At what altitude above the surface does fog typically begin to form?

Fog typically forms when the air near the surface cools to the dew point, which often occurs around 50 feet above the ground. At this altitude, conditions such as temperature, humidity, and the presence of stable air can come together to create fog. The cooling of the air reduces its capacity to hold moisture, leading to condensation and the development of fog. This phenomenon is particularly common in low-lying areas and can significantly impact visibility.

Understanding the altitude at which fog typically forms is essential for safe flight operations, especially for unmanned aircraft, which can be affected by low visibility. Recognizing these conditions helps ensure compliance with safety regulations and operational guidelines.