Very strange clouds appeared in Norway on December 16th:
dtlange at Robertscribbler
noted:
Nacreous clouds appear around the Arctic Circle
Polar stratospheric clouds, also known as
nacreous clouds (from nacre, or mother of pearl), are icy structures that form in the lower stratosphere (15 – 25 km) when temperatures drop to around -85 ºC (-121 ºF). They are best observed when the Sun is between 1 and 6 degrees below the horizon.
“High-altitude sunlight shining through tiny ice particles ~10µm across produce the characteristic bright iridescent colors by diffraction and interference. Once thought to be mere curiosities, some PSCs are now known to be associated with the destruction of ozone,” Dr. Tony Phillips of the SpaceWeather.com explains.
Truls Tiller photographed these over Tromsø city, Norway, on December 16, 2015:
http://robertscribbler.com/2015/12/14/1-06-c-above-1880-climate-year-2015-shatters-all-previous-records-for-hottest-ever-recorded/?cpage=1#comment-60628
