Strange, Glowing Night Clouds Continue to Spread Just after summer sunsets in northern latitudes, shimmering, wispy clouds appear in the twilight sky. This year, these noctilucent clouds have appeared earlier and farther south than ever before.
June 13, 2013 - Wired News
An Early Start for Noctilucent Clouds The season for noctilucent “night-shining” clouds is arriving in the northern hemisphere, when wispy, glowing tendrils of high-altitude ice crystals may be seen around the upper latitudes, shining long after the Sun has set. Found about 83 km (51 miles) up, noctilucent clouds (also called polar mesospheric clouds) are the highest cloud formations in the [...]
June 10, 2013 - Universe Today