How are satellite sensors able to detect forest fires?
Satellite sensors record the intensity of electromagnetic radiation from Earth in various spectral wavelengths or channels. These wavelengths can be classified into general ranges, including the visible (0.4–0.7 µm), near-infrared (0.7–1.3 µm), mid-infrared (1.3–3.0 µm), and thermal infrared (3.0-100 µm). Fires and other sources of intense heat can be detected if a sensor includes a channel near the 4-µm range, which is highly sensitive to thermal radiation emitted from objects hotter than about 200°C. For more background on satellite remote sensing see the Fundamentals of Remote Sensing tutorial on the Canada Centre for Remote Sensing (CCRS) web site.
