Formula and notes to estimate evaporation from insolatio

Jensen, M.E.

USDA - ARS - NWISRL

1111i5TER COPY *2ESTIMATING EVAPORATION FROM LNSOLATIONaDiscussion by Marvin E. JensenMARVIN E. JENSEN, 31 M. ASCE.—The writer indicated that the ratioQe/Qs was correlated with plant growth by Jensen and Haise4 and with airtemperature by Stephens and Stewart. 5 The paper by Jensen and Haise4 thatwas cited by the writer presented only part of the results obtained in thestudy completed during the summer of 1962. In their study, Jensen and liaisealso correlated Qe/Qs for crops having a full vegetative canopy and adequatesoil moisture with mean air temperature. The Q e data were obtained fromirrigated crops in several states in the western United States. They obtainedthe relation	t( s- p = 0.014 T - 0.37 	[	 (23)in which (Qe/Qs)p represents the potential ratio, and T is the mean air tem-perature, in degrees Fahrenheit. In Eq. 23 Qs is expressed as the evaporationequivalent of solar radiation assuming a constant heat of vaporization (I gramwater = 590 calories), thus Qe and Qs have the same dimensions. The paperJensen and liaise summarizing the results of the completed study is avail-able. 32If a constant heat of vaporization is assumed, and Qs is the total solarradiation for the month instead of the mean daily value (E is the total for themonth), Eq. 4 becomes	0.013 fa - 0.26 	  (24)which is similar to the potential obtained by Jensen and liaise.17 Carberry, J. J., and Bretton, R. H., 'Axial Dispersion of Mass in Flow ThroughFixed Beds," Journal of the American Institute of Chemical Engineers, Vol. 4, No. 3,September, 1958, pp. 367-375.a September, 1964, by Robert K. Lane (Proc. Paper 4025).31 Research Investigation Leader, Water Mgt., Northwest Branch, Sail and WaterConservation Research Div., Agric., Research Service, U. S. Dept. of Agrlo., Kimberly(Twin Fells), Idaho.EQs

Discussion: Estimating Evaporation from Insolation by R. K. Lane

Northwest Irrigation & Soils Research Laboratory Publications

https://eprints.nwisrl.ars.usda.gov/id/eprint/234/1/24.pdf

Discussion: Estimating Evaporation from Insolation by R. K. Lane

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Northwest Irrigation & Soils Research Laboratory Publications