Asperatus formation, Canterbury, New Zealand (click here)
This one's so rare it doesn't even have official classification. "Undulatus asperatus" is its proposed designation, and if accepted as a new form by meteorologists, it'll be the first such addition since 1951. As of now, it's just another example of New Zealand having the coolest freakin' landscapes.
This is New Zealand. The country that is approximately 1000 miles away from the Antarctica coastline. New Zealands weather is effected by Antarctica. And now we have a warming planet with a melting South Pole and what appears in the sky? Some of the densest cloud formations ever witnessed by humans.This is not normal, no matter how fascinating it is.