Tuesday, 21 May, 2013

The Skogafoss is one of the biggest waterfalls in Iceland, and is especially beautiful in this stunning image under the aurora borealis. The Northern Lights are shining against a great sea of stars, including the constellation Ursa major, or Great Bear, home to the asterism — a recognizable cluster of stars — the Big Dipper. [...]

Clouds are made of uncountable tiny particles, either water droplets or ice crystals, or a mixture of the two, says Grant Petty, a professor of atmospheric and oceanic sciences at the University of Wisconsin-Madison. “The water droplets are usually about 10-20 micrometers across, or about one-twentieth of the diameter of the period at the end [...]