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Kocifaj, M. |
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Title |
Two-stream approximation for rapid modeling the light pollution levels in local atmosphere |
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2012 |
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Astrophysics and Space Science |
Abbreviated Journal |
Astrophys Space Sci |
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341 |
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2 |
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301-307 |
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Light pollution; Atmospheric effects; Methods: numerical; Radiative transfer; Scattering; modeling; two-stream approximation |
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Abstract |
The two-stream concept is used for modeling the radiative transfer in Earth's atmosphere illuminated by ground-based light sources. The light pollution levels (illuminance and irradiance) are computed for various aerosol microphysical parameters, specifically the asymmetry parameter g A , single scattering albedo ω A , and optical thickness τ A . Two distinct size distributions of Junge's and gamma-type are employed. Rather then being a monotonic function of τ A , the diffuse illuminance/irradiance shows a local minimum at specific τ A, lim independent of size distribution taken into consideration. The existence of local minima has relation to the scattering and attenuation efficiencies both of which have opposite effects. The computational scheme introduced in this paper is advantageous especially if the entire set of calculations needs to be repeated with an aim to simulate diffuse light in various situations and when altering optical states of the atmospheric environment. |
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0004-640X |
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IDA @ john @ |
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273 |
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Author |
Kocifaj, M. |
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Title |
Light-pollution model for cloudy and cloudless night skies with ground-based light sources |
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Journal Article |
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Year |
2007 |
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Applied Optics |
Abbreviated Journal |
Appl. Opt. |
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46 |
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15 |
Pages |
3013 |
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Keywords |
light pollution; modeling |
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The scalable theoretical model of light pollution for ground sources is presented. The model is successfully employed for simulation of angular behavior of the spectral and integral sky radiance and∕or luminance during nighttime. There is no restriction on the number of ground-based light sources or on the spatial distribution of these sources in the vicinity of the measuring point (i.e., both distances and azimuth angles of the light sources are configurable). The model is applicable for real finite-dimensional surface sources with defined spectral and angular radiating properties contrary to frequently used point-source approximations. The influence of the atmosphere on the transmitted radiation is formulated in terms of aerosol and molecular optical properties. Altitude and spectral reflectance of a cloud layer are the main factors introduced for simulation of cloudy and∕or overcast conditions. The derived equations are translated into numerically fast code, and it is possible to repeat the entire set of calculations in real time. The parametric character of the model enables its efficient usage by illuminating engineers and∕or astronomers in the study of various light-pollution situations. Some examples of numerical runs in the form of graphical results are presented. |
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0003-6935 |
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IDA @ john @ |
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277 |
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Author |
Xavier Kerola, D. |
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Modelling artificial night-sky brightness with a polarized multiple scattering radiative transfer computer code: Modelling artificial night-sky brightness |
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2006 |
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Monthly Notices of the Royal Astronomical Society |
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365 |
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4 |
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1295-1299 |
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Skyglow; modeling; radiative transfer; Gauss-Seidel; light pollution; Garstang model |
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As part of an ongoing investigation of radiative effects produced by hazy atmospheres, computational procedures have been developed for use in determining the brightening of the night sky as a result of urban illumination. The downwardly and upwardly directed radiances of multiply scattered light from an offending metropolitan source are computed by a straightforward Gauss-Seidel (G-S) iterative technique applied directly to the integrated form of Chandrasekhar's vectorized radiative transfer equation. Initial benchmark night-sky brightness tests of the present G-S model using fully consistent optical emission and extinction input parameters yield very encouraging results when compared with the double scattering treatment of Garstang, the only full-fledged previously available model. |
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0035-8711 |
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IDA @ john @ |
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278 |
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Author |
Boyce, P.R. |
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Title |
Review: The Impact of Light in Buildings on Human Health |
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Journal Article |
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2010 |
Publication |
Indoor and Built Environment |
Abbreviated Journal |
Indoor and Built Environment |
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19 |
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1 |
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8-20 |
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Keywords |
Human Health; indoor light; circadian disruption; shift work; oncogenesis; Review |
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The effects of light on health can be divided into three sections. The first is that of light as radiation. Exposure to the ultraviolet, visible, and infrared radiation produced by light sources can damage both the eye and skin, through both thermal and photochemical mechanisms. Such damage is rare for indoor lighting installations designed for vision but can occur in some situations. The second is light operating through the visual system. Lighting enables us to see but lighting conditions that cause visual discomfort are likely to lead to eyestrain. Anyone who frequently experiences eyestrain is not enjoying the best of health. The lighting conditions that cause visual discomfort in buildings are well known and easily avoided. The third is light operating through the circadian system. This is known to influence sleep patterns and believed to be linked to the development of breast cancer among night shift workers. There is still much to learn about the impact of light on human health but what is known is enough to ensure that the topic requires the attention of all those concerned with the lighting of buildings. |
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Rensselaer Polytechnic Institute, New York, USA |
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1420-326X |
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IDA @ john @ |
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292 |
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Author |
LeGates, T.A.; Fernandez, D.C.; Hattar, S. |
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Title |
Light as a central modulator of circadian rhythms, sleep and affect |
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Journal Article |
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Year |
2014 |
Publication |
Nature Reviews. Neuroscience |
Abbreviated Journal |
Nat Rev Neurosci |
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15 |
Issue |
7 |
Pages |
443-454 |
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Keywords |
Human Health; photobiology; circadian disruption; asynchronization; sleep; mood; Review |
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Light has profoundly influenced the evolution of life on earth. As widely appreciated, light enables us to generate images of our environment. However, light – through intrinsically photosensitive retinal ganglion cells (ipRGCs) – also influences behaviours that are essential for our health and quality of life but are independent of image formation. These include the synchronization of the circadian clock to the solar day, tracking of seasonal changes and the regulation of sleep. Irregular light environments lead to problems in circadian rhythms and sleep, which eventually cause mood and learning deficits. Recently, it was found that irregular light can also directly affect mood and learning without producing major disruptions in circadian rhythms and sleep. In this Review, we discuss the indirect and direct influence of light on mood and learning, and provide a model for how light, the circadian clock and sleep interact to influence mood and cognitive functions. |
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1] Johns Hopkins University, Department of Biology, Baltimore, Maryland 21218, USA. [2] Johns Hopkins University, Department of Neuroscience, Baltimore, Maryland 21218, USA |
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English |
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1471-003X |
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PMID:24917305 |
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IDA @ john @ |
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299 |
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