The top photograph was acquired during a flight from McMurdo Station aboard a Basler aircraft on November 30, 2017. It shows ice flowing from the Transantarctic Mountains, a range that runs the length of the continent and separates West Antarctica and East Antarctica. The dark blue areas are where melt water—spurred by days of abundant sunshine and light winds—has flowed down into lower spots and then refroze. Refrozen melt ponds fill almost every ripple in the top-middle of the image, and along the direction of flow of the glacier visible in the foreground.

Paler blue areas indicate places where uncompressed snow has blown away to reveal blue ice. Ice is generally blue for the same reason that water is blue. Namely, the bond between oxygen and hydrogen atoms in the water molecule, frozen or liquid, absorbs longer wavelengths of visible light and leaves behind the shorter (blue) wavelengths. Dense glacial ice that has been compressed and the air bubbles are squeezed out will appear even bluer.