Annals of the Astrophysical Observatory of the Smithsonian Institution (1900)
Washington : Government printing office · leaf 220
nspot numbers rise from zero to about 50 or 60, and then gradually to decrease. Our present study of periodicities in solar variation gives no indication of an 11-year period, as will be seen from curve C of figure 14. We thought, however, that while the amplitude of this period appears to have… … Fig. 18. — Sunspots and solar variation. values of the solar constant corresponding to the sunspot numbers indicated as ab¬ scissae. Each point plotted is the mean of the number of days stated alongside. The days are all of high grade, and are selected throughout the interval 1920 to 1939. The…
Infrared spectra · Solar radiation
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