In the Northern Hemisphere, Earth's rotation causes winds to blow counterclockwise around a low-pressure system and converge. Around a high pressure system, the winds blow clockwise and diverge.
In a High Pressure System, cool, dense air sinks and clouds cannot form. High pressure systems often bring clear skies and fair weather. In a lower pressure system, warm less dense air rises. This rising air cools as water vapor in the air condenses. Therefore, a low-pressure system is often associated with cloudy weather and precipitation.