Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business First published 1992 by CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 Reissued 2018 by CRC Press © 1992 by LEWIS PUBLISHERS, INC. CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Jones, Frank E. Evaporation of water : with emphasis on applications and measurements / Frank E. Jones. p. cm. Includes bibliographical references and index. ISBN 0-87371-363-X 1. Evaporation. 2. Evaporation—Measurement. 3. Evapotranspiration—Measurement . I. Title QC304.J66 1991 530.4’27—dc20 91-18818 A Library of Congress record exists under LC control number: 91018819 Publisher’s Note The publisher has gone to great lengths to ensure the quality of this reprint but points out that some imperfections in the original copies may be apparent. Disclaimer The publisher has made every effort to trace copyright holders and welcomes correspondence from those they have been unable to contact. ISBN 13: 978-1-315-89286-3 (hbk) ISBN 13: 978-1-351-07196-3 (ebk) Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com This book is dedicated to my lovely Christian wife, Virginia and to our talented children, Cynthia and Christopher. He causeth the vapours to ascend from the ends of the earth. Psalms 135:7 Preface The loss of water from storage areas such as reservoirs, lakes, rivers, oceans, vegetation, earth, and irrigation conduits is a major concern of hy- drologists and irrigation specialists. This loss, coupled with the relative scar- city of water in some areas, indicates the necessity for understanding the parameters and processes that comprise and contribute to evaporation. This book reviews the literature pertinent to the fundamental processes involved in the evaporation of water. It covers many more practical areas as well. I hope it will be useful to a diverse readership including hydrologists, meteorologists, climatologists, irrigation specialists, civil engineers, chemical engineers, water conservation specialists, hydraulic engineers, agricultural engineers, agronomists, water resources specialists, geophysicists, fluid dy- namicists, environmental engineers, and water storage specialists, as well as farmers and others who store water or use it for irrigation. The writing is intended to be simple and easily understood, and both S1 units and English units are used in order that units not be a barrier for anyone. The intent of the book and many of the subjects covered are quite different from those of Brutsaert's excellent book.* The book begins with an introduction in which the importance of evapo- ration is stressed. The volume of water in oceans, freshwater lakes, saline lakes, inland seas, rivers, soil, and the vadose zone is listed. The annual precipitation on the ocean and land areas of the earth is equal to the annual evaporation from the ocean and land areas, a very interesting and important conservation of water in the hydrologic cycle. The need for adequate knowl- edge of evaporation in the water balance and water management and the need for consistent measurement of evaporation and evapotranspiration are em- phasized. The conservation of water in storage facilities, and attempts to suppress evaporation from them, is mentioned. Agricultural imgation as the largest consumptive user of water in the United States, in which there are 60 million irrigated acres contrasted with 500 million irrigated acres in the rest of the world, is stressed. Loss of water by evaporation from water drops and * Bmtsaert, W. Evaporation into the Atmosphere (Boston, MA: D. Reidel Publishing Co., 1982). attempts to stabilize aqueous fogs and atmospheric mists are mentioned, as is the application of the knowledge of water evaporation to other problems. Following the introduction, there is a detailed treatment of the transport of water across the liquid water-gas (air and water vapor) interface including the following topics: kinetic theory of gases, evaporation and condensation of water, the principle of detailed balancing, absolute reaction rates, the concept of diffusional resistance, heat and mass transfer, flow in a fully developed turbulent boundary layer, evaporation by spurts, and evaporation of water in electric fields. Perhaps incongruously, the preparation of water is included in this chapter. In Chapter 3, the controversial and occasionally misunderstood subject of evaporation and condensation coefficients is presented with many summaries of experimental investigations of these coefficients. The Hertz-Knudsen equa- tion is given in simple forms, along with an example of the calculation of the evaporation coefficient using the equation. A discussion of the maximum rate of evaporation of water attempts to account for confusion in the use of the Hertz-Knudsen equation. The discussion of the evaporation of water drops includes the kinetics of the evaporation of droplets, evaporation from freely falling water drops, and the effects of insoluble films, charged water drops, vertical tunnel studies, and evaporation losses from sprinkler irrigation sys- tems. Surface tension, convection, and interfacial waves are combined in Chapter 5. The subjects covered are surface tension, convection, effects of waves, effects of monomolecular films, the effect of uniform rotation, effects of a progressive wave, liquid flow patterns, heat transfer and thermal structure in a boundary layer, flow patterns in an evaporating liquid layer, wind generated waves, and the effects of waves on evaporation. The measurement of surface temperature (an important quantity in the calculation of evaporation and con- densation coefficients), temperature differences between water surface and the bulk water, temperature gradients, temperature of water in a film-treated reservoir, and water vapor distribution above a water surface are treated in Chapter 6. Similarity, dimensionless groups, and wind tunnel experimentation are covered in a chapter on wind tunnel investigations of evaporation. The use of monomolecular films in attempts to suppress evaporation is treated in detail in Chapter 8 under the following topics: reduction of evaporation rate by monomolecular films, steps in the evaporation process, changes in the gaseous diffusion layer, changes in heat flux and near-surface temperature structure, alteration of surface temperature, heat and mass transfer, increase in tem- perature of water in a reservoir, resistances to evaporation, evaporation rates of film-coated water drops, stabilization of water drops, inhibition of evap- oration from agar gel, effects of monolayers on the rate of evaporation of water and on the solution of oxygen in water, the effects of traces of permeable substances, and the reduction of evaporation from lakes and reservoirs. Equations used to calculate evaporation rate and evapotranspiration are presented in Chapter 9. The subjects covered are the bulk aerodynamic equa- tion, the Penman equation, evapotranspiration determination using the Bowen ratio method, a comparison of equations, eddy correlation, evaporation from a rough surface, calculated evapotranspiration from remotely sensed reflected solar radiation and surface temperatures with ground-station data, evaluation of evaporation using airborne radiometry and ground-based meteorological data, estimation of evaporation using thermal infrared satellite imagery, and evaporation from heated water bodies. Two chapters are devoted to field instrumentation for measuring evaporation and evapotranspiration. In Chapter 10, evaporation pans are treated under the following topics: the Class A pan, the Young screened pan, the Colorado sunken pan, the sunken pan of the Bureau of Plant Industry, the GGI-1000 pan, the 20-m2 basin, the Los Angeles County Flood Control District pans L and G, floating pans, the heat balance of the Class A evaporation pan, si- multaneous recording of pan evaporation and rainfall, differences in evapo- ration pan data, evaporation from non-marine brines, the effect of salinity and ionic composition on evaporation, and pan-evaporation data as a practical tool for estimating potential evapotranspiration. In Chapter 11, lysimetry is treated under the following topics: lysimetry