PREFACE 
Parts A and B of this handbook have been prepared by personnel of the 
U. S. Weather Bureau in collaboration with representatives of the U.S. 
Air Force, U. S. Navy, Environmental Data Service and the Meteoro- 
logical Service of Canada. Every effort has been made to standardize 
procedures where possible in order to provide compatible radiosonde 
observations. Where this is not possible, instructions pertaining to a 
particular service will be identified as follows: WB-Weather Bureau 
N-Navy, AF-Air Force. Part C of the handbook is prepared by the 
individual service and contains instructions which pertain only to that 
service, 
Changes to the handbook and Part C will be issued as page changes ex- 
cept in the case of minor corrections which may be issued as pen and 
ink changes. It is essential that the handbook be kept up to date. When 
changes are received, the effective date, change number, pages affected, 
initials of the person making the change and date the change is entered 
will be recorded on the page entitled ''Record of Changes.,"' 
History of Federal Meteorological Handbook #3 
Instructions for Making Aerological Observations, WB 740, 1921. 
Instructions for Making Aerological Observations, Circular P, 
First Edition, 1930. 
Instructions for Making Aerological Observations by Means of Air- 
planes and Sounding Balloons, Circular P, Second Edition, 1938. 
Instructions for Modulated Audio Frequency Radiosonde Observations, 
Circular P, Third Edition, 1941. Reprinted, June 1942. Fourth 
Edition, August 1943, Fifth Edition, January 1945. 
Manual of Radiosonde Observations, Circular P, Sixth Edition, 
January 1950. 
Manual of Radiosonde Observations, Circular P, Seventh Edition, 
June 1957. 
tS 69 lili FMH#3 
