Millibar
The millibar (mb) is commonly used in meteorology. The millibar is a metric unit of pressure equivalent to 100 pascals. Standard Earth atmospheric pressure at sea level is approx 1013.25 millibars.
mm of mercury
The millimeter of mercury (mmHg) is pressure unit traditionally used in meteorology. It is the pressure from a 1 mm column of mercury at 0°C under normal gravity.