Which factor is NOT one that determines the physical effects of G forces?

The factor that does not determine the physical effects of G forces is weather conditions. G forces, or gravitational forces, primarily depend on the magnitude of acceleration, the duration of the force application, and the direction in which these forces are applied.

Magnitude refers to the strength of the G force experienced, which can vary based on the rate of change of speed or direction of the aircraft. The greater the acceleration, the higher the G force felt by the pilot or passenger. Duration is crucial as well because the longer the G forces are applied, the more pronounced their effects will be on the body, leading potentially to G-induced Loss Of Consciousness (GLOC) if the forces are extreme and prolonged. Direction is also a critical factor since the orientation of the force (e.g., whether it is sustained horizontally or vertically) influences how the body experiences the forces and the consequent physiological effects.

Weather conditions, however, do not have a direct impact on how G forces act on the body. They may influence flight operations or the environment in which these forces are experienced, but they do not change the fundamental relationship between the magnitude, duration, and direction of the G forces themselves and their physiological effects.