Teacher guide
Teacher guide Evaporation experiments Drought Drought is sometimes described as an imbalance between precipitation and evaporation over a long period of time. During a drought, evaporation from open bodies of water generally increases, and the land is drier than usual. Moisture still evaporates into the atmosphere, but not enough to form rain clouds. This effectively causes the land to ‘bake’ and removes additional moisture, which further intensifies dry conditions. As average temperatures rise due to climate change, the Earth’s water cycle accelerates as a result of an increased evaporation rate. This increased evaporation rate makes more water available in the air for precipitation in some parts of the world, and creates drier land areas in other parts – exacerbating both flooding and drought. In this project, students will design an experiment to measure the ongoing evaporation of water set up with different variables, e.g. water alone, water in different types of soil, water in soil with plants growing in, simulating different weather conditions, and so on. They will use their results to assess what factors may affect evaporation. Prompts • What different variables will you measure? What environmental conditions will you need to control? Support students to think about their methodology and how to create fair test conditions. • Do you have any innovative ideas about how we could slow down evaporation? Encourage students to be creative and test out different variables. • What do your results tell you? Which factors affect the speed of evaporation? How could your research be used in the development of drought mitigation solutions? Encourage students to think about the wider purpose of their project and how their research could be taken further. 16
Student brief Evaporation experiments Drought (Physics, evaporation, drought, climate change) Have you ever wondered if we can slow down evaporation? Imagine you work for an organisation that conducts drought research. You are concerned about the pattern of more intense and longer-lasting droughts in some regions, and how this will evolve in the future. You want to find out if all types of land have the same rate of evaporation, and investigate what kinds of changes might help mitigate the severity of drought. You are particularly interested in finding out how land use and land cover (e.g. plants, forest, grass and crops) affect the rate of evaporation. Getting started Start by planning out your experiment. You will need to decide what different variables you will test, e.g. water alone, water in different types of soil, water in soil with plants growing in, and so on. Think about how you will measure the speed of evaporation. Things to think about • How many different tests will you run? • How will you measure the evaporation rate? • How often will you take measurements? • How will you create a controlled environment for your testing? • As well as soil types and the presence of vegetation, what else might be interesting to test? • Is there a way you could test out the impact of different weather conditions on the rate of evaporation? • How will you record and present your results? • How could this project be taken further? If you were trying to engineer drought mitigation solutions, what would be the next step? Useful resources • UKCEH Water Resources Portal https://eip.ceh.ac.uk/hydrology/water-resources/ • Evapotranspiration and Droughts https://geochange.er.usgs.gov/sw/changes/natural/ et • UKCEH: What is a drought? https://www.ceh.ac.uk/news-andmedia/blogs/what-is-a-drought • Royal Meteorological Society https://rmets.onlinelibrary.wiley.com/doi/abs/10.10 02/wea.67 Health and safety To avoid any accidents, make sure you stick to the following health and safety guidelines before getting started: • Find out if any of the materials, equipment or methods are hazardous using http://science.cleapss.org.uk/Resources/Student- Safety-Sheets/ to assess the risks. (Think about what could go wrong and how serious it might be.) • Decide what you need to do to reduce any risks (such as wearing personal protective equipment, knowing how to deal with emergencies and so on). • Make sure there is plenty of space to work. • Clear up slip or trip hazards promptly. • Make sure your teacher agrees with your plan and risk assessment. 17
