Pictured here is a beautiful noctilucent cloud display, in the northern skies over Okanagan Lake in British Columbia’s south interior. Noctilucent clouds are the highest type of cloud that exists. They are seen most often at latitudes between 50 and 65 degrees north, during the late spring and summer months. While most clouds form below 7.6 kilometres altitude (25,000 feet), noctilucent clouds typically form around ten times higher, 80 kilometres (260,000 feet) above sea level. Because of their extreme altitude, noctilucent clouds (or night shining clouds) remain illuminated by the sun long after the sun sets below the horizon, resulting in a beautiful spectacle of glowing clouds against a dark twilight backdrop. Many mysteries about the formation of these clouds are yet to be unraveled by researchers, but they seem to be occurring more frequently as climate change and certain types of greenhouse gas emissions intensify.