Ray Popkin (Member 63,500) was out for an early morning walk along the beach at Boca Raton, Florida, US as a squall offshore lingered in the soft blue light that comes just before sunrise.

This moment is known as the blue hour. It occurs when the Sun is just below the horizon, and so the surroundings are predominantly lit not by direct sunlight like the tall Cumulus congestus cloud in the distance here but by indirect sunlight that has been scattered from the atmosphere. This indirect light fills the shadows. Its mix of wavelengths have had warmer-looking tones filtered out by the scattering effect of the air. It’s why the ridge-like cloud feature, known as an arcus, and the rest of the cloud bank it extends along is bathed in a soft, cool blue.

Rise early, like Ray did, while the Sun’s still tucked behind the horizon and the world’s still waking up, and you too might catch the magical light of dawn’s blue hour.