blizzards and winter weather

The Earth is surrounded by an atmosphere which is about 80 miles thick. All this air produces a pressure of about 14.7 pounds per square nich at sea level. This pressure is called atmospheric pressure, and everything on Earth experiences this pressure. Atmospheric pressure is measured using a device called a barometer. There are two basic types of barometers: a mercury and an aneroid barometer.

Make a Barometer

The purpose of this experiment is to simulate how a mercury barometer works. A mercury barometer consists of a tube containing mercury that is inverted into a basin containing more mercury. In this activity we will use water instead of mercury.

stuff you need

16 oz glass juice bottle with label soaked off

One-hole stopper to fit the opening

Transparent plastic straw

Colored water

Clear plastic tape
Index card
1. Fill the bottle 2/3 full of colored water

2. Insert the plastic straw through the stopper about 2/3 of the way up the straw.

3. Place the long end of the straw into the bottle (the end should be below the surface of the water in the bottle), and fit the stopper snugly into the bottle opening

4. Blow some air into the straw until water rises above the stopper

5. By attaching a card to the straw above the stopper, and recording the water level, observe how the varying air pressure causes the water level to rise and sink.

Increased air pressure pushes the level of the water in the straw down, while decreased air pressure allows the water in the straw to rise. Please note: this barometer only works effectively when the air temperature remains constant.