Since its first appearance in 1941, this book has remained, through various editions and reprintings, the standard, indeed the only modern work in English in its field. This third edition, completely reset, includes descriptions of the newer devices which have come into use in upper-atmosphere sounding, electronic techniques for wind finding, thunderstorm location, and through the renewed interest in meterorological observations from aircraft. A number of new illustrations have been added. The authors have followed the pattern of the earlier editions in presenting examples found in regular weather service. Some attention has been given, however, to new techniques which, though not widely in use at the present time, show such promise as to deserve the studen'ts attention. A general treatment of the application of radar, radio direction finders, and radiosoundes to meteorology has been included. Of the previous edition the bulletin of the American Meteorological Society said: "This is the first general textbook on the subject in English for more than half a century .... While the book is indispensable for reference for the practising meterorologist, the needs of the student are met by an adequate presentation of theoretical topics."