A solid understanding of psychrometrics, the science that involves properties and processes of moist air, can prevent costly mistakes in the design and operation of commercial, residential and industrial cooling, dehumidification, drying and humidification systems. Understanding Psychrometrics, ISBN 1-931862-14-1, published by ASHRAE, provides a practical desk reference book for air conditioning designers, process engineers and meteorologists and a learning module for students and those new to the field. Experienced practitioners will benefit from the frequently asked questions, altitude effects, fan temperature rise and other chapters.