Lesson Plan: Aerosols and Climate

Here is a step-by-step guide to using this lesson plan in the classroom/laboratory. We have suggested these steps as a possible plan of action. You may customize the lesson plan according to your preferences and requirements.

Step 1: Topic introduction and discussion (Reading)

1. Use a reading, “Atmospheric Aerosols: What Are They, and Why Are They So Important?” by the Langley Research Centre, NASA, to discuss in detail what atmospheric aerosols are and what are their main sources. Use the reading to explain in detail how aerosols can affect climate and can cause both heating and cooling on the Earth’s surface.
2. Emphasize that volcanic eruptions are amongst the largest sources of atmospheric aerosols. Using examples discussed in text, explain how volcanic eruptions have affected Earth’s climate in the past, due to the large-scale dispersal of particulate matter and the release of greenhouse gases into the atmosphere.
3. Further, describe how the other main sources of aerosols- dust and anthropogenic sources like smoke particles and sulfate aerosols from the burning of fossil fuels- can also affect climate.
4. Describe how sulphate aerosols are formed in the atmosphere when sulphur dioxide reacts with water to form fine liquid droplets of sulphuric acid and solid particles of salts of sulphuric acid. Discuss how the concentration of human contributed sulfate aerosols have increased in the industrial age and how they could possibly affect Earth’s climate.
5. Finally, explain how aerosols are used as tracers to study global atmospheric patterns.
6. Go to the Reading

Step 2: Use a visualization tool to explain (Video)

1. Next, use an animated video, “Aerosol Nanoparticle Formation” by Aerosol Physics and Environmental Physics- Winkler Group, University of Vienna, to help students to visualize the interactions of aerosol particles and gas molecules in the atmosphere.
2. Use this video to explain how some of these interactions result in molecular aggregates in the atmosphere, on which water condenses to form water droplets resulting in cloud formation. Clouds both absorb light from the sun and form a barrier for heat loss from the Earth’s surface thereby affecting the Earth’s radiation energy balance.
3. Therefore, discuss how aerosols have an indirect effect on climate due to their role in aiding cloud formation.
4. Go to the Video

Step 3:  Conduct a classroom activity

1. Conduct this enquiry-based classroom activity, “Volcanoes and Global Warming” by Purdue University to enable students to study data of emissions from volcanic eruptions.
2. Firstly, engage the students in a discussion of what kind of material is ejected into the atmosphere as a result of volcanic activity i.e. ash (fine dust) and several gases. Use the text to specify that water vapour, carbon dioxide (CO₂) and sulphur dioxide (SO₂) are the main gases released. Of these, water vapour and carbon dioxide are greenhouse gases and can directly contribute towards warming of the Earth’s surface.
3. Sulphur dioxide, on the other hand, has an indirect effect on climate by forming sulfate aerosols. Emphasize on the role of these sulfate aerosols on climate as they directly absorb or reflect light energy or indirectly, through cloud formation, cause heating or cooling on the Earth’s surface.
4. Using the data provided, instruct students to draw bar graphs to compare the percentages of the types of gases released from volcanic eruptions in disparate geographic locations.
5. Use the ‘Extend Your Thinking’ section to analyse two cases of volcanic eruptions in the past and engage the students in a discussion about the impact of sulfate aerosols on the global climate.
6. Go to the classroom activity

Use the tools and the concepts learned so far to discuss and determine answers to the following questions:

1. What are aerosols and what are the sources of atmospheric aerosols?
2. How do atmospheric aerosols aid in the formation of clouds and precipitation?
3. Explain how atmospheric aerosols can have a cooling or warming effect on the planet?
4. What kind of atmospheric aerosols are emitted during volcanic eruptions?
5. Which are the main atmospheric aerosols produced by anthropogenic activities and how can they affect climate?

The tools in this lesson plan will enable students to:

1. what aerosols are and what are their main sources
2. the importance of the presence of aerosols in the atmosphere
3. the role of aerosols in cloud formation and precipitation
4. the mechanisms of the cooling or heating effects of atmospheric aerosols on the Earth’s surface
5. the possible effect of various types of atmospheric aerosols on climate

If you or your students would like to explore the topic further, these additional resources will be useful.