Dark and Bright

This image of the polar region illustrates the effect of the sun on 
polar frost. The highstanding ridges have lost all their frost cover, 
while the lows shaded by the ridges still have a bright frost cover

This image of the polar region illustrates the effect of the sun on polar frost. The highstanding ridges have lost all their frost cover, while the lows shaded by the ridges still have a bright frost cover