Calf being fed milk, thermogram footage. Thermography records the temperature of surfaces by detecting long-wavelength infrared radiation. The colours show variations in temperature. The scale runs from white (warmest), through yellow, orange, red and purple to blue (coldest). A colour-coded temperature scale is at right, ranging from 8 degrees Celsius (dark blue) to 34 degrees Celsius (white). This footage shows the calf's eyes and mouth radiating more heat than its head or the milk container.