Abstract
For a noctilucent cloud (NLC) with its typical features the brightness contrast k of such a cloud against the sky is computed as observed from any point within a circle of more than 800 km. This contrast is compared with the contrast threshold ε of the eye. The quotient |k|: ε is a measure of the degree of visibility. Its distribution over the earth’s surface in the vicinity of an NLC at 5 different times during twilight reveals zones of differential visibility (Figs. 4a-e).
DOI: https://doi.org/10.3402/tellusa.v21i3.10100 | Journal eISSN: 3035-9554
Language: English
Page range: 436 - 442
Submitted on: May 6, 1968
Published on: Jan 1, 1969
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services
© 1969 G. Dietze, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.