Horizontal Temperature Gradient at 200 MB and Adjacent Levels

1956 ◽  
Vol 37 (2) ◽  
pp. 47-54
Author(s):  
Adam Kochanski
Keyword(s):  
Temperature Gradient ◽  
Temperature Difference ◽  
Wind Shear ◽  
Extreme Temperature ◽  
Vertical Wind Shear ◽  
Temperature Gradients ◽  
Horizontal Temperature Gradient ◽  
Horizontal Gradients ◽  
Gradient Measurements ◽  
Horizontal Temperature Gradients

Horizontal temperature gradients as large as 7C° per distance of one degree latitude are observed occasionally on 200-mb maps and (with a generally opposite direction) on 500-mb maps. These values are derived from gradient measurements in the vicinity of stations with temperature observations. Aircraft reports yield still higher horizontal gradients: 9C° to 11C° per 1 deg lat. An extreme temperature difference of 13C° over a distance of % deg lat appears feasible, based on extrapolation of differences found over greater distances. The last value is equivalent geostrophically to a vertical wind shear (allegedly observed by aircraft) of 60 kts/1000 ft.

XXV.—The Determination of Temperature Gradients over the Greenland Ice Sheet by Optical Methods

1957 ◽  
Vol 64 (4) ◽  
pp. 381-397
Author(s):  
R. A. Hamilton
Keyword(s):  
Temperature Gradient ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Temperature Gradients ◽  
Lower Atmosphere ◽  
Optical Methods ◽  
Snow Surface ◽  
Vertical Angle ◽  
Gradient Measurements

SynopsisThe temperature gradient in the lower atmosphere can be directly determined by measuring the optical refractive index of the air. This method is suitable for use on the Greenland ice sheet where errors introduced by water vapour are small, and where the strong solar radiation reflected by the snow surface makes it difficult to measure temperature differences over height differences of about I metre.The refraction was measured by observing the apparent vertical angle of each of a set of targets at distances up to 4 km. from a theodolite. The refraction was found to vary linearly with the distance of the target. The true vertical angle to the targets was determined when a second theodolite was available and reciprocal sights could be taken with it from the site of target to the fixed theodolite. The true vertical angle varied with time due to slow descent of the theodolite as the firn slumped; a correction for this was made. The standard error of the temperature gradient measurements was about 1.5 × 10−2 C.° per metre. It is considered that the method could be developed and improved so that over a range of only 100 metres temperature gradients could be measured to an accuracy of about 0·1° C. per metre.

scholarly journals Fluid Dynamics Simulation and Temperature Gradient Validation along a Greenhouse Temperature Gradient

2020 ◽  
Author(s):  
Sung Kyeom Kim ◽  
Hee Ju Lee ◽  
Seung Hwan Wi ◽  
Seong-Won Lee ◽  
ILHWAN Seo
Keyword(s):  
Climate Change ◽  
Fluid Dynamics ◽  
Temperature Gradient ◽  
Temperature Change ◽  
Temperature Difference ◽  
Physiological Response ◽  
Crop Production ◽  
Extreme Weather ◽  
Temperature Gradients ◽  
Response To Temperature

Abstract Background: Climate change is increasing the vulnerability of horticultural crop cultivation and production. It is urgent to study such extreme weather phenomena (heatwave, drought, etc.), and in particular, to evaluate crop productivity according to temperature change. For this purpose, the crop physiological response to temperature change in simulated weather conditions was studied. However, there is a limitation in artificial light wavelength, which requires experiments to be carried out in protected facilities or open fields. In this study, we simulated temperature differences with computational fluid dynamics (CFD) in tunnel-type greenhouses. They can create temperature gradients and improve the accuracy of CFD with vertically and horizontally measured temperature profiles. The growth and physiological response of Kimchi cabbage were examined and validated using a temperature gradient within a semi-closed plastic tunnel.Results: Correlation coefficients of measured heights were: 1.120, 0.597, and 0.459. Root mean square error was below 0.1025, which means the CFD simulation values were highly accurate. The error analysis showed that it was possible to accurately predict temperature gradients change within a semi-closed tunnel-type greenhouse using CFD techniques. CFD results showed an average error of 0.597°C compared to field monitoring results. The maximum temperature difference of GTG was 5.7°C, suggesting a well-controlled set point (6°C difference between outside conditions and inside conditions of GTG). In a cloudy day, the gradient temperature of GTG was well maintained by the set differential temperature (dT), which suggests that the set dT was not precisely and accurately performed in GTG of a sunny day. There was a significant difference in the growth, net photosynthetic rate, transpiration rate, and Ci concentration along with temperature differences in GTG. Conclusions: CFD can simulate temperature gradient distribution in a tunnel-type greenhouse and predict the temperature difference for equipment with different specifications. These facilities can be used in climate change-related studies, such as assessment of crop production area optimization, crop physiological response to temperature, vulnerability assessment of crop production under increasing temperatures, or extreme weather.

scholarly journals Fluid Dynamics Simulation and Temperature Gradient Validation along a Greenhouse Temperature Gradient

2020 ◽  
Author(s):  
Sung Kyeom Kim ◽  
Hee Ju Lee ◽  
Seung Hwan Wi ◽  
Seong-Won Lee ◽  
ILHWAN Seo
Keyword(s):  
Climate Change ◽  
Fluid Dynamics ◽  
Temperature Gradient ◽  
Temperature Change ◽  
Temperature Difference ◽  
Physiological Response ◽  
Crop Production ◽  
Extreme Weather ◽  
Temperature Gradients ◽  
Response To Temperature

Abstract Background: Climate change is increasing the vulnerability of horticultural crop cultivation and production. It is urgent to study such extreme weather phenomena (heatwave, drought, etc.), and in particular, to evaluate crop productivity according to temperature change. For this purpose, the crop physiological response to temperature change in simulated weather conditions was studied. However, there is a limitation in artificial light wavelength, which requires experiments to be carried out in protected facilities or open fields. In this study, we simulated temperature differences with computational fluid dynamics (CFD) in tunnel-type greenhouses. They can create temperature gradients and improve the accuracy of CFD with vertically and horizontally measured temperature profiles. The growth and physiological response of Kimchi cabbage were examined and validated using a temperature gradient within a semi-closed plastic tunnel.Results: Correlation coefficients of measured heights were: 1.120, 0.597, and 0.459. Root mean square error was below 0.1025, which means the CFD simulation values were highly accurate. The error analysis showed that it was possible to accurately predict temperature gradients change within a semi-closed tunnel-type greenhouse using CFD techniques. CFD results showed an average error of 0.597°C compared to field monitoring results. The maximum temperature difference of GTG was 5.7°C, suggesting a well-controlled set point (6°C difference between outside conditions and inside conditions of GTG). In a cloudy day, the gradient temperature of GTG was well maintained by the set differential temperature (dT), which suggests that the set dT was not precisely and accurately performed in GTG of a sunny day. There was a significant difference in the growth, net photosynthetic rate, transpiration rate, and Ci concentration along with temperature differences in GTG.Conclusions: CFD can simulate temperature gradient distribution in a tunnel-type greenhouse and predict the temperature difference for equipment with different specifications. These facilities can be used in climate change-related studies, such as assessment of crop production area optimization, crop physiological response to temperature, vulnerability assessment of crop production under increasing temperatures, or extreme weather.

The Response of a Uniform Horizontal Temperature Gradient to Heating

2007 ◽  
Vol 64 (10) ◽  
pp. 3708-3716 ◽  
Author(s):  
Maarten H. P. Ambaum ◽  
Panos J. Athanasiadis
Keyword(s):  
Temperature Gradient ◽  
Hilbert Transform ◽  
Temperature Anomaly ◽  
Vertical Wind Shear ◽  
Surface Flow ◽  
Time Varying ◽  
Extended Version ◽  
Horizontal Temperature Gradient ◽  
Local Bound ◽  
Temperature Tendency

Abstract The response of a uniform horizontal temperature gradient to prescribed fixed heating is calculated in the context of an extended version of surface quasigeostrophic dynamics. It is found that for zero mean surface flow and weak cross-gradient structure the prescribed heating induces a mean temperature anomaly proportional to the spatial Hilbert transform of the heating. The interior potential vorticity generated by the heating enhances this surface response. The time-varying part is independent of the heating and satisfies the usual linearized surface quasigeostrophic dynamics. It is shown that the surface temperature tendency is a spatial Hilbert transform of the temperature anomaly itself. It then follows that the temperature anomaly is periodically modulated with a frequency proportional to the vertical wind shear. A strong local bound on wave energy is also found. Reanalysis diagnostics are presented that indicate consistency with key findings from this theory.

Thermal Instability in Fluid Layers in the Presence of Horizontal and Vertical Temperature Gradients

1969 ◽  
Vol 36 (1) ◽  
pp. 121-123 ◽  
Author(s):  
T. E. Unny ◽  
P. Niessen
Keyword(s):  
Crystal Growth ◽  
Temperature Gradient ◽  
Thermal Instability ◽  
Temperature Gradients ◽  
Horizontal Temperature Gradient ◽  
Vertical Temperature ◽  
Fluid Layers ◽  
Liquid Material ◽  
Growth Methods ◽  
Special Case

In the horizontal crystal growth methods a horizontal temperature gradient is imposed upon a liquid material. Instances have been recorded when thermal convection has been found to occur in the liquid under these conditions. This report deals with a theoretical investigation on the occurrence of thermal instability in fluid layers subjected to both horizontal and vertical temperature gradients. The solutions obtained include the special case of thermal instability in fluid layers heated from below which has been well treated in the existing literature.

Filament in EUV Lines; Temperature Gradient Measurements

1979 ◽  
Vol 44 ◽  
pp. 136
Author(s):  
Z. Mouradian ◽  
M.J. Martres ◽  
I. Soru-Escaut
Keyword(s):  
Temperature Gradient ◽  
Transition Region ◽  
Transition Zone ◽  
Horizontal Temperature Gradient ◽  
Quiet Sun ◽  
Gradient Measurements

On the EUV spectroheliograms obtained with ATM-Skylab, we studied the temperature gradient of the transition region between a filament and the surrounding corona. For this purpose we established contrast curves defined as the ratio between the intensity of the observed point and the adjacent quiet sun. The filament was scanned in three different positions noted B, R, D. The position of the maximum of the contrast of different lines – C II, C III, O IV, O VI, Mg X – formed in the transition zone (104< T < 106) allows us to deduce the horizontal temperature gradient. The following table gives the results of the gradient measurements in K/km.

Thermosolutal Convection in the Presence of Both Vertical and Horizontal Temperature Gradients

1999 ◽  
Vol 66 (1) ◽  
pp. 181-196
Author(s):  
A. K. Sahai
Keyword(s):  
Temperature Gradient ◽  
Critical Rayleigh Number ◽  
Solute Concentration ◽  
Horizontal Layer ◽  
Stationary Solutions ◽  
Temperature Gradients ◽  
Thermosolutal Convection ◽  
Horizontal Gradient ◽  
Horizontal Temperature Gradient ◽  
Wide Range

The occurrence of stationary and oscillatory solutions in a horizontal layer of fluid in the presence of horizontal and vertical temperature gradients and also in the presence of a vertical solute concentration gradient is investigated. The critical Rayleigh number for oscillatory and stationary solutions is derived numerically for a wide range of values of parameters and it is found that the marginal state is of periodic character in almost all the cases except for very small values of horizontal temperature gradient, solute gradient, and Prandtl number. The effect of horizontal gradient of temperature on the stability of the system is both stabilizing as well as destabilizing. For a large value of horizontal temperature gradient the system first exhibits oscillatory motion and in subsequent time oscillations die down.

scholarly journals Hemisphere-asymmetric tropical cyclones response to anthropogenic aerosol forcing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jian Cao ◽  
Haikun Zhao ◽  
Bin Wang ◽  
Liguang Wu
Keyword(s):  
Tropical Cyclones ◽  
Wind Shear ◽  
Vertical Wind Shear ◽  
Temperature Gradients ◽  
Vertical Wind ◽  
Anthropogenic Aerosol ◽  
Aerosol Forcing ◽  
Aerosol Effect ◽  
Aerosol Emission ◽  
Static Energy

AbstractHow anthropogenic forcing could change tropical cyclones (TCs) is a keen societal concern owing to its significant socio-economic impacts. However, a global picture of the anthropogenic aerosol effect on TCs has not yet emerged. Here we show that anthropogenic aerosol emission can reduce northern hemisphere (NH) TCs but increase southern hemisphere (SH) TCs primarily through altering vertical wind shear and mid-tropospheric upward motion in the TC formation zones. These circulation changes are driven by anthropogenic aerosol-induced NH-cooler-than-SH and NH-increased versus SH-decreased meridional (equator to mid-latitudes) temperature gradients. The cooler NH produces a low-level southward cross-equatorial transport of moist static energy, weakening the NH ascent in the TC formation zones; meanwhile, the increased meridional temperature gradients strengthen vertical wind shear, reducing NH TC genesis. The opposite is true for the SH. The results may help to constrain the models’ uncertainty in the future TC projection. Reduction of anthropogenic aerosol emission may increase the NH TCs threat.

scholarly journals Eddy diffusion of water vapour and heat near the ground

1949 ◽  
Vol 198 (1052) ◽  
pp. 116-140 ◽  
Keyword(s):  
Temperature Gradient ◽  
Water Vapour ◽  
Wind Shear ◽  
Turbulent Transport ◽  
Heat Content ◽  
Vertical Wind Shear ◽  
Ground Surface ◽  
Vertical Wind ◽  
Wave Radiation ◽  
Stable Conditions

An experimental study has been made of the factors involved in the turbulent transport of water vapour and heat in the lowest layer of the atmosphere over well exposed level grassland. Measurements were made over periods of 1 hr. of the water loss from isolated but otherwise naturally exposed sections of the surface layers of the soil and quantitative arguments advanced for adopting them as a reasonable approximation to the true evaporation loss from the ground surface. The incoming and reflected components of solar radiation, the temperature distribution in the soil down to 16 in. and the vertical profiles of temperature, humidity and wind speed in the air up to a height of 2 m. were observed at the same time, and samples taken to provide necessary data on the physical properties of the soil. The net flux of long-wave radiation was computed from the temperature and humidity structure of the atmosphere as given by the present low-level measurements and routine upper-air soundings. The data prescribe the vertical turbulent flux and the vertical gradients of the water vapour and heat content of the air, from which maybe evaluated the vertical components of the eddy diffusivities for water vapour and heat ( K v and K H ) as customarily defined. In the absence of thermal stratification of the surface air layers K v is shown to be identical with the eddy diffusivity for momentum ( K m ) defined by the explicitly established logarithmic law relating the aerodynamic drag and vertical wind shear over a rough surface. The modification of K v by unstable and stable thermal stratifications and the rapid decrease of stability influence as the ground surface is approached are both quantitatively demonstrated, and a unique relation between parameters involving K v , the vertical wind shear and the vertical temperature gradient is indicated. No completely satisfactory a priori explanation can as yet be given for the latter relation, though in unstable conditions K v is found to be identical with K m computed from a recent wind-profile law which does not involve the temperature gradient explicitly and has only been established in functional form. Diroct comparison of K v and K H reveals a reasonable approach to equality in stable conditions but shows that the latter coefficient is systematically and substantially the greater in unstable conditions. The latter feature is qualitatively in keeping with recent trends in the theoretical concepts of turbulent transport. The bearing of the results on the problem of indirectly evaluating natural land evaporation is briefly discussed and attention drawn to the implied superiority of the present ‘ hydro-dynamical’ approach over the classical ‘heat-balance’ method.

Strong temperature gradients and vertical wind shear on MLT region associated to instability source at 23°S

2017 ◽  
Vol 122 (4) ◽  
pp. 4500-4511 ◽  
Author(s):  
V. F. Andrioli ◽  
P. P. Batista ◽  
Jiyao Xu ◽  
Guotao Yang ◽  
Wang Chi ◽  
...  
Keyword(s):  
Wind Shear ◽  
Vertical Wind Shear ◽  
Temperature Gradients ◽  
Vertical Wind ◽  
Mlt Region
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