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A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ''ground-based'' systems using multiple antennas, ''mobile systems'' using a direction and a sense antenna in the same location (often aboard an aircraft), and ''space-based systems''. The device was invented in 1894 by Alexander Stepanovich Popov. It also was the first radio receiver in the world. Ground-based and mobile detectors calculate the direction and severity of lightning from the current location using radio direction-finding techniques together with an analysis of the characteristic frequencies emitted by lightning. Ground-based systems use triangulation from multiple locations to determine distance, while mobile systems estimate distance using signal frequency and attenuation. Space-based lightning detectors, on artificial satellites, can locate range, bearing and intensities by direct observation. Ground-based lightning detector networks are used by meteorological services like the National Weather Service in the United States, the Meteorological Service of Canada, the European Cooperation for Lightning Detection, and by other organizations like electrical utilities and forest fire prevention services. == Limitations == Each system used for lightning detection has its own limitations. These include: * A ground-based lightning network must be able to detect a flash with at least three antennas to locate it with an acceptable margin of error. This often leads to the rejection of cloud-to-cloud lightning, as one antenna might detect the position of the flash on the starting cloud and the other antenna the receiving one. As a result, ground-based networks have a tendency to underestimate the number of flashes, especially at the beginning of storms where cloud-to-cloud lightning is prevalent. * Since they use attenuation rather than triangulation, mobile detectors sometimes mistakenly indicate a weak lightning flash nearby as a strong one further away, or vice versa. * Space-based lightning networks suffer from neither of these limitations, but the information provided by them is often several minutes old by the time it is widely available, making it of limited use for real-time applications such as air navigation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lightning detection」の詳細全文を読む スポンサード リンク
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