高气压是指一个气压高于周边地区的区域，是为反气旋。在北半球高气压区域内的空气作顺时针方向旋转，在南半球则逆时针方向。高气压区一般风力比较小，空气下沉。通过绝热过程下沉气流一般使得500米以下的造成云或者雾的水滴蒸发，因此高气压区通常天气晴朗。在白天，由于没有云来反射阳光或者地面的热量，在夏季高气压区比较热，而在冬季则比较冷。在夜间由于没有云阻挡热量的散失，气温一般不论在哪个季节都比较低。

高气压区由副热带高压造成，它是由于赤道的空气上升形成的，上升的热空气冷却，失去湿度，同时被向高纬度的方向运输，在这个过程中它下降，导致高气压区。这个过程也被称为哈德里环流圈。世界上许多沙漠地区与高气压区的形成有直接的关联。

A high-pressure area, high or anticyclone is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment.

Winds within high-pressure areas flow outward from the higher pressure areas near their centers towards the lower pressure areas further from their centers. Gravity adds to the forces causing this general movement, because the higher pressure compresses the column of air near the center of the area into greater density – and so greater weight compared to lower pressure, lower density, and lower weight of the air outside the center.