How do colder than standard temperatures affect an altimeter reading?

In colder than standard temperatures, an altimeter reading is affected due to the principles of atmospheric pressure and how altimeters are calibrated. Altimeters are designed to measure altitude based on the standard atmosphere, which assumes a specific temperature and pressure profile. When temperatures are colder than standard, the air density is higher than what the altimeter settings are calibrated for.

As a result, the altimeter will indicate a higher altitude than the actual altitude. This discrepancy occurs because, in colder air, the pressure levels are higher at a given altitude compared to warmer conditions where the air is less dense. Consequently, if a pilot follows the altimeter setting without adjusting for the lower temperatures, they may believe they are at a higher elevation than they truly are, which could lead to dangerous situations, particularly when flying at low altitudes.

Understanding this relationship is crucial for pilots in order to accurately assess their altitude and maintain safe flight operations, particularly in colder weather conditions.