Landscape lighting as a source of light pollution - the effect of the seasons on this phenomenon

Outdoor lighting can be a source of undesirable phenomena known as light pollution. Too much of light pollution has consequences: it washes out starlight in the night sky, interferes with astronomical research, disrupts ecosystems, has adverse health effects and finally energy is wasted. The amount of light pollution mostly depends on the type of light source (it's spectral power distribution) and the luminaire intensity distribution curve. Also the placement and the reflective properties of the surface around it e.g. the walls of buildings, asphalt, grass, etc. are important. In this paper the analysis of factors describing amount of light pollution in the park alleys was carried out. The model of park path, with trees, shrubs, benches and grassy paths, illuminated by typical lighting luminaires, used in such applications, was done by professional lighting design software. Computations of light pollutions factors were done for MH, HPS, LED warm light and LED cold light lamps used in opal sphere type luminaires, used for the lighting of given park alley. The seasonal variation of landscape color and the amount of seasonal vegetation was taken under consideration. According to our calculations the amount of light pollution in landscape areas has a strong correlation with the season of the year. Additionally this effect, for each season, depends on the lamp's type.