expression, noun
low pressure trough
A meteorological term for an elongated area of low atmospheric pressure, often associated with cloudy or rainy weather. Used in weather forecasts and scientific contexts.
明日は気圧の谷の影響で天気が崩れるでしょう。
Tomorrow the weather will likely worsen due to a low pressure trough.
Compound of 気圧 (atmospheric pressure) + の (possessive particle) + 谷 (valley), literally 'valley of atmospheric pressure'. A calque from English 'pressure trough' or similar meteorological terminology.