On 19 February 2014, the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Nasa’s Aqua satellite flew over the Great Lakes and captured this striking image of the heavily frozen Great Lakes – one of the hardest freeze-ups in four decades.
This false-colour image uses a combination of shortwave infrared, near infrared and red (MODIS bands 7,2,1) to help distinguish ice from snow, water and clouds. Open, unfrozen water appears inky blue-black. Ice is pale blue, with thicker ice appearing brighter and thin, melting ice appearing a darker true-blue. Snow appears blue-green. Clouds are white to blue-green, with the colder or icy clouds appearing blue-green to blue.
Image credit: Nasa/Jeff Schmaltz, MODIS Land Rapid Response Team, Nasa GSFC