Discussion on the electrical state of the upper atmosphere

Abstract

Sir Ernest Rutherford: During the last few years there have been a number of new lines of attack bearing on the problem of the constitution and electrical state of the upper atmosphere. The work of Lindemann and Dobson on falling meteors has suggested that the pressure of the upper atmosphere calculated on the ordinary theory is seriously in error, and they conclude that the atmosphere above the isothermal layer of temperature about 220° A. rises to about 300° A. For heights of the order of 100 km. the pressure may be 10 to 100 times the ordinary calculated value. If these deductions are valid they must be taken into account in considering the amount of ionization at various heights due to the sun’s rays, and of the ionization due to the very penetrating radiation in the atmosphere brought to light recently by the work of Kolhörster and Millikan. There is still some doubt as to the origin of this radiation, the intensity of which increases with height above the earth. It may be, as Prof. C. T. R. Wilson has suggested, that it is of terrestrial rather than of cosmical origin, and may be due to the high velocity electrons and consequent radiation which should be present in strong electrical disturbances like thunderstorms. No doubt the ionization in the upper levels is much increased by the “auroral” rays which extend down to about 100 km. above the earth.