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Natural convection in the earth's boundary layer
Author(s) -
Townsend A. A.
Publication year - 1962
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.49708837505
Subject(s) - richardson number , natural convection , convection , temperature gradient , combined forced and natural convection , boundary layer , mechanics , geology , atmospheric sciences , physics , meteorology , thermodynamics , buoyancy
The relation between the vertical distributions of mean temperature in buoyant convection over a horizontal surface as observed in the atmosphere and in the laboratory is examined. Some measurements by Webb, obtained in conditions of strong instability, are analysed and shown to be consistent with three distinct regions of flow, distinguished by their heat‐transfer characteristics. They are: (i) a region of forced convection with temperature gradient inversely proportional to height (negative Richardson number less than 0·02); (ii) a region of mixed (or free) convection with temperature gradient inversely proportional to the 4/3‐power of the height (negative Richardson number between 0·03 and 1·0) and (iii) a region of natural convection with temperature gradient inversely proportional to the square of the height (negative Richardson number greater than 1·0).Reasons for the existence and properties of the last two regions are discussed briefly.