A polyethylene shielded globe thermometer

The construction and use of an improved globe thermometer for the measurement of mean radiant temperature (MRT) is described. The device consists of a 50 mm hollow copper sphere in the center of a 100 mm diameter polyethylene envelope. The figure of merit of the device is about 0.75 in still air falling to 0.7 in an air speed of 0.5 m/s. The corresponding figures for the standard globe thus has a higher sensitivity to thermal radiation than the conventional globe, coupled with lower sensitivity to air movement. Where an index of warmth is required, rather than a measure of MRT, it is shown that the warmth of an environment, described by the subjective temperature, may be obtained from the temperature of an unshielded 25 mm globe thermometer and the air speed.