Effect van atmosferische condities op de nachtelijke hemelhelderheid
Effects of meteorological and atmospheric parameters on night sky brightness
07 July 2012, PDF |
36 pages |
Lolkema DE, Haaima M, den Outer PN, Spoelstra H
RIVM Report 680151002
Clouds reflect light. This causes light to be seen tens of kilometres away from the light source. There is a clear correlation between night sky brightness and the cloud height and cover. So the light emission being the same, night sky brightness can be quite variable. This means that also the exposure of humans, animals and plants to light at night varies. RIVM has investigated the effect of atmospheric conditions on night sky brightness. The sky close to a strong light source, like a greenhouse, a large city or an industrial area, can be quite dark on clear nights, i.e., without clouds or an optically thick aerosol layer. But on cloudy nights this same sky can be very bright, due to light scattering by these same clouds. Light at night effects humans, plants and animals. The use of light at night has numerous advantages but also adverse effects on flora, fauna and humans. It affects the foraging, reproductive and migration behaviour of a number of nocturnal animals such as insects, bats, amphibians and birds. It changes prey-predator relationships, affects animal's natural rhythms, and disrupts physiological processes in plants. It might cause a disruption of the human circadian system. The exposure however, of humans, plants and animals is far from known. This information is necessary in order to determine the impact of night time lighting. Exposure depends on the light emission on the one hand and on the atmospheric conditions on the other. Light emissions can be monitored with future satellite instruments. It is already possible to determine the night sky brightness from this with model calculations, but only for one atmospheric condition. Up to now, night sky brightness cannot be determined with model calculations for cloudy, partly cloudy or dust polluted conditions. The results of this and future research are essential to map night sky brightness for different atmospheric conditions.