Wherever you are - anywhere in the world - on June 21st consider taking and submitting a photo of a blank white piece of paper between 5:00 and 8:00 pm.
Your photo will not be just a picture of a pretty white piece of paper, it will be scientific data used to calculate earth’s albedo – the proportion of solar energy that bounces back out to space when it hits the Earth’s surface.
For three years Dr. Kathleen Gorski and her high school students at Wilbraham and Monson Academy near Springfield, MA have been snapping pictures of white paper and using them to measure albedo by comparing the white paper to the surrounding ground surface.
Now they are opening the project up to anyone who would like to participate!
Here’s how you can get involved:
- Stick a reminder in your calendar for Tuesday June 21, 2011 between 5:00-8:00 pm so that you don’t forget. (Note: I added this step to Kathleen’s instructions because I know I will need a reminder!)
- Put a white card (index or business cards work well) on any ground surface with the white side facing up.
- Snap a digital photo. No particular position for the camera is required. Just hold it, look down, and take the shot. (Kathleen has found that any camera will do - a cell phone or SLR will both work. And any resolution will be fine.)
- Email the photo to firstname.lastname@example.org
- Include the location (either your city and state or your latitude and longitude).
Kathleen and her students will analyze the data, comparing the response of the white card to the response of the ground surface in each photograph using ImageJ software and will depict the data points on a map. They will be posting the results this fall on a new project website and Kathleen will be presenting about the project to teachers at the National Science Teachers Association meeting in Hartford, CT in the fall.
Understanding albedo of the planet overall, and how albedo changes over time, tells us how much solar energy is being held by the planet, which is important for understanding climate.
Albedo is a measure between zero and one. Snow reflects almost all the sunlight that hits it so its albedo is close to one. Black asphalt reflects little sunlight, absorbing the energy and then radiating it out as heat, so it has an albedo close to zero. Averaged out over the whole planet, earth’s albedo is currently about 0.31 according to NASA and other scientific estimates. That means that about a third of the sunlight that gets to earth is reflected out to space.
The first year that Kathleen and her students did this project they had only about 50 photos, yet they were able to calculate an albedo of 0.33 for the planet using that data – not too far off.
Kathleen was inspired to start this project after taking a polar science education workshop at the University of Massachusetts. (Check out the learning activity: Measuring Albedo with Digital Cameras.) She also got fired up to find ways to include climate change in the classroom when she was an Einstein Fellow at the National Science Foundation Office of Polar Programs in 2007-2008. Reflecting on her experience as an Einstein Fellow, Kathleen said that, "believing climate change is the defining issue for today’s students, I made it my goal to find ways to incorporate it into traditional curriculum."
This post also appears on the Science for Citizens blog.