Study On The Evolution Properties Of Channel Temperature And Conductivity During The Lightning First Return Strokes

The time-resolved spectra in the range of 400-900 nm for the first return strokes of could-to-ground lightning return stroke process were obtained by a slit-less spectrograph with a high-speed camera as recording system at the Qinghai plateau of China. The temperatures of the lightning core current channel and peripheral glowing channel have been calculated respectively;. Combining with the transport theory of air plasma, we have obtained the electrical conductivity in discharge channel, and discussed the evolution characteristic of channel temperature and the electrical conductivity. The results show that the temperature of lightning core current channel is about 5000-7000 K higher than that the peripheral of channel. In the return stroke process, the time of keeping the high temperature in the discharge channel is far greater than the exist time of the peak discharge current, the temperature of the lightning core current channel maintaining above 20000 K as the return current decreasing slowly in the hundreds of microseconds. And this characteristic is a major cause of thermal effect which leads to the lightning disaster.The results in this work will give some reference date for further study on energy transmission, lightning discharge current, lightning physical mechanism in lightning discharge process.