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- Author or Editor: C. J. Brasefield x
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Abstract
Measurements have been made of atmospheric humidity to altitudes as high as 35 kilometers by means of a hygristor — a humidity-sensitive radiosonde accessory which is essentially a miniature version of the Foxboro Dewcel. The hygristor indicates ambient dewpoint so long as the relative humidity is above a threshold which is roughly 15 per cent. When the relative humidity is below the threshold value, the hygristor indicates the upper limit of possible dewpoint values. Since the relative humidity in the stratosphere was usually very low, most of the humidity data obtained with the hygristor above the tropopause are in the latter category. However, on several occasions when precise values of dewpoint were obtained in the stratosphere, it was found that the dewpoint increased above the tropopause and was even higher than the temperature of the tropopause at altitudes near 20 kilometers.
Abstract
Measurements have been made of atmospheric humidity to altitudes as high as 35 kilometers by means of a hygristor — a humidity-sensitive radiosonde accessory which is essentially a miniature version of the Foxboro Dewcel. The hygristor indicates ambient dewpoint so long as the relative humidity is above a threshold which is roughly 15 per cent. When the relative humidity is below the threshold value, the hygristor indicates the upper limit of possible dewpoint values. Since the relative humidity in the stratosphere was usually very low, most of the humidity data obtained with the hygristor above the tropopause are in the latter category. However, on several occasions when precise values of dewpoint were obtained in the stratosphere, it was found that the dewpoint increased above the tropopause and was even higher than the temperature of the tropopause at altitudes near 20 kilometers.
Abstract
About twenty radiosonde flights to altitudes above 100,000 ft have been made from Belmar, New Jersey (latitude 40.2°N) during the period July 1948 to April 1949, using a balloon whose nominal weight was 10,000 grams. The radiosonde and associated equipment were specially designed to accurately measure pressure, temperature and winds to an altitude of 150,000 ft. It was found that the mean daytime temperature of the stratosphere is about −60C from 50,000 ft to 60,000 ft, above which the mean temperature rises at a rate of about 0.5C per 1000 ft to a temperature of about −30C at 120,000 ft. No abnormally high temperatures at high altitudes resulting, for example, from a solar flare, were detected in any of these flights.
It was found that the winds below 60,000 ft were predominantly westerly, with maximum speed at an altitude of about 40,000 ft. Between 60,000 ft and 120,000 ft, the winds were easterly during the summer and westerly during the winter. The pronounced easterly flow commenced about three weeks after the vernal equinox and ceased about three weeks before the autumnal equinox. Usually the wind speed was still increasing at the bursting altitude of the balloon. These results are consistent with the existence of a stratospheric circumpolar vortex which is cyclonic in winter, anticyclonic in summer. The fragmentary wind data obtained from these flights at high altitudes suggest the possible existence of a stratospheric jet stream in middle latitudes. The significance of such a jet stream, if confirmed, is discussed.
Abstract
About twenty radiosonde flights to altitudes above 100,000 ft have been made from Belmar, New Jersey (latitude 40.2°N) during the period July 1948 to April 1949, using a balloon whose nominal weight was 10,000 grams. The radiosonde and associated equipment were specially designed to accurately measure pressure, temperature and winds to an altitude of 150,000 ft. It was found that the mean daytime temperature of the stratosphere is about −60C from 50,000 ft to 60,000 ft, above which the mean temperature rises at a rate of about 0.5C per 1000 ft to a temperature of about −30C at 120,000 ft. No abnormally high temperatures at high altitudes resulting, for example, from a solar flare, were detected in any of these flights.
It was found that the winds below 60,000 ft were predominantly westerly, with maximum speed at an altitude of about 40,000 ft. Between 60,000 ft and 120,000 ft, the winds were easterly during the summer and westerly during the winter. The pronounced easterly flow commenced about three weeks after the vernal equinox and ceased about three weeks before the autumnal equinox. Usually the wind speed was still increasing at the bursting altitude of the balloon. These results are consistent with the existence of a stratospheric circumpolar vortex which is cyclonic in winter, anticyclonic in summer. The fragmentary wind data obtained from these flights at high altitudes suggest the possible existence of a stratospheric jet stream in middle latitudes. The significance of such a jet stream, if confirmed, is discussed.
Abstract
Air temperatures to altitudes as high as 100,000 feet have been measured with radiosondes carrying a temperature element which was exposed directly to solar radiation. The temperature element was coated with a special white paint which reflected more than 90 per cent of the solar radiation. Air temperatures measured with the white element should not be in error by more than 0.5C except at the highest altitudes. Air temperatures measured with radiosondes using an air duct for radiation shield were higher than temperatures obtained with the white element by 3–6C at 50,000 feet, by 5–10C at 75,000 feet and by as much as 20C at 100,000 feet.
The results of a limited number of flights indicate that to altitudes of 100,000 feet, the heat wake of a balloon does not extend as far as 25 feet below the balloon.
Abstract
Air temperatures to altitudes as high as 100,000 feet have been measured with radiosondes carrying a temperature element which was exposed directly to solar radiation. The temperature element was coated with a special white paint which reflected more than 90 per cent of the solar radiation. Air temperatures measured with the white element should not be in error by more than 0.5C except at the highest altitudes. Air temperatures measured with radiosondes using an air duct for radiation shield were higher than temperatures obtained with the white element by 3–6C at 50,000 feet, by 5–10C at 75,000 feet and by as much as 20C at 100,000 feet.
The results of a limited number of flights indicate that to altitudes of 100,000 feet, the heat wake of a balloon does not extend as far as 25 feet below the balloon.
