Abstract
The noctiiucent cloud display of 10/11th July 1979 was observed from two sites in Scotland: Clinterty near Aberdeen, using a low light level TV camera, and Milngavie near Glasgow, using a photographic camera. Coincident observations of the display were made from 23.55 UT until 00.50 UT. By projecting the image of the noctilucent cloud structure as seen by one camera into the field of view of the other camera, the height of the clouds was found to be 82 ± 1 km. Using this result, the effect of atmospheric screening on the visible border of the noctilucent clouds was determined. Taking account of the refraction on the solar grazing rays illuminating the clouds at the visible border and the finite angular diameter of the sun's disc, the altitude of the screening layer was determined to be 7 ± 1 km. Thus, on this occasion, the screening effect of the atmosphere was confined to the troposphere and was probably caused by atmospheric haze and/or tropospheric cloud. This result contrasts markedly with the high values of screening height, ~ 30 km, deduced from measurements made earlier this century, also using the visible boundary of the clouds. The analysis presented herein indicates that these large values were probably in error, due to the poor dynamic range of the photographic films employed.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
