Atmospheres
The atmosphere (atm) is a unit of pressure being equal to 101,325 pascals. It is based on the average atmospheric pressure at sea level on Earth.
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.