What are the two standard units of atmospheric pressure?

The two standard units of atmospheric pressure that are commonly used in meteorology are inches of mercury and millibars.

Inches of mercury (inHg) is a traditional unit used primarily in the United States. It is derived from the height of a column of mercury that can be supported by atmospheric pressure. Meteorological pressure readings in inches of mercury are often seen in weather forecasts and reports.

Millibars, on the other hand, is a metric unit that is widely used internationally. It is a part of the metric system based on the centibar, which is one one-hundredth of a bar. Millibars provide a convenient way to represent atmospheric pressures, and they are particularly useful in meteorological applications, where atmospheric pressure plays a crucial role in weather systems and forecasting.

Both of these units are essential for meteorologists and weather enthusiasts to measure and compare atmospheric pressure effectively, ensuring a common understanding of pressure systems in weather patterns. Other options like Pascals and pounds per square inch also measure pressure but are not as commonly used in meteorological contexts compared to inches of mercury and millibars.