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Thesis (M.S.)—University of Nebraska—Lincoln, 1961. Department of Agricultural Engineering.


Copyright 1961, the author. Used by permission.


The economic importance of evaporation is very great. Inadequate moisture supply is the factor which most commonly limits crop yields on 150 million acres of cultivated land and 800 million acres of range land in 17 western states. Evaporation, under dry land conditions, accounts for a loss of approximately three-fourths of the precipitation.

The basic physical processes of field evaporation are not well defined, particularly in regard to interaction among themselves. A comprehensive understanding of the factors involved in evaporation is necessary prior to consideration of methods of curtailment of the process.

This thesis describes equipment, procedure, and data designed to provide experimental information pertaining to a better understanding of the fundamental process of evaporation. The theory of diffusion derived from the kinetic theory of gases was tested under controlled conditions.

Equipment and procedures were developed which permitted the study of evaporation of water through a stagnant gas layer into an air stream under controlled conditions of temperature and relative humidity. Eighteen evaporation tests were made. Three tests over a range of nominal relative humidifies from 73 to 23 per cent were made in three replications under each of two container opening conditions. Experimental evaporation rates and rates computed from a diffusion theory were compared.

Advisor: Paul E. Schleusener