scholarly journals The causes of atmospheric inhomogeneities

1963 ◽  
Vol 19 ◽  
pp. 132-143 ◽  
Author(s):  
R. S. Scorer
Keyword(s):  
Thermal Convection ◽  
Pressure Fluctuations ◽  
Temperature Fluctuations ◽  
Stable Layer ◽  
Free Air

There are several different atmospheric causes, of imperfections in the images seen in a telescope. The most serious are due to thermal convection from the ground, or the stirring of a stable layer at the ground by wind : choice of site and observatory design can reduce these effects. In the free air well away from the ground some of the largest inhomogeneities may be due essentially to large gradients of humidity, and certain cloud types indicate the mechanisms by which such inhomogeneities are established. Temperature fluctuations caused by pressure fluctuations in eddies close to the telescope are probably not serious, and can be avoided by observatory design.

scholarly journals Effects of rotation on temperature fluctuations in turbulent thermal convection on a hemisphere

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
T. Meuel ◽  
M. Coudert ◽  
P. Fischer ◽  
C. H. Bruneau ◽  
H. Kellay
Keyword(s):  
Thermal Convection ◽  
Temperature Fluctuations ◽  
Effects Of Rotation

The electron-beam fluorescence technique for measurements in hypersonic turbulent flows

1975 ◽  
Vol 72 (4) ◽  
pp. 695-719 ◽  
Author(s):  
Jerome A. Smith ◽  
James F. Driscoll
Keyword(s):  
Boundary Layer ◽  
Electron Beam ◽  
Turbulent Flows ◽  
Pressure Fluctuations ◽  
Temperature Fluctuations ◽  
Fluorescence Technique ◽  
Adiabatic Wall ◽  
Tunnel Wall ◽  
Wall Boundary Layer ◽  
Temperature And Pressure

The electron-beam fluorescence technique has been employed in measuring simultaneous density and temperature fluctuations in a hypersonic (M ≃ 16), adiabatic wall boundary layer. The paper discusses this technique, as it is applied to the conditions of relatively high density associated with turbulent flows. It presents general considerations concerning the attainable frequency response and spatial resolution of the technique. It describes results from initial measurements in a boundary layer on a wind-tunnel wall. These results show that the r.m.s. of the density, temperature and pressure fluctuations are large, much larger than observed in supersonic boundary layers.

Multi-point local temperature measurements inside the conducting plates in turbulent thermal convection

2007 ◽  
Vol 570 ◽  
pp. 479-489 ◽  
Author(s):  
CHAO SUN ◽  
KE-QING XIA
Keyword(s):  
Thermal Convection ◽  
Large Scale ◽  
Time Derivative ◽  
Temperature Fluctuations ◽  
Local Temperature ◽  
Maximum Temperature ◽  
Convection Cell ◽  
Scaling Properties ◽  
Plume Emission ◽  
Plume Clusters

An experimental study of local temperature statistics in turbulent thermal convection is presented. The emissions of plumes and plume clusters are detected by an array of thermistors embedded in the top and bottom plates of a 1 m diameter convection cell. We found that the product STST′ of the temperature skewness ST and the skewness of the temperature time derivative ST′ from the embedded thermistors may be used as a measure of the intensity of plume emissions and that STST′ exhibits a pattern that corresponds well to the orientation of the large-scale circulation in the convecting flow. This is despite the fact that the temperature distribution across the plates is highly uniform, as indicated by the mean temperature of the embedded thermistors. By comparing the spatial distributions of STST′ and of the RMS temperature σ, we further find that the maximum temperature fluctuations take place in regions dominated by plume mixing instead of regions of plume emission. It is also found that temperature fluctuations inside the conducting plates have the same statistical and scaling properties as those in the cell centre.

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