The map "Die Welt ist bunt" (The World is Colorful) divides the earth's surface into 10 climate categories. The reddish orange describes the hot, burned soil of the desert. Yellowish orange depicts semi-desert and desert steppe. Green tones, varying between a green-brown (coniferous woodland), green-yellow (agricultural land) to a green-blue (rainforest), stand for humid areas.
Further remarkable examples of naturally colored reliefs:
"Relief de la Suisse" by Eduard Imhof
"Walensee" by Eduard Imhof
"Europa map" by Hal Shelton
"Natural Earth II" by Tom Patterson
"Natural Earth Globe" animation by Adrian Weber
"Grand Teton" and "Kenai Fjords National Park" by
Tom Patterson, who combines relief shadings and aerial photographs. For more details, see Patterson's paper "Getting Real: Reflecting on the New Look of National Park Service Maps"