Created: 2/23/2005 2:52:15 PM 
By Mark Collins First Coast News
JACKSONVILLE, FL -- Dense sea fog socked in the beaches Wednesday afternoon reducing visibilities below one mile. Light winds and cold Atlantic water temperatures helped to create the thick fog.
This time of year sea fog can become more frequent because water is still very chilly but the air above the ocean can become unusually warm. The 58 degree water has chilled the surface layer of warm air to a point where air condenses out water vapor and forms fog. Fog is a cloud at the surface.
As a given rule the air must be saturated with humidity at 100%. Over the ocean fog can form with humidity as low as 97% due to the salt air enhancing the condensation process.
Cold water combining with warm overlying air is the principle behind the foggy weather around San Francisco and much of the Pacific Northwest.
Here in Jacksonville, dense fog averages four days out of the month in February making it the fourth foggiest month in Jacksonville. November and December are the foggiest with six days. Heavy fog in summer averages once during June and July.
©2009 First Coast News. All rights reserved. This material may not be published, rewritten, or redistributed.
