Fig.38 - The Aletsch Glacier at night. Nikon Z6 II, Nikon Z 20mm f/1.8S lens (July 22, 2023). Stack of twenty images with 10 s exposure time at f/2.8 and ISO 4000 and a single image with 60 s expsoure time at f/2.8 and ISO 100 during blue hour. During blue hour, the Sun is below the horizon and the blue part of sunlight is scattered in the atmosphere.