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The interpretation of stellar shadow‐bands as a consequence of turbulent mixing
Author(s) -
Townsend A. A.
Publication year - 1965
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49709138702
Subject(s) - turbulence , physics , boundary layer , mixing (physics) , shadow (psychology) , spectral line , geology , atmospheric sciences , optics , mechanics , meteorology , astronomy , psychology , quantum mechanics , psychotherapist
Recently published measurements of shadow‐band patterns produced by star‐light at ground level are analysed using the theory of wave‐propagation in a turbulent medium. The measured spatial and time spectra of the patterns can be described quantitatively by assuming that the optical inhomogeneities are produced by turbulent mixing in the earth's boundary‐layer and in shallow layers at heights around 8 km. Characteristics of the assumed turbulence in the upper air are estimated to be: mean height 8 km, layer depth 90–200 m, r.m.s. velocity fluctuation in wind direction 1·5‐2·0 m sec −1 , r.m.s. temperature fluctuation 0·2°C.