Basics of Evaporation and Evapotranspiration - University of Arizona Cooperative Extension AZ1194 (PDF 159KB 4 pages)
Crop Evapotranspiration: Guidelines for Computing Crop Water Requirements - The Food and Agriculture Organization (FAO) of the United Nations presents a procedure for calculating reference and crop evapotranspiration from meteorological data and crop coefficients. These guidelines are intended for project managers, consultants, irrigation engineers, hydrologists, agronomists, meteorologists, and students. They can be used for computing crop water requirements for both irrigated and rainfed agriculture, and for computing water consumption by agricultural and natural vegetation.
Evaporation Pan Coefficients - Table of pan coefficients (K pan) for Class A and Sunken Colorado pans for different ground cover and levels of mean relative humidity and 24 hour wind. From the Food and Agriculture Organization (FAO) of the United Nations.
Instructions for the Installation and Operation of Class "A" Evaporation Stations - by Benjamin Clinton Kadel, United States Department of Agriculture, Weather Bureau, Instrument Division, W.B. No 559, Circlular L, issued October 16, 1915. (Digitized by Google Books.)
Introduction to the Hydrosphere: Evaporation and Transpiration - This section from the online textbook Fundamentals of Physical Geography by Dr. Michael Pidwirny, Okanagan University College, Canada, covers evaporation, transpiration, and evapotranspiration.
NWS Observing Handbook No. 2: Cooperative Station Observations - Section 5 provides instructions on installing and maintaining a manual evaporation station. (PDF 1.4MB 94 pages)
NWS Training Module: Evaporation Stations - Describe the station and associated equipment as used by the National Weather Service. Provides descriptions of the required instruments, and details of installation and maintenance procedures.
Siting and Maintance of Weather Stations for Computing Evapotranspiration - University of Arizona Cooperative Extension (PDF 90KB 5 pages)
Use and construction of a lysimeter to measure evapotranspiration - by Donald Perkins
Using Modified Atmometers (ETgage) for Irrigation Management - This guide from the University of Nebraska describes the atmometer (evapotranspiration gage) and explains how it can be used for irrigation scheduling. Examples are provided to show how information collected with an atmometer can be used to estimate crop water use for corn and soybean.