2. Convection (In calm seas at the onset of convection of sea surface is covered 

 by thermal spots — the surface expression of convection cells — which are 

 roughly pentagonal or hexagonal in shape. These spots have warm centers 

 and cool edges and may have diameters of the order of one hundred feet.) 



3. Oil films, slicks (The primary effect from oil films seems to be an increase 

 in reflectivity of the surface.) 



4. Wind streaks 



5. Sun glare and glitter (These factors can become very serious at large view- 

 ing angles relative to the vertical.) 



6. Waves (Waves become a significant factor at viewing angles in excess of 30°.) 



7. Whitecaps 



8. Currents in the vicinity of islands, over reefs and along shorelines 



9. Swirling where currents converge or diverge 



10. Oceanic fronts 



11. "Fresh" water from lakes, streams and melted ice "floating" on more dense 

 salt water 



12. Water depth (for shallow secluded waters) 



B. Meteorological conditions that affect IRT readings. 



1. Atmospheric temperature inversion layers 



2. Nascent and evanescent clouds 



3. Concentrations of water vapor in the vicinity of clouds 



4. Fog, clouds (In the absence of sunlight the temperature of the fog or cloud is 

 recorded.) 



5. Reflection of meteorological conditions by the sea surface (The effective 

 temperatures of slicks and oil spots are dependent upon the amount and 

 temperature of cloud cover. Oil spots generally appear cold at night when 

 viewed under clear sky conditions. Under cloudy sky conditions they reflect 

 in part the temperature of the clouds.) 



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