INCHES OF MERCURY Meaning and
Definition
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Inches of Mercury (inHg) is a unit of measurement used in meteorology to quantify atmospheric pressure. It refers to the height of a column of mercury that can be supported by the atmospheric pressure exerted on the mercury in a barometer. This unit is commonly used in the United States.
The term "inches of mercury" comes from the use of a mercury barometer, a device invented by Evangelista Torricelli in the 17th century. A mercury barometer consists of a glass tube filled with mercury, which is then inverted into a dish of mercury. The atmospheric pressure pushes down on the mercury in the dish, causing it to rise in the glass tube. The height of the column of mercury is measured in inches, indicating the pressure exerted by the atmosphere.
The standard atmospheric pressure at sea level is approximately 29.92 inches of mercury, equivalent to 1 atmosphere (atm). This value is often used as a reference point for measuring pressure variations. In meteorology, the inches of mercury unit is commonly used to report barometric pressure and indicate changes in weather patterns. High-pressure systems are associated with larger inches of mercury readings, indicating stable and fair weather conditions, while low-pressure systems are associated with lower measurements, indicating the possibility of clouds, precipitation, and unstable weather.
