Anyone who merely turns the pages of this new edition will find that 48
percent of the fig- ures are familiar to him from the third edition. But
whoever reads it will discover that no three consecutive pages of text
have been transferred unaltered. The enormous development that has taken
place since 1950, particularly the surprising extension in the practical
applica- tions of micrometeorology, have made it necessary to rewrite
the book. In producing this work, I had in mind two aims which were
linked more closely to each other than I had at first dared to hope. The
new edition was to be a clear and vivid textbook for those who were just
taking up the study of microclimatology, and at the same time a ref-
erence work for those already familiar with the subject. For the fIrst
task, I had in mind the students who would recoil with horror at the
insurmountable barrier of an apparently unlim- ited and ever-increasing
pile of literature and thus were in need of assistance. In addition, I
was thinking of colleagues working in related sciences, who have no time
to study our liter- ature.