Which atmospheric condition primarily affects visibility during flight?

• A. Altitude
• B. Vapor pressure
• C. Cloud coverage
• D. Humidity

Answer: (C)

Visibility during flight is critically impacted by cloud coverage, particularly due to the presence of clouds and how they obstruct the view of the ground or other aircraft. When clouds are extensive or at low altitudes, they can significantly reduce visibility—creating challenges for pilots during takeoff, landing, and navigation.

While altitude, vapor pressure, and humidity can influence weather conditions and visibility, they do not directly affect visibility as noticeably as cloud coverage does. Altitude may impact the pilot’s overall perspective but isn’t a determinant of visibility under most flying conditions. Vapor pressure is related to the moisture content in the air but doesn’t directly correlate with how far a pilot can see. Humidity, though it contributes to the formation of clouds and fog, is more of a contributing factor rather than the primary condition that obstructs visibility compared to cloud coverage. Thus, cloud coverage stands out as the main atmospheric condition affecting visibility during flight.