Which phenomenon describes moist air being forced up a slope leading to fog formation?

The phenomenon that involves moist air being forced up a slope, which leads to fog formation, is known as upslope fog. This process occurs when air that is saturated or near saturation is pushed upwards along a topographical feature like a hillside or mountain. As the air rises, it expands and cools adiabatically, which can lead to the formation of clouds or fog if the temperature drops to the dew point.

In the case of upslope fog, the moisture content in the air condenses as it rises, contributing to the fog's formation along the slope. This can result in a thick blanket of fog at higher elevations while the lower areas may remain clear.

Understanding upslope fog is essential for pilots and meteorologists, especially in mountainous regions, as it can significantly impact visibility and flight operations.