Number of fires occurring monthly for France, Italy, Spain, Portugal and Greece from July 1996 to August 2007. These data are based on results from the Along Track Scanning Radiometer (ATSR) on ESA’s ERS-2 satellite, launched in 1995, and the Advanced Along Track Scanning Radiometer (AATSR) on ESA’s Envisat satellite, launched in 2002.
These twin radiometer sensors work like thermometers in the sky, measuring thermal infrared radiation to take the temperature of Earth's land surfaces. Temperatures exceeding 308º K at night are classed as burning fires.