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れることが多おおい。

  Polar mesospheric clouds are often observed in high-latitude regions during summer.