• • • • • • • • * 



Figure 8 Flight Track, Bermuda to U. S.— 12 March 1966 



EXPERIMENTS 



Infrared Measurements 



General 



The amount of radiation emitted from the sea surface is propor- 

 tional to the fourth power of its absolute temperature. For the usual 

 range of ocean temperatures (275°-305°K) this radiation is in the infra- 

 red portion of the spectrum. Maximum radiation occurs around 10 microns. 



Infrared radiation is strongly absorbed by water vapor in the 

 atmosphere. There are, however, certain zones called "windows" through 

 which infrared radiation is propagated with minimum loss. One such 

 window exists between wavelengths of 8 and Ik microns— the region of 

 the maximum intensity of radiation from the sea. The airborne radiation 

 thermometer measures sea surface temperature by comparing the infrared 

 radiation emitted from the sea in this 8- to 1^- micron region to an 

 internal reference source. 



The infrared scanner does not measure temperature but merely deter- 

 mines relative infrared intensities within an area. The mechanism scans 

 areas on both sides of the flight path. The result is a thermal con- 

 trast image of an area (HRB Singer). 



12 



