The temperature difference of wet and dry bulbs of a psychrometer is independent of the change of air flow velocity if in more than a certain limit of the velocity, which is dependent on the structure of the psychrometer. Described in this paper is a new psychrometer of small air flow velocity limit (ca. 0.6m/s).
In this psychrometer, a thermopile is attached to a thin long rectangular mica plate, one end of which is covered by a piece of wet gauze. The plate is placed in a pipe with reflective inside surface. Radiation shelters are put parallel to this thin plate thermopile.
Air flows from dry end to the wet end of the plate. The temperature difference of the two ends is measured by the thermopile and the air temperature by a thermistor.
