Which environmental factor can impede vision while flying?

Fog and haze can significantly impede vision while flying. These conditions create a reduction in visibility due to moisture or particulate matter suspended in the air, allowing less light to penetrate and making it difficult for pilots to see other aircraft, landmarks, or the runway during takeoff and landing. Fog is particularly dense and often leads to very low visibility conditions, which can pose serious safety risks.

Clear skies typically allow for optimal visibility, while high altitude does not inherently obstruct vision, although it may present other challenges. Calm winds are generally beneficial to flying conditions and do not directly impact visibility. Hence, fog and haze represent significant barriers to safe flying due to their effect on visual perception.