THEORETICAL MODELING OF TEMPERATURE PULSATIONS IN PLANT LEAF WHICH ARE CAUSED BY LEAF SWING WITH RESPECT TO THE SUN / LOKALIŲ AUGALO TEMPERATŪROS PULSACIJŲ, KURIAS SUKELIA LAPO SVYRAVIMAI SAULĖS ATŽVILGIU, TEORINIS MODELIAVIMAS / ТЕОРЕТИЧЕСКОЕ МОДЕЛИРОВАНИЕ ЛОКАЛЬНЫХ ПУЛЬСАЦИЙ ТЕМПЕРАТУРЫ,ВЫЗЫВАЕМЫХ КОЛЕБАНИЕМ ЛИСТ AРАСТЕНИЯО ТНОСИТЕЛЬНО CОЛНЦА

2011 ◽  
Vol 19 (3) ◽  
pp. 251-259
Author(s):  
Algimantas Povilas Sirvydas ◽  
Vidmantas Kucinskas ◽  
Paulius Kerpauskas ◽  
Juratė Nadzeikienė
Keyword(s):  
Temperature Gradient ◽  
Temperature Change ◽  
Position Angle ◽  
Leaf Temperature ◽  
Heat Fluxes ◽  
Leaf Thickness ◽  
The Sun ◽  
Leaf Position ◽  
Plant Leaf ◽  
Temperature Pulsations

The plant leaf temperature is a result of biological processes occurring in an organ of the plant and its energy exchange with the environment. The plant leaf temperature always differs from the ambient temperature except for the moments of transition from a positive to a negative (or vice versa) temperature gradient. It is determined that the plant leaf temperature continuously changes during the sunny time of the day. Temperature pulsations emerge in plant tissues when the leaf naturally changes its position with respect to the Sun (e.g. impacted by the wind) during the sunny period of the day. When a leaf position changes with respect to the source of radiation, a temperature change in the plant leaf also depends on local plant leaf thickness δ, leaf position angle β, leaf oscillation frequency ƒ and a temperature difference between the leaf surface and the atmosphere. When changing its position with respect to the Sun during the sunny period of the day the plant leaf plate becomes a temperature mosaic. Changing the leaf tillt angle from 30° to 60° depending on leaf thickness δ, it is estimated by mathematical modeling that during 6 s the temperature change in the plant leaf reaches 0,03-0,29° C (when β=30°) and 0,11-1,04°C (when β=60°) respectively. Temperature pulsations in the plant leaf entail local temperature gradients in the leaf plate as well as changes in the local balance of plant leaf energies. The anatomic framework of the plant leaf predetermines different local impulses of temperature changes in the plant leaf. The emerged temperature gradient generates heat fluxes in the plant leaf plate. Santrauka Augalo organo temperatūra yra augalo organe vykstančių biologinių procesų ir jo energinės apykaitos su aplinka rezultatas. Augalo lapo temperatūra, išskyrus perėjimo momentus iš teigiamo į neigiamą (arba atvirkščiai) temperatūros gradientą, visuomet skiriasi nuo aplinkos temperatūros. Nustatyta, kad saulėtu paros metu augalo lapo temperatūra nuolat kinta. Saulėtu paros metu natūraliai keičiantis augalo lapo padėčiai Saulės atžvilgiu (pvz., dėl vėjo poveikio) lapo audiniuose kyla temperatūros pulsacijos. Temperatūros pokytis augalo lape, kintant lapo padėčiai spinduliavimo Šaltinio atžvilgiu, priklauso ir nuo lokalaus augalo lapo storio δ, lapo padėties kampo β, lapo svyravimo dažnio ƒ ir temperatūrų skirtumo tarp lapo paviršiaus ir aplinkos. Augalo lapo plokštelė, saulėtu paros metu keisdama padėtį Saulės atžvilgiu, tampa temperatūrine mozaika. Kintant lapo posvyrio kampui nuo 30° iki 60°, matematiškai modeliuojant nustatyta, per 6 s temperatūros pokytis augalo lape priklausomai nuo lapo storio δ (0,11 mm) atitinkamai siekia 0,03-0,29° C (kai β=30°) ir 0,11-1,04° C (kai β=60°). Dėl temperatūros pulsacijų augalo lape susidaro lokalieji temperatūros gradientai lapo plokštelėje, atsiranda pokyčių lokaliame augalo lapo energijų balanse. Dėl augalo lapo anatominės sandaros augalo lape susidaro lokalūs temperatuūros pokyčio impulsai. temperatūros gradientas augalo lapo plokštelėje sukuria šilumos srautus. Резюме Температура органа растения является результатом биологических процессов в нем и его энергетического обменас окружающей средой. Температура листа растения, за исключением моментов перехода от положительного котрицательному (или наоборот) градиенту температуры, всегда отличается от температуры окружающей среды.Установлено, что в солнечные часы дня при натуральном изменении положения листа по отношению к Солнцутемпература листа постоянно меняется. В солнечные часы дня при натуральном изменении положения листаотносительно Солнца (например, под влиянием ветра) в тканях листа возникают температурные пульсации.Температурные изменения в листе растения зависят от локальной толщины листа δ, угла положения листа β,частоты колебаний листа f и разницы между температурой листа и окружающей среды. В солнечные часы дняпластинка листа растения под влиянием ветра меняет положение относительно Солнца и становитсяпульсирующей температурной мозаикой. Математическим моделированием установлено, что изменение угла положения листа β от 30° до 60° в зависимости от толщины листа δ (0,1–1 мм) в течение 6 с вызывает температурные изменения соответственно 0,03–0,29 °C (при β = 30°) и 0,11–1,04°C (при β = 60°). Пульсации температуры влисте растения вызывают локальные градиенты температуры, а также изменения в локальном энергетическомбалансе листа растения. Анатомическая структура листа растения является причиной, вызывающей локальныеизменения температуры, что создает тепловые потоки в пластинке листа растения под влиянием температурногоградиента.

scholarly journals SOLAR RADIATION ENERGY PULSATIONS IN A PLANT LEAF

2010 ◽  
Vol 18 (3) ◽  
pp. 188-195 ◽  
Author(s):  
Algimantas Sirvydas ◽  
Vidmantas Kučinskas ◽  
Paulius Kerpauskas ◽  
Jūratė Nadzeikienė ◽  
Albinas Kusta
Keyword(s):  
Solar Radiation ◽  
Radiant Energy ◽  
Radiation Energy ◽  
The Sun ◽  
Plant Leaves ◽  
Plant Leaf ◽  
Balance Of Plant ◽  
Plant Uses ◽  
Energy Accounting ◽  
Temperature Pulsations

Solar radiation energy is used by vegetation, which predetermines the existence of biosphere. The plant uses 1–2% of the absorbed radiant energy for photosynthesis. All the remaining share of the absorbed energy, accounting for 99–98%, converts into thermal energy in the plant leaf. At the lowest wind under natural surrounding air conditions, plant leaves change their position with respect to the Sun. An oscillating plant leaf receives a variable amount of solar radiation energy, which causes changes in the balance of plant leaf energies and a changing emission of heat in the leaf. The analysis of solar radiation energy pulsations in the plant leaf shows that when the leaf is in the edge positions of angles 10°, 20° and 30° with respect to the Sun, 1.5%; 6% and 13% less of radiation energy reach the leaf, respectively. During periodic motion, when the amplitude of leaf oscillation is no bigger than 10°, the plant surface receives up to 1.6% less of solar radiation energy within a certain period of time, and when the amplitude of oscillation reaches 30° up to 14% less of solar radiation energy reach the leaf surface. The total amount of radiant energy received during pulsations of solar radiation energy is not dependent on the frequency of oscillation in the same interval of time. Temperature pulsations occur in the leaf due to solar radiation energy pulsations when the plant leaf naturally changes its position with respect to the Sun. Santrauka Saules spinduliuotes energija būtina augalijai, kuri lemia biosferos egzistavima. Augalas 1–2 % absorbuotos spinduliuotes energijos sunaudoja fotosintezei, o 99–98 % absorbuotos energijos augalo lape virsta šilumine energija. Natūraliomis aplinkos salygomis esant mažiausiam vejui augalo lapu padetis Saules atžvilgiu keičiasi. Taigi augalo svyruojančio lapo gaunamas Saules spinduliuotes energijos kiekis yra kintamas, tai sukelia pokyčius augalo lapo energiju balanse ir kintama šilumos išsiskyrima lape. Analizuojant Saules spinduliuotes energijos pulsacijas augalo lape, nustatyta, kad, lapui esant kraštinese 10°, 20° ir 30° kampu padetyse Saules atžvilgiu, i ji atitinkamai patenka 1,5 %; 6 % ir 13 % mažiau spinduliuotes energijos. Augalo lapui periodiškai svyruojant, kai svyravimo amplitude yra iki 10°, per tam tikra laika i lapo paviršiu patenka iki 1,6 % mažiau Saules spinduliuotes energijos, o kai svyravimo amplitu‐de siekia iki 30°, – iki 14 % mažiau. Saules spinduliuotes energijos pulsaciju metu gautas bendras spinduliuotes energijos kiekis nepriklauso nuo to paties laiko intervalo svyravimo dažnio. Del Saules spinduliuotes energijos pulsaciju, natūraliai keičiantis augalo lapo padečiai Saules atžvilgiu, lape kyla temperatūros pulsacijos. Резюме Растения потребляют солнечную лучевую энергию, которая является основой существования биосферы. 1–2% абсорбированной лучевой энергии они используют на фотосинтез. В натуральных условиях при малейшем дуновении ветра листья растений меняют свое положение относительно Солнца. Колеблющийся лист получает переменное количество лучевой энергии, которое вызывает изменения в энергетическом балансе листа растения, что сказывается на переменном выделении тепла в листе. Анализируя пульсации солнечной лучевой энергии в листе растения, установлено, что при крайних положениях листа относительно Солнца на 10, 20 и 30 градусов на лист попадает соответственно на 1,5%, 6% и 13% меньше лучевой энергии. При периодическом колебании листа, когда амплитуда его колебания составляет 10 градусов, за известный промежуток времени солнечная лучевая энергия, попадающая на поверхность листа, уменьшается до 1,6%, а при амплитуде колебания до 30 градусов соответственно количество лучевой энергии на поверхности листа растения уменьшается до 14%. Установлено, что суммарное количество солнечной лучевой энергии во время пульсации не зависит от частоты колебания листа за одинаковый промежуток времени. Пульсации солнечной лучевой энергии при изменении положения листа растения относительно Солнца вызывают температурные пульсации в листе.

scholarly journals Reexamining the Gradient and Countergradient Representation of the Local and Nonlocal Heat Fluxes in the Convective Boundary Layer

2018 ◽  
Vol 75 (7) ◽  
pp. 2317-2336 ◽  
Author(s):  
Bowen Zhou ◽  
Shiwei Sun ◽  
Kai Yao ◽  
Kefeng Zhu
Keyword(s):  
Boundary Layer ◽  
Temperature Gradient ◽  
Mixed Layer ◽  
Convective Boundary Layer ◽  
Correction Term ◽  
Potential Temperature ◽  
Heat Fluxes ◽  
Gradient Term ◽  
Convective Boundary ◽  
Upper Mixed Layer

Abstract Turbulent mixing in the daytime convective boundary layer (CBL) is carried out by organized nonlocal updrafts and smaller local eddies. In the upper mixed layer of the CBL, heat fluxes associated with nonlocal updrafts are directed up the local potential temperature gradient. To reproduce such countergradient behavior in parameterizations, a class of planetary boundary layer schemes adopts a countergradient correction term in addition to the classic downgradient eddy-diffusion term. Such schemes are popular because of their simple formulation and effective performance. This study reexamines those schemes to investigate the physical representations of the gradient and countergradient (GCG) terms, and to rebut the often-implied association of the GCG terms with heat fluxes due to local and nonlocal (LNL) eddies. To do so, large-eddy simulations (LESs) of six idealized CBL cases are performed. The GCG fluxes are computed a priori with horizontally averaged LES data, while the LNL fluxes are diagnosed through conditional sampling and Fourier decomposition of the LES flow field. It is found that in the upper mixed layer, the gradient term predicts downward fluxes in the presence of positive mean potential temperature gradient but is compensated by the upward countergradient correction flux, which is larger than the total heat flux. However, neither downward local fluxes nor larger-than-total nonlocal fluxes are diagnosed from LES. The difference reflects reduced turbulence efficiency for GCG fluxes and, in terms of physics, conceptual deficiencies in the GCG representation of CBL heat fluxes.

scholarly journals The Relationship between Land–Ocean Surface Temperature Contrast and Radiative Forcing

2011 ◽  
Vol 24 (13) ◽  
pp. 3239-3256 ◽  
Author(s):  
F. Hugo Lambert ◽  
Mark J. Webb ◽  
Manoj M. Joshi
Keyword(s):  
Surface Temperature ◽  
Heat Transport ◽  
Temperature Change ◽  
Land Surface ◽  
Radiative Forcing ◽  
Co2 Concentration ◽  
Ocean Surface ◽  
Heat Fluxes ◽  
Balance Model ◽  
Surface Temperature Change

Abstract Previous work has demonstrated that observed and modeled climates show a near-time-invariant ratio of mean land to mean ocean surface temperature change under transient and equilibrium global warming. This study confirms this in a range of atmospheric models coupled to perturbed sea surface temperatures (SSTs), slab (thermodynamics only) oceans, and a fully coupled ocean. Away from equilibrium, it is found that the atmospheric processes that maintain the ratio cause a land-to-ocean heat transport anomaly that can be approximated using a two-box energy balance model. When climate is forced by increasing atmospheric CO2 concentration, the heat transport anomaly moves heat from land to ocean, constraining the land to warm in step with the ocean surface, despite the small heat capacity of the land. The heat transport anomaly is strongly related to the top-of-atmosphere radiative flux imbalance, and hence it tends to a small value as equilibrium is approached. In contrast, when climate is forced by prescribing changes in SSTs, the heat transport anomaly replaces “missing” radiative forcing over land by moving heat from ocean to land, warming the land surface. The heat transport anomaly remains substantial in steady state. These results are consistent with earlier studies that found that both land and ocean surface temperature changes may be approximated as local responses to global mean radiative forcing. The modeled heat transport anomaly has large impacts on surface heat fluxes but small impacts on precipitation, circulation, and cloud radiative forcing compared with the impacts of surface temperature change. No substantial nonlinearities are found in these atmospheric variables when the effects of forcing and surface temperature change are added.

scholarly journals The isothermal layer of the atmosphere and atmospheric radiation

1909 ◽  
Vol 82 (551) ◽  
pp. 43-70 ◽  
Keyword(s):  
High Pressure ◽  
Temperature Gradient ◽  
Temperature Change ◽  
Atmospheric Temperature ◽  
Atmospheric Radiation ◽  
Average Height ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Temperature Changes ◽  
Isothermal Layer

The investigation of the upper air by means of balloons carrying self-recording instruments, which have furnished values for the atmospheric temperature up to heights between 15 and 20 kilometres, has revealed the existence of an abnormal change in the vertical temperature gradient. After a fairly uniform fall, with increasing altitude, of about 6° C. per kilometre, a height is reached above which the temperature changes very little, sometimes increasing, sometimes diminishing slowly. The phenomenon was first noticed by M. Teisserenc de Bort in a communication to the Société de Physique in June, 1899. He improved his apparatus and made further investigations, in many cases sending up the balloons by night to eliminate any possible insolation effects. He found the average height, at which the change began, to be about 11 kilometres. He discovered also that the height was greater near the centre of high pressure areas than in low pressure areas, the average heights for the two cases being 12-5 and 10 kilometres respectively. More recently he found that the height increased with approach towards the equator and that near the equator, ballons-sondes , ascending to 15 kilometres, had failed to reach this layer if it existed there. He proposed to call this layer, in which little temperature change occurred, the “Isothermal Layer of the Atmosphere,” and the name has been generally accepted.

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 Optical polarimetry and photometry of young sun-like star LO Peg

2010 ◽  
Vol 6 (S273) ◽  
pp. 455-459
Author(s):  
J. C. Pandey ◽  
B. J. Medhi ◽  
R. Sagar
Keyword(s):  
Radiation Field ◽  
Position Angle ◽  
Degree Of Polarization ◽  
Circumstellar Envelope ◽  
The Sun ◽  
Photometric Study ◽  
V Band ◽  
Stellar Radiation ◽  
Photometric Observations

AbstractWe have carried out the B,V and R-band polarimetric and V-band photometric study of the star LO Peg. Our analysis reveal that LO Peg is highly polarized among the sun-like stars. The degree of polarization and polarization position angle are found to be rotationally modulated. The levels of polarization observed in LO Peg could be the result of scattering of an anisotropic stellar radiation field by an optically thin circumstellar envelope or scattering of the stellar radiation by prominence-like structures. The long term photometric observations of LO Peg indicate three independent groups of spots are present on the surface of LO Peg.

Some problems concerning the terrestrial atmosphere above about the 100 km level

1959 ◽  
Vol 253 (1275) ◽  
pp. 451-462 ◽  
Keyword(s):  
Temperature Gradient ◽  
Ionizing Radiation ◽  
Interplanetary Space ◽  
Alternative View ◽  
Final Conclusion ◽  
Analytic Model ◽  
The Sun ◽  
Hydrogen Atoms ◽  
Terrestrial Atmosphere

Consideration is given to the significance of recent rocket and satellite studies relating to the structure of the thermosphere. It is shown that unless hydrogen atoms are being captured very rapidly from interplanetary space they must be very rare indeed at the base of the exosphere. Stress is laid oil the importance of the steepness of the temperature gradient above the E layer in connexion with the thermal economy. Though no final conclusion is reached, it is thought that the view that the ionizing radiation from the sun is the main source of heat is more attractive than any alternative view yet put forward. An analytic model of the thermosphere is described in the appendix.

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