What causes advection fog to persist?

Advection fog is primarily caused by the horizontal movement of warm, moist air over a cooler surface, which results in the cooling of that air to its dew point, leading to fog formation. To understand why wind direction changes contribute to the persistence of advection fog, it’s important to recognize that sustained wind from a consistent direction can continually supply moist air to an area. This consistent flow maintains the temperature and humidity conditions necessary for the fog to persist.

If wind direction changes, it might introduce drier air or unsettled atmospheric conditions, which could lead to the dispersal of the fog. Thus, stable wind patterns support prolonged fog conditions by ensuring the inflow of moist air necessary for the fog to maintain its formation over time. Hence, the persistence of advection fog is closely tied to the stability and direction of the wind flow bringing in moisture, which keeps the air saturated and the fog intact.