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1

Variation in Direct Solar Irradiation with Relative Humidity and Atmospheric Temperature

Wazwaz Aref, Khan Mohd Shariq

Journal of Ecological Engineering

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2019

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Vol. 20, nr 9

38--43

EN

A class first Pyranometer was used to measure the direct solar irradiation and the obtained results were analyzed. Separate sensors were used to measure the relative humidity and the atmospheric temperature (RH/AT sensors). The measurements were conducted for the whole year of 2013. The author analyzed the collected solar data during one day, month, and year. The maximum, minimum, average, and accumulative solar irradiation (SR) were calculated and analyzed with connection to relative humidity and atmospheric temperature. The author found that April was characterized by the average maximum solar irradiation (SR= 1112±1W/m2), May had the maximum SR accumulation (13276552± 1W/m2). The maximum average percentage relative humidity found in July (% RH = 97± 3%), while the minimum average % RH is in December (% RH = 25± 3%). In May, the maximum average atmospheric temperature was 36.0 ± 0.6°C, while the average minimum was in January (AT= 19.1 ± 0.6°C). The total accumulation of solar flux during the year 2013 is 222 ± 1MW/m2.

2

Wpływ zachmurzenia okołosłonecznego na szczytowe wartości natężenia promieniowania słonecznego

Czekalski D.

Ciepłownictwo, Ogrzewnictwo, Wentylacja

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2015

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T. 46, nr 7

252--255

PL

Wysoka wartość albedo chmur rodzajów Cumulus, Cumulonimbus i Stratus sprawia, że ich obecność w okolicy tarczy słonecznej intensyfikuje składową rozproszoną promieniowania słonecznego. W takich warunkach szczytowe wartości osiąga natężenie promieniowania całkowitego. Zjawisko okresowych wzrostów natężenia promieniowania słonecznego do wartości szczytowych zilustrowano z wykorzystaniem wykresów przebiegów natężenia promieniowania słonecznego całkowitego i składowej bezpośredniej na płaszczyźnie śledzącej dwuosiowo pozycję Słońca oraz fotografii nieboskłonu. Wartości chwilowe dochodzą na płaszczyznach pochyłych do 1200 W/m2. W przedziałach 3 minutowych może to być maksymalnie 1150 W/m2, 5 minutowych 1120 W/m2, a 10 minutowych 1100 W/m2.

EN

The high value of albedo of Cumulus, Cumulonimbus and Stratus clouds and their presence in the area of solar disk result in the increased intensity of the diffuse component of the solar radiation. In such conditions, the value of intensity of global solar radiation reaches its peak. The phenomenon of periodic increases in solar radiation to the peak values has been illustrated with the plots of global solar radiation and direct normal component on a two-axis plane tracking the position of the Sun, along with photographs of the sky. Instantaneous values reach on tilted plane up to 1200 W/m2, maximally 1150, 1120 and 1100 W/m2 during periods of 3, 5 and 10 minutes respectively.

3

Uncertainty in stratiform cloud optical thickness inferred from pyranometer measurements at the sea surface

Rozwadowska A.

Oceanologia

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2004

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No. 46 (2)

155-174

EN

The relative "plane-parallel" error in a mean cloud optical thickness retrieved from ground-based pyranometer measurements is estimated. The plane-parallel error is defined as the bias introduced by the assumption in the radiative transfer model used in cloud optical thickness retrievals that the atmosphere, including clouds, is horizontally homogeneous on the scale of an individual retrieval. The error is estimated for the optical thickness averaged over the whole domain, which simulates the mean cloud optical thickness obtained from a time series of irradiance measurements. The study is based on 3D Monte Carlo radiative transfer simulations for non-absorbing, all-liquid, layer clouds. Liquid water path distributions in the clouds are simulated by a bounded cascade fractal model. The sensitivity of the error is studied with respect to the following factors: averaging time of irradiance used in an individual retrieval, mean cloud optical thickness, cloud variability, cloud base height and solar zenith angle. In the simulations presented in this paper, the relative bias in the domain averaged cloud optical thickness retrieved from pyranometer measurements varies from +1% for optically thin clouds to nearly -20%. The highest absolute value of the relative bias is expected for thick and variable clouds with high bases (e.g. 1 km) and retrievals based on long-term mean irradiances (averaging time of the order of several tens of minutes or hours). The bias can be diminished by using short-term irradiance averages, e.g. of one minute, and by limiting retrievals to low-level clouds.