Darkness card, sky brightness with greenhouse lighting on

The map deals with the sky brightness in North Holland in 2011-2012 with greenhouse lighting on. If there is no direct enlightenment nearby, the night sky determines the degree of darkness. The sky is lit up by shining light from a city or greenhouse from an area with a radius of about 30 kilometers. In 2011 and 2012, 225 locations in the province of North Holland measured the brightness of the sky in the point straight up (zenit), as a measure of the ‘darkness’. Previously carried out measurements in Amsterdam and on the island of Texel have also been incorporated into this darkness map.本数据集对应的夜空亮度地图，呈现了2011至2012年北荷兰省（North Holland）在温室照明开启状态下的天空亮度分布。若测点附近无直接人工光照，夜空的固有状态将决定其自身的黑暗程度。该区域约30公里半径范围内的城市与温室所散发的光线，会对夜空造成光污染照明。2011至2012年间，研究人员在北荷兰省的225个测点对天顶（zenith）方向的天空亮度开展了测量，以此作为夜空黑暗程度的量化指标。此前在阿姆斯特丹及特塞尔岛（Texel）完成的测量数据，也已被纳入该夜空黑暗度地图。