottle in the water in the saucer, or as nearly as possible.

e) Remove your thumb quickly, so as little water as possible escapes from the bottle.

f) Tape a strip of the index card on the outside of the bottle.

g)\Mark the index card at the water level.

If the water level goes up, the atmospheric pressure is increasing, and cooler and/or dryer weather can be expected.

If the water level goes down, the atmospheric pressure is decreasing, and warmer and/or wetter weather can be expected.

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