waht two units of air pressure are commonly used in weather reports

Here is a site that lists inches of mercury and millibars.

http://kids.earth.nasa.gov/archive/air_pressure/

I think units area and pressure

Units density and altitude

I think units are also units pressure

The two units of air pressure commonly used in weather reports are millibars (mb) and inches of mercury (inHg).

To understand how these units are used in weather reports, let's explain how air pressure is measured. Air pressure refers to the force exerted by the weight of the air above a certain point in the Earth's atmosphere. It is typically measured using a device called a barometer.

Now, let's explore the two units of air pressure used in weather reports:

1. Millibars (mb): Millibars are the most widely used unit of air pressure in meteorology. A millibar is equal to one-thousandth of a bar, where a bar is the atmospheric pressure at sea level. Millibars are used because they provide a more accurate representation of small changes in air pressure. For example, a typical air pressure reading might be around 1013 mb, which corresponds to standard atmospheric pressure at sea level.

2. Inches of Mercury (inHg): Another common unit of air pressure is inches of mercury. This unit derives its name from the use of a mercury-filled column in the barometer. In this system, the height of the mercury column is measured in inches to determine the air pressure. Standard atmospheric pressure at sea level is roughly equivalent to 29.92 inHg.

In weather reports, you will often see both millibars and inches of mercury used interchangeably. For example, a weather forecast might indicate a pressure of 1013 mb or 29.92 inHg, or both. It's important to remember that these units represent the same air pressure but are expressed in different scales.

To convert between millibars and inches of mercury, you can use conversion factors. One inch of mercury is approximately equal to 33.864 millibars, or conversely, one millibar is approximately equal to 0.02953 inches of mercury.

In summary, millibars (mb) and inches of mercury (inHg) are the two commonly used units for measuring air pressure in weather reports. They represent the force exerted by the weight of the air above a given point in the atmosphere and can be converted between each other using conversion factors.