Light-inadequacy of the ultraviolet theory of ionization in the E-layer

From the reports of the CRPL, average yearly values of h′_E, h′_F1,f °_E and N_F1, for the months of January, March, June, July, September, and December of the years 1944 to 1949 were computed and plotted against the magnetic latitude. Altogether some 25,000 individual records were averaged. Seven curves were plotted. They showed that: (1) all curves are symmetrical with respect to the magnetic equator; (2) the h′_E, h′_F1, f⁰_E and the N_F, curves all swing up and down as the magnetic latitude, north and south, increases; (3) the h′_E is definitely periodic with constant period and constant amplitude; (4) the h′_E curve rises only slightly (on the average) with latitude. These results appear to be inconsistent with the ultraviolet light theory of ionization.