Abstract
In this paper and the subsequent papers it is assumed that the ionisation of the atmosphere is merely caused by the radiation from the sun. Assuming that the number of pairs of ions produced by the radiation per cubic cm and per second is proportional to the loss of energy of radiation, we meet with an integral but this is not integrable as it is reduced to the form dr. Hence the author tried to integrate this by the graphical method and obtained some results concerning the height of maximum ionisation and the relative number of pairs of ions. The height of maximum ionisation is minimum when the radiation is perpendicular to the horizon and it increases slowly as the inclination of radiation to the horizon deceases. The shape of the curve of the relative number of pairs of ions is almost the same as that of the perpendicular radiation if we consider only the side of the earth facing the sun, hence approximately Pedersen's equation is able to be used there.
