Airborne infrared radiometer investigation of water surface temperature with and without an evaporation-retarding monomolecular layer

Airborne infrared radiometer measurements of water surface temperatures at Lake Hefner, Oklahoma, show an average diurnal variation of about 1°C for late summer conditions. The lake surface, cooled by evaporation, was 0.4° to 0.9°C cooler than the water about 1 cm below the surface. Applications of an evaporation-reducing monomolecular film reversed this gradient. The surface water temperature was 0.3°C warmer under the monomolecular layer than in the surrounding open water.