The milibar is a unit of pressure used in meteorology and is equal to one thousandth of a bar, which is roughly equal to atmospheric pressure at sea level. It is commonly used to measure air pressure in weather reports and forecasts.
Usually, due to the relatively low value of the static pressure of a fan, the unit that this pressure is expressed is milibar, mm H2O, psi, mm Hg, kPa, hPa. In the US, inches H2O.
Pressure is shown with white curvy lines. The closer the lines are to each other in a certain area, the higher the pressure is. The farter apart they are, the lower the pressure is in that area.
atmospheric pressure in measured in millibars