Short Period Solar VariationsThe Sun's Short Regular Variation and Its Large Effect on Terrestrial Temperatures by C. G.AbbotReview by: Gustaf StrombergThe Scientific Monthly, Vol. 65, No. 2 (Aug., 1947), p. 176Published by: American Association for the Advancement of ScienceStable URL: http://www.jstor.org/stable/19025 .

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176 TTE SCIENTIFIC MONTHLY

the full and varied life that the author still enjoys.

B1. Y. IORRISON

Bureau of Plant Industry, Soils, and Agricultural Engineering

U. S. D. A.. Beltsville. Md.

SHORT PERIOD SOLAR VARIATIONS

The Sun's Short Regular Variation and Its Large Ef/ect on Terrestrial Temperatures. C. G. Abbot. 33 pp. 30 cents. Smiths. Mis. Coll., Vol. 107, No. 4. Washington. 1947.

A TER his retirement in 1944 as Secre- tary of the Smithsonian Institution,

Dr. C. G. Abbot, now a Research Associate of that Institution, has continued his work of correlating the variations in the solar constant with the temperature variations at the earth's surface. His latest work begins with the followino3 statement:

I propose to show that there is a regular period of 6.6456 days in solar variation, and that terrestrial temperatures respond with changes from 2? to 200 F. in exactly the same average period of recurrence. While the sun's variation appears to be perfectly regular in phase, always recurring on the day pre- dicted, the terrestrial responses come sometimes for a Month or more in succession from I to 3 days early or late. This, which by mechanical analogy we might call backlash, is doubtless the circumstance which hitherto has prevented meteorologists from recog- fizing the nature of this large temperature variation. When examined with the knowledge of the 6.6456 day solar period, the temperature effect is indeed so strikingly obvious, as the reader may see from figures 3 and 5, that no one could doubt that it is both real and a major element in weather. Meteorologically, this regular average periodicity appears to be a new discovery. It is not to be confused with temporary weather periods, ranging from 3 to 7 days in length and changing their phases from time to time, which have been discussed by Clayton [et atl.

In 1936 Dr. Abbot published two papers on the dependence of terrestrial tempera- tures on solar variation. The amplitude of the temperature was about 10TF., and the variation of the solar constant was about 0.7 percent of its value. Meteorologists, physicists, and astronomers have to this day remained skeptical as to whether the Smithsonian observations of the solar con- stant really were accurate enough to es- tablish solar variations from day to day. In his latest study Dr. Abbot has exclu- sively used the accurate determinations of the solar constant made at Montezuma, Chile, from 1924 to 1944. In his previous analysis only the larger variations could be discerned individually, but in this recent study excessive changes were omitted as spurious. The period in the solar variation was determined with high accuracy, but the amplitude was found to be only about 0.13 percent of the solar constant.

The amplitude of solar change is so small, compared to the average amplitude of tem- perature change associated with the 6.6456- day periodicity, that Dr. Abbot is inclined to attribute the terrestrial temperature effects to some indirect action, such as fluctuations in the amount of ozone in the higher atmospheric strata. Since the phases of the temperature recurrence remain almost unchanged in any one month, and the variation of amplitude is not often ex- cessive within that interval, temperature forecasts of the order of a month in advance appear to be feasible with the aid of the cycle newlv discovered by Dr. Abbot. Meteorologists now have a chance of testing the practical value of "Abbot's Cycle."

GUSTAF STROMBERG Pasadena, Calif.

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