Have you ever heard of or seen Noctilucent Clouds (NLCs)? These magnificent clouds are wavy, thin, electric blue clouds that form very high in the atmosphere, at about 80 to 90 km above the Earth's surface.
At one point you had to travel to polar latitudes to see NLCs, but in recent years they have been reported as far south as Denver, Colorado. The clouds are seasonal and usually appear in the northern hemisphere in between mid-May and the end of August, around sunrise or sunset.
According to a recent article by NASA, NLCs appeared remarkably early this season. That could mean brighter clouds and wider visibility than ever before! So keep an eye out for these beautiful clouds this summer, maybe you will catch a glimpse!
Dave Hughes photographed the NLCs near Edmonton, Alberta Canada on July 2, 2011. Credit: NASA/Dave Hughes.