Inches of Mercury
Inches of Mercury (inHg) are used to measure pressure in the imperial system. Traditionally this unit is used in the United States for barometric pressure in weather reports. It is the pressure from a column of mercury exactly one inch high at standard gravity.
Millibar
A millibar (mb) is a metric unit of pressure equal to 100 pascals, or one hectopascal. Standard atmospheric pressure at sea level is 1,013.25 millibars, and weather forecasts quote air pressure in them.