Earth and Environmental Science 11–12 · Year 11
Albedo: how surface colour changes the energy absorbed and the temperature reached
Module 3: Energy Transformations
The idea
A surface reflects a fraction of the sunlight it receives (its albedo) and absorbs the rest, so ice, forest, ocean and city roofs warm at different rates under the same Sun.
What you need
- four identical containers with lids painted matt black, white, mid-grey and covered in aluminium foil; a thermometer through each lid
- one desk lamp with a 100 to 150 W incandescent globe on a stand (UCAR activity), or direct sunlight on a still day
- light meter to measure reflected light from each surface at a fixed angle
- stopwatch
How to do it
- Measure the reflected light from each surface with the meter at the same distance and angle; albedo estimate = reflected / incident.
- Place the four containers at equal distance from the lamp and record each temperature every minute for 15 minutes.
- Plot temperature against time and read the rate of warming over the first 5 minutes.
- Rank surfaces by albedo and by warming rate and comment on the match.
- Relate the result to sea ice loss (dark ocean replacing bright ice) and to pale roofs in urban design.
What you should see
White reflects more than grey and grey more than black; foil reflects strongly but mostly in one direction, so its meter reading depends on the angle. Warming rate ranks opposite to reflectance, with the black container gaining the most degrees in 15 minutes (UCAR: dark-coloured materials warm most). A zero-dimensional energy balance, T = [S(1 − α)/(4σ)]^¼ with NASA’s solar irradiance S = 1361.0 W/m², gives an Earth of albedo 0.10 an effective temperature of 271.1 K against 255.1 K at the NASA Bond albedo of 0.294.
What changes
- What you change
- surface albedo
- What you measure
- rate of temperature rise
- What you keep the same
- distance from lamp
- container size and material
- starting temperature
- exposure time
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Dark surfaces attract heat.
- Albedo only matters at the poles.
Safety card
Hazards
- hot lamp
- hot foil surface
Controls
- lamp on a stand
- handle containers by the base
Note
A 100 to 150 W incandescent lamp is a heat source: keep it on its stand clear of the containers, follow the NSW Department of Education Chemical Safety in Schools (CSIS) package, Section 1, and record a RiskAssess risk assessment before the lesson.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Earth and Environmental Science Stage 6 Syllabus (2017), NESA; current, replaced by the 11–12 Syllabus (2025) from 2028EES11-10EES11/12-5EES11/12-6EES11/12-7
- Earth and Environmental Science 11–12 Syllabus (2025), NESA; to be implemented from 2028, not yet taughtEES-12-03
- Australian Curriculum v9No Australian Curriculum v9 code is listed.
Sources
The pages the author read to write this activity.
- www.nsw.gov.au/education-and-training/nesa/curriculum/science/earth-and-environmental-science-stage-6-2017
- scied.ucar.edu/activity/looking-surface-albedo
- nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
- education.nsw.gov.au/content/dam/main-education/asset-management/chemical-safety/1._Section_1_-_General_information_for_all_staff.pdf