The preferred term for the middle wavelength ranges of the infrared region extending roughly from 3 µm at the end of the near infrared, to about 15 or 20 µm where the far infrared commences. In practise the limits represent the envelope of energy emitted by the Earth behaving as a greybody with a surface temperature around 290° K (27° C). Seen from any appreciable distance, the radiance envelope has several brighter bands corresponding to windows in the atmospheric absorption bands. The thermal band most used in remote sensing extends from 8 to 14 µm.