Earth's rarest clouds are looking pretty good right now. The most uncommon sort of cloud, known as noctilucent or "night-shining" clouds, only appear after the Sun has set or just before it rises. They show in the Northern Hemisphere sky for only a few months each summer, but this year they are the most colorful in 15 years, so go outdoors and look up. Long, thin wisps … [Read more...] about This Summer, keep an Eye Out For Noctilucent clouds; they’re the best they’ve been in years