High pressure area

A high pressure area is a region where the atmospheric pressure is higher than in the surrounding air. It is usually linked with sinking air, more stable weather, and often good visibility, though haze or fog can form especially in calm conditions. In flight planning, you should still check for local effects such as strong pressure gradients, temperature inversions, or reduced visibility near the surface. When flying from high pressure to lower pressure without resetting the altimeter, your true altitude becomes lower than indicated.