Excerpt from Hands-On Science.
Objective
Use this activity to help your students understand some of the many variables that must be taken into account in a study of weather and to appreciate its importance in our lives.
Materials Needed
• One 2-liter bottle with cap
• Kitchen matches
Procedure
1. Put a small amount (about 1/4 cup) of water into the bottle.
2. Light a match. Hold it down in the bottle to make smoke.
3. Put the lid on the bottle.
4. Shake the bottle to add moisture to the air inside the bottle.
5. Squeeze the bottle, then release it quickly and observe what is inside the bottle.
6. Squeeze and release several times. What’s happening inside the bottle?
7. Share your observations and ideas with others who are interested in this activity.
For Problem Solvers
Experiment with different temperatures of water and different amounts of smoke in the bottle for this activity. Also, do some research and learn all you can about how clouds form in the atmosphere. What causes changes in pressure in the atmosphere, and how does this affect temperature? And what do pressure and temperature have to do with cloud formation?
Teacher Information
Air pressure increases the temperature of the air. As air temperature increases, the air is able to contain more moisture. Squeezing the bottle increases the temperature of the air inside the bottle. Releasing the pressure on the bottle reduces the temperature of the air and decreases the ability of the air to hold moisture. The smoke particles that are suspended in the air act as condensation nuclei, and moisture condenses, or collects, around them. Each time you releasethe pressure a cloud forms, and when you squeeze the bottle the cloud disappears.
Smoke and dust particles in the atmosphere act as condensation nuclei when moisture content is high and temperature drops. Changes in atmospheric pressure create changes in atmospheric temperature, similar to the way these changes occur in the mini-atmosphere in the bottle.
