PRESSURE ALTITUDE Meaning and
Definition
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Pressure altitude refers to the vertical distance above a standard reference plane where, hypothetically, the atmospheric pressure is standardized at 29.92 inches of mercury (inHg) or 1013.25 hectopascals (hPa). It is often used in aviation and meteorology to estimate an aircraft or object's height above mean sea level (MSL) based on atmospheric pressure measurements.
To calculate pressure altitude, one adjusts the altitude reading on an altimeter by compensating for variations in atmospheric pressure. This correction accounts for differences in barometric pressure readings at different locations and elevations. The standard pressure used as a reference is set to represent average sea-level conditions.
Pressure altitude is an important measurement for determining an aircraft's performance as it helps pilots assess engine power output and determine the aircraft's true altitude above the Earth's surface. It is particularly useful for aircraft operations at higher altitudes, where the air density decreases. By knowing the pressure altitude, pilots can calculate their true altitude above the ground, which is crucial for proper navigation and determining obstacle clearance.
In meteorology, pressure altitude is also utilized to assess the vertical distribution of atmospheric pressure. It is a vital component in weather forecasting and understanding air mass characteristics, as the variation in pressure with height affects the development and movement of weather systems. Additionally, pressure altitude aids in evaluating vertical wind profiles, which are key factors in aviation safety and meteorological research.
Etymology of PRESSURE ALTITUDE
The term "pressure altitude" is composed of two different words: "pressure" and "altitude".
1. Pressure: The word "pressure" comes from the Latin word "pressura", which means a pressing, a squeezing, or a compression. It is derived from the Latin verb "premere", which means "to press" or "to squeeze".
2. Altitude: The word "altitude" originates from the Latin word "altitudo", meaning height or elevation. It is derived from the Latin verb "altus", which means "high" or "far".
Therefore, when combined, "pressure altitude" refers to the height or elevation above a specific reference point, calculated using atmospheric pressure as a measurement rather than the actual distance above sea level.
