Some optical properties of turbulence in stratified flow near the ground

Portman, Donald J.; Elder, Floyd C.; Ryznar, Edward; Noble, Vincent E.

doi:10.1029/jz067i008p03223

Cited by 22 publications

(2 citation statements)

References 13 publications

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“…Thus, two ways exist to investigate the refractive index spectrum-with electro-optical instruments or with small, fast-responding meteorological instruments. Portman et al (1962) and Ryznar (1963) did some of the early work on electro-optical propagation over snow and its relation to atmospheric turbulence. Figures 15 and 16 show 0.55-µ m (Φ ") and millimeter ( Φmm) refractive index spectra computed using eq 29 from the temperature and humidity spectra and the t-q cospectra that I have been discussing.…”

Section: Refractive Index Spectramentioning

confidence: 99%

Spectral Measurements in a Disturbed Boundary Layer over Snow

Andreas

1987

J. Atmos. Sci.

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Section: Refractive Index Spectramentioning

confidence: 99%

Spectral Measurements in a Disturbed Boundary Layer over Snow

Andreas

1987

J. Atmos. Sci.

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“…Oberraschend ist jedoch das Fehlen der Abendminima (Abb. 6), die etwa gegen 17,40 MEZ h/itten eintreten mfissen und deren Existenz nach [12,11,15,13,27] [2,20], da naeh den Messungen yon HANSSON U. a. [35], TULENKOWA [36] und MAYER [3] solche Betr/ige auch bei der stellaren Szintillation gemessen wurden.…”

Section: : Verh~iltnis Der Amplitude Gest6rter Minima Zur Amplitude unclassified

Der Tagesgang der Richtungsszintillation einer terrestrischen Lichtquelle. I

Paperlein¹

1968

Arch. Met. Geoph. Biokl. A.

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Moisture transfer in free and forced convection

Crawford

1965

Quart J Royal Meteoro Soc

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MR. J. S. SAWYER : As the author remarks, if equality of K , and Kh exists it is to be attributed to the correlation of humidity and density fluctuations in the turbulent flow. Such a correlation must be affected by the nature ofthe evaporation process at the gr0unde.g. whetherthe evaporating areas are warm or cool relative to areas with less evaporation. Does this imply that the ratio of K , and Kh found in any experiments such as those reported by the author will be rather dependent on the evaporative properties of the underlying vegetation ?DR. H. L. PENMAN : Salutary experience suggests that although the logarithmic profile is true as a long period mean, it is rarely true over short periods. Perhaps unhelpfully, it seems to me that the combined flux ( H + E) is dictated by energy supply, the partition by surface and atmospheric factors, and the gradient of vapour pressure and temperature simply change to cope with the fluxes imposed.Why were the diffusivities for heat and water vapour not compared directly from the Davis measurements instead of comparing the behaviour of E , and H , at two different sites ? MR. J. L. H. SIBBONS (partly communicated) : Dr. Penman has referred to the hypothesis that the available energy is the overriding factor where evaporation is concerned, the profiles and gradients having to adjust themselves to the prevailing flux regime. However, even in the absence of advection or a limiting supply of water the amount of energy available is likely to differ from one type of surface to another. When the boundary is characterized by a very large roughness length the magnitude of K , in the overlying layers is correspondingly high, and the rate at which vapour can be transported away from the surface tends to outstrip that at which water can be converted by the available energy from the liquid to the vapour phase. Adjustment must take the form of a lowering of surface temperature. This acts both to diminish the capacity to remove water vapour by reducing the specific humidity gradient and to augment the energy supply by cutting down the loss of sensible heat from the surface or, should the fall in surface temperature be sufficiently pronounced, causing sensible heat to be received at the boundary, in which case evaporation proceeds at a rate in excess of that maintainable by the net radiation (Sibbons 1958; 1962). The form of the adjustment should be the reverse when the boundary is aerodynamically smooth or of transitional type. Accordingly the potential evaporation and net radiation should be equal at some point on the roughness length scale which remains to be identified and must undergo displacement with changes in thermal stability.The conditions under which the potential evaporation and net radiation will be equal remain a matter for conjecture. Owen and Thomson (1963) have argued on theoretical grounds, and with the support of experimental evidence that some departure from similarity in transfer mechanisms is to be expected above an aerodynamically rough surface. The reason for this ...

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Some optical properties of turbulence in stratified flow near the ground

Cited by 22 publications

References 13 publications

Spectral Measurements in a Disturbed Boundary Layer over Snow

Spectral Measurements in a Disturbed Boundary Layer over Snow

Der Tagesgang der Richtungsszintillation einer terrestrischen Lichtquelle. I

Moisture transfer in free and forced convection

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