Worksheet 2.2

1. What is:

a) cloud processing?

b) dry deposition?

c) wet deposition?

2. Aerosols and health

a) Why are small particles more dangerous to inhale than bigger ones?

b) What other property determines how hazardous a particle is to our health?


1. Lungs.
Image: Microsoft clipart

3. Experiment: Making a cloud in a bottle

You will need:

  • one transparent plastic bottle (at least 1.5 litres in size) with a bottle cap
  • hot water
  • matches


  1. make sure the bottle is clean inside
  2. pour hot water into the bottle to a depth of about 3 cm
  3. close the bottle 
  4. rotate the bottle around so that the whole of the bottle is wet inside
  5. pour out the water
  6. light a match and as soon as the tip of the match has finished flaring, blow it out 
  7. let the smoke from the match enter the bottle (if you squeeze the bottle and hold the match close to the opening while you remove the pressure from the bottle the smoke from the match will be drawn into the bottle)
  8. close the bottle
  9. increase the pressure in the bottle by squeezing it. 

Can you see a cloud appearing in the bottle? If you remove the pressure in the bottle by loosening the cap, the cloud will disappear.

Can you explain this? Smoke is made up of a large number of very small particles. Why do you need the smoke to make the cloud in the bottle.

About this page:
Authors: Ellen K. Henriksen and Camilla Schreiner - University of Oslo - Norway. Scientific reviewer: Justine Gourdeau - LaMP Clermont ferrand - France - 2004-01-13. Last update: 2004-03-27.

Last modified: Friday, 17 January 2020, 12:51 PM