Wolken: a night sky drawn live by one shader. A moon in tonight's real phase hangs over a flat horizon where the dark silhouette of a sleeping city shows a few lit windows and the red lights of antennas. A layer of volumetric clouds drifts in the wind and is lit by the moon, with silver edges where the clouds pass in front of it and a faint warm glow on their undersides from the city. Stars shine through the gaps. Dragging looks around, the wheel or a pinch zooms. Five presets go from a clear sky over scattered fleecy clouds and a fast-moving layer to a closed overcast deck and a dark storm. The toolbar switches presets, coverage, wind, the moon's height, the render quality, pauses, saves a picture, copies a link and opens the help.