Ionosphere Studies during Partial Solar Eclipse of February 3, 1935

Virtual height and critical frequency measurements of the several regions of the ionosphere were made during the day of the solar eclipse of February 3, 1935, and during several days before and after the eclipse day. The eclipse was found to produce a decrease of the critical frequency of each region. The decrease of critical frequency was approximately in time phase with the eclipse, thus indicating an ionizing agency (probably ultraviolet light), originating in the sun and propagated at approximately the velocity of light. The decrease of equivalent electron density in each region during the eclipse was compared with the decrease of the exposed area of sun's disk, and found to indicate that the ionization of the normal E region was diminished when the ionizing agency was decreased, by recombination of plus and minus charges, while the ionization of the F
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region and a high stratum of the E was diminished by a process of attachment of electrons to neutral particles.