72 Seasons

Frost is ice crystals that form as the moisture in the air comes into contact with sub-zero degree objects. It appears often on clear, windless nights, and in the morning leaves and window panes are covered in a white sheet of ice crystals. The average day for the first frost (from 1981-2010), is 25 October in Sapporo, and 20 December in Tokyo. It comes much later nowadays than it used to, due to global warming, perhaps?
©Utsukushii Kurashikata Institute