Evolution and Dissipation

The lifetime of a sea fog event will depend mostly on diurnal effects, but also mesoscale processes that change the stability of the boundary layer. Radiational effects from daytime to nighttime environments will favor different types of sea fogs. For instance, during the daytime, conditions are more favorable for steam sea fog events due to cooler air masses drifting across warmer sea surfaces in a generally unstable boundary layer. Steam sea fogs can still occur during the evening hours as well. Nighttime conditions will favor advected sea fog formations because warm, moist air will advect over colder waters and cool the atmosphere in a stable environment. The cooling of the lowest part of the boundary layer will initialize condensation.

<Wu, B.G., Wang. Z.Y., Xie, Y.Y., 2012. Analysis of air flow and turbulent fluxes features of night fog. Applied Mechanics and Materials 137, 298.>

Figure depicting the diurnal effect of a sea fog event. The x-axis shows the humidity and the y-axis shows the time of day. The warming over the land increases humidity levels. When the sun sets below the horizon, the moisture content still remains in the stable boundary layer. As the atmosphere cools over night, the water vapor in the atmosphere begins to condense. The sea fog event occurs just before the sun rises the next day, when the atmosphere is most stable. The sun rises in the morning hours, causing the sea fog to dissipate.

The stability of the boundary layer is crucial for the development and lifetime of sea fog events. Certain parameters of outside environmental conditions will determine if the boundary layer is unstable or stable, neglecting diurnal variations. Coastal regions can develop land or sea breezes that may disrupt or amplify sea fog formation. Sea surface temperatures are crucial for determining the rate in which the boundary layer cools or warms. These temperatures will change depending on global location of the coastal region, and diurnal-seasonal cycle variations. Sea fog events dissipate once the environment changes and disrupts the stability of the boundary layer.