What effect do warmer temperatures have on the altimeter reading?

When temperatures are warmer than the standard atmospheric conditions assumed by the altimeter calibrations, the device will indicate an altitude that is lower than the true altitude. This occurs because altimeters are designed to measure air pressure, which decreases with altitude. However, when temperatures rise, the air becomes less dense than what is expected at standard conditions, leading to a lower pressure reading at a given altitude. Consequently, the altimeter interprets this lower pressure as being at a lower altitude than the actual position of the aircraft.

Understanding this principle is crucial for pilots, as reliance on inaccurate altimeter readings due to temperature variations can be dangerous during takeoff, flight, and landing. Accurate altitude awareness is essential for safe navigation and collision avoidance. Therefore, awareness of how temperature affects altimeter readings is an important aspect of flight operations.