How do high- and low-pressure systems form?
When it comes to weather, everything is relative. That is, the center of high pressure or the center or low pressure simply means that the atmospheric pressure reading at that point is higher or lower than readings from all other surrounding locations. High-pressure systems usually form where air converges high above in the atmosphere. As the air converges aloft, its own weight forces it to sink. The sinking air spirals outward, clockwise in the Northern Hemisphere, counterclockwise south of the Equator. Low-pressure systems often form where the air diverges aloft, allowing for air from lower levels to rise. As air rises, it cools and often condenses into clouds and precipitation. . There’s plenty more about highs and lows on this USA TODAY resource page.
