High-pressure system

Connection to wind

Atmospheric air flows from areas of high pressure to areas of low pressure resulting in wind. Since stronger high-pressure systems contain cooler or drier air, the air mass is more dense and flows towards areas that are warm or moist where air is less dense and atmospheric pressure at the surface is lower. The larger the pressure difference between a high-pressure system and a low-pressure system, the higher the wind speed. The coriolis force caused by the Earth's rotation is what gives winds within high-pressure systems their clockwise circulation in the northern hemisphere (as the wind moves outward and is deflected right from the center of high pressure) and counterclockwise circulation in the southern hemisphere (as the wind moves outward and is deflected left from the center of high pressure). Friction with land slows down the wind flowing out of high-pressure systems and causes wind to flow more outward than would be the case in the absence of friction. This results in the 'actual wind' or 'true wind', including ageostrophic corrections, which add to the geostrophic wind that is characterized by flow parallel to the isobars.