Which temperature is defined as the temperature of still air?

The temperature defined as the temperature of still air is the Standard Ambient Temperature (SAT). SAT is the temperature measured in air that is not moving, which allows it to represent the true thermal state of the environment without the influence of wind or other factors. This is particularly important in aviation, as it provides a baseline for various calculations related to performance and engine efficiency.

In aviation, other terms like OAT (Outside Air Temperature) are used but can be influenced by wind and other atmospheric conditions. Therefore, SAT serves as a crucial point of reference when considering how aircraft operate in different thermal environments. The distinction of SAT being measured in still air makes it essential for understanding how temperature affects lift, drag, and engine operations, thereby playing a significant role in flight safety and efficiency.