Chapters 1 and 2 provide a perspective of atmospheric science, both as background for the neophyte and as a means of establishing the boundary conditions for microclimatology. Students, and professionals at all levels, continually find it both useful and intellectually rewarding to view the microsphere as part of the larger system. In this regard, supplementary reading and classroom discussion are encouraged as essential to more comprehensive understanding. Chapters 3 to 7 discuss heat transfer processes and energy budget concepts, limited for the most part to the steady state. Some of the basic physical relationships are reduced to practical approximations to emphasize their immediate relevance in microclimatology. Extensive use is made of line drawings both to illustrate hypothetical steady-state phenomena and to focus attention on the dynamic nature of the system. The traditional system of units is used almost exclusively (metric units, Centigrade scale, heat units in calories); symbols with explanatory notes are listed separately preceding chapter 1, and additional elaboration is provided in the text. Chapters 8 to 10 are oriented toward applications of the principles. Selected Topics (chapter 8) are examples of microclimatological approaches to forestry-related activities and problems associated with wildland management. Microclimate Observation (chapter 9) and Problem Types (chapter 10) are designed for use in conjunction with preceding chapters.