noun
cold air mass
Meteorological term for a large body of cold air. Used in weather forecasts and scientific contexts.
寒気団が南下すると、気温が急に下がります。
When a cold air mass moves south, the temperature drops sharply.
気団 is the general term for an air mass; 寒気団 specifies a cold one.
Compound of 寒 (cold) + 気団 (air mass). The term 気団 is a modern meteorological coinage.