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Voiv. XVIII Washington, D. C, February i6, 1920 No. 10 



DETERMINATION OF NORMAL TEMPERATURES BY 

 MEANS OF THE EQUATION OF THE SEASONAL TEM- 

 PERATURE VARIATION AND A MODIFIED THERMO- 

 GRAPH RECORD 



By F. L. West, Physicist, and N. E. EdlefsEN and S. Ewing,^ Assistant 

 Physicists, Utah Agricult2iral Experiment Station 



In the fall of 191 8 Logan, Utah, was paving some of its streets. Be- 

 cause of the labor shortage, the work had been delayed and it was feared 

 that freezing weather would set in before the work could be completed. 

 The city engineer asked the writers what temperature Logan would be 

 likely to experience during the third week of November between 4 and 

 6 p. m. They could not tell him. 



In attempting to answer this question the writers were attracted to a 

 study of seasonal temperature change and also to the change in temper- 

 ature as the day advances. These temperature changes occur rather 

 gradually and regularly. It becomes slowly warmer as the day advances; 

 and after the setting of the sun the air cools, until just before sunrise, 

 when it begins to warm again. This is repeated each day. The mean 

 daily temperature gradually rises as the summer approaches, reaches a 

 maximum, begins to fall, and reaches a minimum in the winter. The 

 writers undertook to determine, from the temperature observations of 

 the Weather Bureau, the law connecting the temperature and the time, 

 for the purpose of determining the probable temperature at a particular 

 place for a particular day and a certain hour of that day. 



LITERATURE 



Lambert, Weilenmann, Maurer, Lamont, Trabert, and Angot worked 

 on the problem of the diurnal change in temperature in an attempt to 

 give a mathematical expression for the temperature change in which the 

 constants of the equation had a physical significance.^ The upper part, 



1 The authors wish to thank Dr. Willard Gardner, Associate Physicist at the Utah Agricultural College, 

 for helpful suggestions on this problem. 



2 PERNTER, J. M. PRESENT STATUS OF OUR KNOWLEDGE OP THE CAUSES OF THE DIURNAL CHANGES IN 

 TEMPERATURE, PRESSUREi AND WIND. In Mo. Weather Rev., v. 42, no. 12, p. 655-663. 1914. Notes and 

 references, p. 662-665. 



Discusses in detail articles by Lambert, Weilenmann, Maurer, Lamont, Trabert, and Angot. The orig- 

 inal of these articles not available to the author of this paper. 



Journal of Agricultural Research, Vol. XVIII, No. lo 



Washington, D. C. Feb. 16, 1920 



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