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Clouds in a Bottle
How clouds formYou will need:
- A plastic bottles with a lid (ideally at least 1litre)
- Water
- Matches
- Thermometer small enough to go into the bottle
What to do:
- Put a thermometer in the bottle and close the lid tightly. Record the temperature, then see what happens to it as you squeeze the bottle. You should see the temperature increase as the bottle is squeezed and the air inside it is compressed.
- Now fill the bottle with a little warm water, and shut the lid again. Now what happens when you squeeze the bottle? As the warm water evaporates, the amount of water vapour in the air in the bottle increases. When you release the bottle, the pressure, and temperature in the bottle drops. However, you should not see any clouds forming despite the fact that the air in the bottle is almost certainly saturated with water vapour.
- Now open the bottle, and light a match. Hold the match near the mouth of the bottle, then blow it out, holding the smoking end of the match in the bottle for a few seconds before quickly closing the lid tightly. Squeeze and release the sides of the bottle a few times. Now what happens when you squeeze the bottle hard for a few seconds and then suddenly release the bottle? You should see a cloud forming in the bottle when you release it, as the water vapour now has small particles (smoke, soot, ash), or Cloud Condensation Nuclei, to condense on.
How this relates to the atmosphere
Clouds can only form when the air is saturated with water vapour and when there are condensation nuclei present. Cloud seeding experiments introduce extra Cloud Condensation Nuclei to the atmosphere, to influence the number and size of raindrops in a cloud.More Information
Condensation:
http://www.ace.mmu.ac.uk/eae/english.html and select 'atmosphere' and 'clouds'
Encyclopaedia of the Environment
Cloud condensation nuclei:
http://en.wikipedia.org/wiki/Condensation_nuclei
Cloud seeding experiments:
http://en.wikipedia.org/wiki/Cloud_seeding
http://www.sciencemuseum.org.uk/antenna/climatechange/Cip5/231.asp
http://www.usatoday.com/news/world/2006-06-29-china-rain_x.htm