Relations Among Fluctuations of the Cosmic-Ray Ionization, of the Terrestrial Magnetic Field, of the Atmospheric Potential Gradient, and of the Absolute Humidity

In a recent paper the writers reported observations of the cosmic-ray ionization at four-hour intervals during a period of fifteen consecutive days. No regular diurnal variation was observed. The usual dependence of the ionization upon barometric pressure was observed, but no direct dependence upon atmospheric potential gradient, atmospheric temperature or absolute humidity was apparent. Dr. E. O. Hulburt suggested to the writers that there might be some correlation between fluctuations of the cosmic-ray ionization and terrestrial magnetic activity. Defining the cosmic-ray ionization "character" as the product of the average for a particular day by the difference between the maximum and minimum ionization values for that day, the writers found a considerable correspondence between the ionization "character" curve and the curve representing the magnetic character of days during the period of the observations. Further similarities with the corresponding "character" curves for the atmospheric potential gradient and the absolute humidity were brought out. Certain important consequences are pointed out.