極きょく中ちゅう間かん圏けん雲うん

noun

polar mesospheric clouds

Technical term in atmospheric science; refers to clouds in the polar mesosphere, also known as noctilucent clouds when visible at twilight.

• 極きょく中ちゅう間かん圏けん雲うんは、夏なつの高こう緯い度ど地ち方ほうで観かん測そくさ