Chameleon turquoise, and purple. Chameleon skin has a superficial layer which contains pigments, and under the layer are cells with guanine crystals. Chameleons change colour by changing the space between the guanine crystals, which changes the wavelength of light reflected off the crystals which changes the colour of the skin. Colour change in chameleons has functions in camouflage, but most commonly in social signaling and in reactions to temperature and other conditions. The relative importance of these functions varies with the circumstances, as well as the species. Colour change signals a chameleon's physiological condition and intentions to other chameleons. Chameleons tend
Snow camouflage camouflage was not limited to paint: tracks left in the snow were to be obliterated, vehicles parked in cover, headlights covered with white fabric, shelters constructed, or else vehicles covered with white fabric, or dark fabric scattered with snow. Later in the 20th century, as disruptively patterned uniforms became widespread, winter variants of patterns such as "Flecktarn" were developed, the background colour (such as green) being replaced with white to form a "Schneetarn" (snow camouflage pattern). Aircraft deployed in winter have sometimes been snow camouflaged, as with Sepecat Jaguars on exercise in Norway. Snow camouflage is manufactured commercially for use