Quick Answer
Atmospheric pressure plays a crucial role in altimeter readings as it affects the device's ability to accurately measure altitude. Changes in atmospheric pressure can cause altimeters to either over- or under-read altitude, resulting in incorrect navigation information.
Understanding Altimeter Errors
Altimeter readings are based on the principle that air pressure decreases with altitude. Most modern altimeters use a barometric system to measure pressure, which is then correlated to altitude. However, atmospheric pressure can fluctuate significantly due to weather patterns, temperature changes, and other factors. For example, a sudden drop in atmospheric pressure can cause an altimeter to read a higher altitude than the actual location. This can be particularly problematic for pilots navigating in mountainous or turbulent areas.
Correcting for Atmospheric Pressure
To minimize the impact of atmospheric pressure on altimeter readings, pilots and hikers often use a technique called “calibration” or “setting the altimeter to mean sea level pressure.” This involves setting the altimeter to match the current atmospheric pressure at sea level, which can be obtained from a weather forecast or by using a separate barometer. By doing so, the altimeter can be adjusted to provide a more accurate reading of altitude. For instance, setting the altimeter to 29.92 inches of mercury (1013.25 millibars) is a standard practice for aircraft, as this is the typical sea level pressure. This correction can improve altitude accuracy by up to 100 feet (30 meters) in some cases.
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