According to the ICAO Standard Atmosphere, how does temperature change with altitude?

In the context of the ICAO Standard Atmosphere, the temperature profile defines how temperature decreases with altitude in a predictable manner. Specifically, temperature decreases at a rate of approximately 6.5°C for every 1,000 meters (or roughly 2°C for every 1,000 feet) up to a certain altitude.

According to the standard atmosphere model, this decrease continues up to approximately 36,090 feet (11,000 meters), where the temperature reaches a point known as the tropopause. At this altitude, the temperature stabilizes and remains constant for a significant portion of the stratosphere.

Thus, the correct understanding is that temperature decreases at the specified rate up to 65,617 feet (20,000 meters) and then remains constant. This aligns with the correct answer, which accurately reflects that after the initial decline in temperature with altitude, it levels off without further decrease up to the specified altitude.

This temperature profile is crucial for understanding flight performance, atmospheric physics, and has implications for aircraft design and operation.