(Wired) 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.
Noctilucent clouds exist higher in Earth’s atmosphere than any other cloud type. First observed in 1885 following the eruption of Krakatoa, they were a sight reserved for Earth’s northernmost residents. In recent years, however, their intensity and frequency have increased, often at latitudes previously thought to be too far south for noctilucent clouds to form.
Noctilucent clouds over the North Pole, June 10, 2013 (LASP/Univ. of Colorado)
In 2009, scientists from the National Center for Atmospheric Research pointed to the southern creep of noctilucent clouds as an early warning signal for climate change high in the atmosphere. Now, new data from NASA’s cloud-observing AIM satellite supports this possibility.
