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Activities

Evaporation, condensation, particle and cloud formation

 T1 Water in the air

Go to the following interactive -> QUIZ <- and test your knowledge about water and its role in the atmosphere.

 T2 Vapour pressure and evaporation

Put four small petri dishes on a moderately warm heating surface (40-50°C) at the beginning of your lesson. Fill them with 10 ml each of 

1) water
2) water with a bit of dissolved table salt
3) ethanol 
4) salad oil.

Observe what happens during the lesson. Can you sort these compounds with respect to their volatility?

Please enter in the order of decreasing volatility (Water, Salt, Ethanol, salad oil):

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At the end of the lesson, if it is not yet evaporated, switch on the heating plate and heat up the petri dish with the salty water. What happens? What can you conclude about salts floating in the atmosphere? Give an answer in 3-4 sentences.
 

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 T3 Discuss:
 
Why do scientists investigate particle formation in the forest? What do you think is wrong, what is correct? Explain in a short text of about 10 sentences your answer.

A: Particles in the forest are a source of severe air pollution. It might be a health risk to walk in the forest and we need to find out more about it.

B: Particles are important for cloud formation. Since the cloud properties are important for our climate, scientists try to understand how cloud characteristics depend on particle formation.

C: Organic particles settle on the forest ground and fertilize other plants. Scientists would like to know more about particles in order to produce better fertilizers for agriculture.

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 T4 Special task: Find out about mistakes in scientific interpretation!

A group of biologists, specialising in ocean research, built up a measurement site at a nearly unpopulated coastline. They often observed higher values of sulphur dioxide (SO₂) during the night and concluded that plants in the ocean release more SO₂ at night time. An experienced climatologist saw the results and smiled. He gave them the following hints:

1. Think over what you learned in physics about heat capacity of water compared to other liquid and solid matter!
2. Read in the following text the paragraph with the title ‘General Circulation’:
   http://www.atmosphere.mpg.de/enid/2t7.html 
3. Have a look on the following map on the left, where your measurement point is located (red dot) and consider the location of a power plant which burns coal without any sulfur filter.

Explain in 6-8 sentences, why the heat capacity of water is relevant for the local weather factors near the coast and why the location of the measurement point was not well chosen.