Abstract
Rotational temperature rise of N2 molecules in the repetitive positive streamer corona in a point to plane gap in air under DC voltage is measured with high resolution in space and time. In the pair of the successive luminous waves in each stramer, the gas temperature rise of a few hundred degrees is observed only in the secondary wave over its luminous period. The gas temperature rise in such a small level seems to bring small effect on the sparkover of the whole gap following to the secondary wave. The mechanisms of the gas heating and cooling, the development of primary and secondary waves and of the whole gap sparkover are discussed.