A weather system is composed of a FRONT, a LOW pressure area, and a HIGH pressure area. A FRONT is a boundary between two air masses of different densities, usually associated with a change in temperature and humidity. A LOW pressure area is an area of lower atmospheric pressure relative to its surroundings, which can cause clouds and precipitation. A HIGH pressure area is an area of higher atmospheric pressure relative to its surroundings, which can cause clear skies and dry weather. Together, these three components form a weather system.