Abstract
E. V. APPLETON illustrates the characteristic variation of the ionospheric F2 region ionization throughout the year by curves of critical frequency for stations of similar latitude in both hemispheres. The curves are adjusted to relate to constant solar activity. They show fairly detailed correspondence between ionizing radiation and solar activity.
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Points from Foregoing Letters. Nature 144, 159 (1939). https://doi.org/10.1038/144159a0
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DOI: https://doi.org/10.1038/144159a0