'Nothing else looks like them': Saving Japan's exceptionally rare 'snow monsters'

At Mount Zao, these formations occur during sustained westerly winds of up to 26m per second (85ft per second), with surface air temperatures between -6.3C to -0.1C (21-31F) and unusually high cloud liquid water content. Under these precise conditions, the rime thickens on the windward side of trees into overlapping ridges known as "shrimp tails", the distinctive shapes that cluster together to form the towering juhyo figures.

"Because such precise meteorological and ecological conditions align in very few places, Zao's snow monsters are a phenomenon almost unique to northern Japan," says Fumitaka Yanagisawa, an emeritus professor of geochemistry who studies the juhyo at Yamagata University.

The snow monsters are the biggest winter draw of the Zao area, a mountain range which lies between Japan's Yamagata and Miyagi prefectures and attracts tens of thousands of visitors annually.