238 RADIO WAVE PROPAGATION EXPERIMENTS 
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Ficurs 2. Map of central Florida with locations of weather and radar installations used in Project 3767. 
individual ground-based soundings were likely to be 
too strongly influenced by local topographic effects to 
be completely reliable. Because of clearance require- 
ments, the ground-based soundings were restricted to 
600 ft, although it was determined that 1,000 ft would 
be a much safer limit, with occasional measurements 
up to 3,000 ft considered desirable. Soundings were 
taken before dawn at 1000 Eastern War Time, after 
sunset, and at 2300 EWT to obtain sufficient data on 
the effects of radiation and other meteorological phe- 
nomena. As far as specific sounding procedures are 
concerned, both the small balloons and kites gave 
satisfactory results, although for most of the wind 
speeds encountered in this area the Y-ft kite was too 
small for efficient operation. No limiting surface wind 
speed can be given as a dividing line between kite and 
balloon operation, since it has been found that occa- 
sionally even in surface calms strong velocity gradi- 
ents exist immediately above the surface layer. Al- 
though it is realized that a barrage balloon is not a 
standard item of equipment for sounding measure- 
ments, it is unreservedly recommended and whenever 
available should be used for simplicity and relia- 
bility of sounding procedure. 
The method employed in this project for the 
radar verification of superrefraction was to record 
