The North American record for highest recorded barometric pressure is 31.85 in Hg, set in 1989 in Northway, Alaska. Convert this pressure to: \begin{equation}\begin{array}{ll}{\text { a. } \mathrm{mmHg}} & {\text { b. } \mathrm{atm}} \\ {\text { c. torr }} & {\text { d. } \mathrm{kPa}(\text { kilopascals })}\end{array}\end{equation}

The concept of a conversion factor is at the heart of unit conversions, such as changing measurements of barometric pressure from one unit to another. A conversion factor is a numerical value or equation used to multiply or divide a quantity to express the same physical amount in different units. For instance, with barometric pressure, a conversion factor can equate inches of mercury (in Hg) to millimeters of mercury (mmHg), atmospheres (atm), torr, or kilopascals (kPa).

Understanding conversion factors is crucial because they allow for accurate and consistent communication of measurements in science and various fields. In the example of converting 31.85 in Hg to different units, specific conversion factors such as \( 25.4 \) for mmHg, \( 29.92 \) for atm, and \( 3.38639 \) for kPa are applied to obtain the correct values in each measurement unit. The use of correct conversion factors ensures that whether you are predicting weather patterns or engineering a pressure-sensitive system, the measurements you work with are precise and reliable.

Atmospheric pressure is the force exerted by the weight of the air in the Earth's atmosphere. It is an essential parameter in meteorology and has profound effects on weather and climate. Barometric pressure is a common way to measure atmospheric pressure. A barometer, which can be an aneroid or a mercury barometer, is used to measure the air pressure and provides readings in various units.

The process of measuring atmospheric pressure involves comparing the weight of the air above the barometer at a specific elevation to a defined measure. This measurement then translates into different units based on the type of barometer and the preferred units for the context, whether scientific, aviation, or maritime. For example, the North American record for the highest recorded barometric pressure of 31.85 in Hg reflects a significant atmospheric weight on the barometer, indicating a particularly high air pressure situation, leading to it being noted in historical records.

Units of pressure are various standards that are used to express the intensity of pressure. The common units include inches of mercury (in Hg), millimeters of mercury (mmHg), atmospheres (atm), torr, and kilopascals (kPa) among others. Each unit of pressure reflects the force exerted per unit area.

Inches of mercury and millimeters of mercury are direct measurements derived from the displacement of mercury in a mercury barometer. An atmosphere is a unit of pressure that is roughly equivalent to the average air pressure at sea level on Earth. The torr is named after Evangelista Torricelli, an Italian physicist and mathematician, and one torr approximately equals the pressure exerted by a one-millimeter column of mercury. Kilopascals are part of the International System of Units (SI) and are widely used in science and engineering, with one kilopascal equaling a thousand pascals. The conversion from one unit to another, as seen in the textbook exercise, allows for flexibility and precision across different scientific and technical contexts.