noun
Arctic air mass
Technical term in meteorology referring to a cold air mass originating in the Arctic region.
北極気団の南下により、日本列島は厳しい寒波に見舞われた。
Due to the southward movement of an Arctic air mass, the Japanese archipelago was hit by a severe cold wave.
Compound of 北極 (ほっきょく, 'Arctic') and 気団 (きだん, 'air mass').