Chimpanzee hooting. Thermographic footage of a chimpanzee (Pan troglodytes) and the blasts of air exhaled as it emits a hooting cry. A thermogram shows variation in temperature on the surface of an object, measured by the long-wave infrared radiation it emits. The temperature scale is colour-coded from black (cold) through purple, blue, green and yellow to red and white (hottest). This thermogram footage shows that the exhaled air is warmer than its surroundings as it has recently been inside the body.