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Some observations of air flow over the sea
Author(s) -
Hay J. S.
Publication year - 1955
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.49708134902
Subject(s) - wind speed , fetch , roughness length , wind gradient , environmental science , wind profile power law , meteorology , wind direction , atmospheric sciences , log wind profile , inversion (geology) , surface roughness , flow (mathematics) , thermal wind , mechanics , geology , physics , oceanography , geomorphology , structural basin , quantum mechanics
Wind speeds were measured over the sea at five heights up to 8 m. Though the fetch was limited, the wind profiles obtained are considered representative of flow over the sea. The wind speed varies logarithmically with height when the temperature gradient is small. Assuming that laboratory laws of flow are applicable, values of the roughness parameter z 0 are deduced. It is found that z 0 increases from about 0·02 cm in a wind of 5 m/sec to 0·25 cm at 9 m/sec. The relationship between wind speed and z 0 however is not unique for the state of the surface is determined by other factors beside wind speed. In inversion conditions the wind‐speed distribution departs from the logarithmic form a few metres above the surface. The results obtained are compared with those of some other workers. Bi‐directional vanes were used to obtain gustiness measurements at the site. While the vertical gustiness is found to be of similar magnitude to that over land surfaces of comparable roughness, the cross‐wind gustiness appears to be greater over the sea.