| 摘要 |
PROBLEM TO BE SOLVED: To immediately confirm lightning distance by a device in hand by detecting light and voice with a photodetector and a microphone, respectively, by calculating the distance according to the time difference between both the detection time, and by comparing with past lightning distance danger data. SOLUTION: Light due to lightning is detected by a light detection means 10 of a photodetector such as a visible photodiode for converting to an electric signal, and at the same time the clocking of a clocking means 16 such as a stopwatch is started. Lightning sound after the lightning light occurs is detected by a sound detection means 13 such as a microphone for converting to the electric signal, and at the same time the clocking means 16 is stopped. The clocking means 16 executes start and stop, and clocks time from the generation of lightning light to that of lightning sound. An operation means 17 calculates sound velocity and the time of a clocking result for calculating distance. A comparison means 20 compares the calculation result of lightning generation distance with an accumulated lightning danger distance reference value data. A warning means 21 issues warning by voice or the like when it is judged that a measurement distance calculation result is danger distance according to the comparison result of the comparison means 20.
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