Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
On the Time Lag of the Thermometer
S. Tajima
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1932 Volume 10 Issue 12 Pages 730-736


Recently, Dr. Asahina deviced a new method of measuring the temperature of upper air by a thermometer attached to a pilot-balloon specially constructed for the purpose. The experiments have been made by the present author to estimate the time-lag of that thermometer.
When a thermometer with cylindrical bulb ascends in air with uniform velocity, the steady lag θ is shown to be aproximately as follows:
-where c is the radius of cylinder, a2 the thermal diffusivity, G a constant to be properly determined by taking account the lapse-late and the speed of balloon. Also h is a constant associated with the state of the solid and its surface, assuming Newton's law of cooling,
In this paper, the value of h has been determined experimentally by cooling the thermometer exposed to air-currents of various speeds.
The value of θ is about 0.4_??_5ªC, when the lapse-late is 0.5ªC per 100 meters and the velocity of balloon 100 meters per minute.

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