The measurement of temperature within cloudy air is of fundamental importance to atmospheric scientists. Unfortunately, in-cloud air temperature can not be properly measured if the sensor used to measure the temperature becomes wet. Many different housings have been developed for the purpose of shielding temperature sensors from hydrometeors while allowing adequate sampling of ambient air. To date, however, all housings still allow some sensor wetting under various conditions. The extent of this problem has been difficult to ascertain, however, because no standard existed against which immersion sensors could be tested. Recently, a fundamentally different instrument which does not suffer from this wetting problem has been developed. Unfortunately, this instrument, known as a radiometric thermometer, is expensive, large and heavy which makes widespread use in research aircraft unlikely in the near future. The Principal Investigators will use this radiometric thermometer to study the wetting characteristics of the most commonly used immersion probes. New knowledge will be gained on the magnitude of the problem and the conditions under which wetting occurs. This will allow post calibrations to be applied to previously collected data, thus improving its quality. The knowledge gained from this study also will allow the Principal Investigators to pursue developing an improved housing for a light weight and less expensive immersion sensor.
