Objective:

This demo will help to explain what a barometer is and how it can be used to help predict the weather.

Standards:

Structure of the Earth System (atmospheric composition and properties and different elevations; clouds – formation and impact on weather and climate), Understanding About Science and Technology (scientists use tools; technological designs have constraints; science often advances with the introduction of new technologies), and Science and Technology in Local Challenges (benefits of science and technology – these benefits are not available to all people).

Materials:

plastic bowl, two liter pop bottle, and tap water.

Procedure:

Fill the plastic bowl about halfway with tap water.

Fill the pop bottle with water so that it is about three – quarters full.

Place and hold your hand over the opening of the pop bottle as you turn it upside down.

Place the opening of the upside down bottle directly on the bottom of the bowl.

Carefully and quickly remove your hand from the bottle.

Observe and discuss what happens.

Science behind It:

As you observe the pop bottle, you should see the water level inside the bottle either rise or fall depending on the conditions of the surrounding air at the time. This happens because the changing pressure of the outside air on the water in the bowl causes the water level in the bottle to change. When air pressure rises, water is pushed up into the bottle and when air pressure falls, the water level in the bottle falls as well. These conditions assume that the pressure inside of the bottle remains the same, as it should if the demo was conducted properly. This pop bottle barometer can be used to help predict future weather conditions because high pressure usually means better weather, while low pressure typically indicates colder temperatures or rainfall. Scientists use barometers (much more sophisticated ones) to help understand and predict weather and climate patterns. Scientists then use this information to prepare citizens for the upcoming weather events.