A low pressure system is a type of weather system characterized by a region of lower atmospheric pressure compared to the surrounding area. The two crossword solutions for this term are 'TROUGH' and 'CYCLONE'. A TROUGH is an elongated region of low atmospheric pressure, usually associated with areas of cloudiness and precipitation. A CYCLONE is a large-scale air mass that rotates around a center of low atmospheric pressure, typically bringing strong winds, heavy rain, and sometimes snow.