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 advised either all-white using zinc white or titanium white paint for level, open country, or disruptive two-colour winter camouflage for areas with more variety including "forests, underbrush, small settlements, thawed patches of earth". The two colours could be achieved either by leaving around a quarter to a third of the vehicle's summer camouflage uncovered, or by repainting the whole vehicle in white with dark gray or gray-brown spots. Units were advised not to paint all their vehicles identically, but to have some tanks all white, some in white with green stripes, and some in white and gray or gray-brown. Winter