A TECHNIQUE FOR THE DETERMINATION OF WATER IN AIR AT TEMPERATURES BELOW FREEZING

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  • 1 Stanford Research Institute
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Abstract

An investigation of ice fog in Alaska required a technique for the determination of the water content of the atmosphere at temperatures between −20 to −55C. No satisfactory method for direct field measurements at these low temperatures was available.

A field sampling-technique was developed which consisted of extracting the contained water by bubbling the air through absolute methanol, an aliquot of which was then titrated with Karl Fischer reagent. A visual end-point was applicable. The method permitted rapid titration, required simple apparatus, and measured the amount of moisture in the air directly to within 2 per cent of the absolute values.

A method of filtering the air in order to separate water vapor from precipitated water was also developed for sub-freezing temperatures.

Humidity observations were extended to levels above the surface by drawing a known volume of air into the bubbler through polyethylene tubing supported by captive balloons.

Results obtained with these techniques are included in a discussion of humidities determined at Eielson Air Force Base, Alaska, during the winter of 1952–1953.

Abstract

An investigation of ice fog in Alaska required a technique for the determination of the water content of the atmosphere at temperatures between −20 to −55C. No satisfactory method for direct field measurements at these low temperatures was available.

A field sampling-technique was developed which consisted of extracting the contained water by bubbling the air through absolute methanol, an aliquot of which was then titrated with Karl Fischer reagent. A visual end-point was applicable. The method permitted rapid titration, required simple apparatus, and measured the amount of moisture in the air directly to within 2 per cent of the absolute values.

A method of filtering the air in order to separate water vapor from precipitated water was also developed for sub-freezing temperatures.

Humidity observations were extended to levels above the surface by drawing a known volume of air into the bubbler through polyethylene tubing supported by captive balloons.

Results obtained with these techniques are included in a discussion of humidities determined at Eielson Air Force Base, Alaska, during the winter of 1952–1953.

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