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 an Aneroid Barometer

The purpose of this experiment is to simulate how a aneroid barometer works. An aneroid barometer contains no liquid, but instead utilizes a small flexible metal box called an aneroid cell. In this activity we will use a jar and a balloon instead of a real aneroid cell.
stuff you need

Wide mouth glass jar or can

Round (rather than oblong) balloon

Rubber bands

Straw
Graph paper
Tape
Rubber cement glue
1. Blow up the balloon once and then let out the air

2. Cut off the neck (the bottom 1/4) of the balloon

3. Stretch the other part over the mouth of the jar, and secure with a rubber band

4. Cut one end of the straw 45 degrees to make a pointer.

5. Glue the other end to the center of the stretched balloon

6. Tape the graph paper on the wall, and place the barometer so that the straw nearly touches the graph paper.

7. Mark the height that the straw "touches" the paper. Also record the time and date.

8. Observe several times daily for a few days if possible.
Increasing air pressure makes an indentation in the center of the balloon, which forces the free end of the straw up. When the air pressure decreases the balloon comes back up lowering the free end of the straw. Greater air pressure is usually a sign of clear weather, while lower air pressure usually signals a chance of precipitation. Please note: this barometer only works effectively when the air temperature remains constant.