Introductory techniques

Albedo is the amount of light reflected from a surface. Surfaces with high albedo, like ice and snow, are light in colour and reflect most incoming sunlight, while surfaces with low albedo, such as oceans and forests, are dark in colour and absorb much more energy.

One of the most important feedbacks in climate change is the ice–albedo feedback. As global temperatures rise due to increased greenhouse gases, ice and snow melt, exposing darker land or ocean surfaces. These have a much lower albedo, so they absorb more heat, which accelerates warming and causes even more melting—creating a self-reinforcing or positive feedback loop.

Download ‘Albedo: a reflectance app’ onto a phone. Follow the instructions on the app and record the albedo of some control surfaces, such as grey card, sky or water.

Climate change and sustainability

Before students measure albedo, they should record the environmental conditions of the places that they are going to survey. For example, air temperature, rainfall and sunshine duration as well as an estimate of the % covered by different surfaces.

Students could measure different temperatures and albedos. For example, they could measure them along a transect in an urban area to consider the effects of the urban heat island. Alternatively, measurement in different areas could be used to consider the impact of urban greening and urban design on temperatures in cities.

For further information about measuring albedo in urban areas, see Creative Fieldwork 2 by Janine Maddison and Robyn Landy.

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The Geographical Association (GA) has worked closely with the Field Studies Council (FSC) to develop these resources.