Saturday, January 26, 2019

Associating the color of an object with its light reflection (Science Kitchen - Jan 2019)

Twenty five middle school (6th-8th grade) students from Wyoming learned how the color of an object can be associated with the amount of light reflected by it in the different regions of the electromagnetic spectrum.  As part of the hands-on activity organized by Science Kitchen, they measured the amount of light reflected by blue and green color materials using an ALTA II Spectrometer (below).

Higher reflection for each object recorded in the wavelength that corresponded to their color, i.e., blue material reflected most in the blue region (470 nm) of the spectrum.  Following the hands-on activity, WyomingView PI demonstrated how the same principle of light reflection can be applied to satellite and aerial images for monitoring water clarity of lakes.

Landsat 5 Thematic Mapper image acquired in 2011 (above) shows the spread of algal bloom in Lake Erie.  Light reflection in the lake covered by floating algae (shades of green) varies from the rest (dark blue), which can be used for monitoring water quality.

Additional details about this image and the algal bloom problem captured in it can be found at NASA's Earth Observatory website (