condition mean min max 4 h after light 6.2 6.2 6.2 8 h after light 17.6 3.7 31.5 12 h after light 16.65 6.1 27.2 4 h after dark 30.75 16.5 45.0 8 h after dark 13.7 4.2 23.2 12 h after dark 1.8 1.8 1.8