A high pressure system represents an area of higher pressure at the surface where winds blow clockwise around its center. Clear, sunny weather is often associated with high pressure because descending air becomes warmer and drier. At sea level air pressure is normally around 1013.25mb (29.92 inches of mercury).
As explained on the previous page, dry air is heavier than moist air because water vapor is lighter than air itself.
A high pressure system represents an area of higher pressure at the surface where winds blow clockwise around its center. Clear, sunny weather is often associated with high pressure because descending air becomes warmer and drier. At sea level air pressure is normally around 1013.25mb (29.92 inches of mercury).