Number of Cells developed during the Life-time of a Thunderstorm

Abstract

THE observed ‘cyclic’ variation in the rate of flashing in an active thunderstorm is traced to the fact that a decaying cell can give rise to a new cell and that this process can go on until the thunderstorm itself finally decays^1–5. The life of a cell is estimated from direct and indirect experiments to be about 30 min. But no practical method appears to have been devised to estimate the number of cells developed during the entire life-time of a thunderstorm. This communication describes how this useful information can be obtained from investigations of the rates of flashing. Such work requires the recording of all types of flashes, as the relative percentages of the different types of flashes can vary during the life-time of a thunderstorm, and from thunderstorm to thunderstorm. As the lightning-flash counters available at present do not meet this requirement⁶, a high-frequency counter⁷ was developed as a prototype of the noise meter previously described^8,9.