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Sea Smoke
Wed Feb 25, 2004
Listen in RealAudio 
Looking out over the sea surface on a frigid morning, you might think the waters are
smoldering. No, it's not fire, but rising plumes known as sea smoke. Hi, I'm Bryan Yeaton, and
this is The Weather Notebook.
Sea smoke, a form of advection fog, arises when frigid polar air overruns the relatively warm,
moist air at the water's surface. Because that surface air is much warmer, and therefore
lighter, the air above it rises in distinct, moist thermal plumes. As these plumes rise and
mix with the colder air, they too cool.
When plume temperatures eventually reach their saturation point, the water vapor within them
quickly condenses into small droplets, which make the plumes visible, much like seeing your
breath on a cold day. When these plumes are scattered over the sea surface, they resemble
rising columns of smoke, only without the chimney.
Low wind speeds heighten the likelihood that ascending plumes will remain distinct, rising
vertically in long tendrils that can appear like the swaying arms of inverted
jellyfish.
Along coastal regions, such as the Gulf of Maine, sea smoke frequently arises in autumn and
early winter when an arctic air mass slips off the continent onto the warmer Atlantic waters.
In Arctic and Antarctic waters, sea smoke often forms over small open areas within the sea
ice.
In other instances, sea smoke plumes merge into a denser, yet shallow, fog layer - typically
less than ten feet thick - that can reduce visibility to near zero.
Thanks to our contributing writer, meteorologist Keith Heidorn. Our show is a production of
the Mount Washington Observatory, online at www.mountwashington.org. Funding for The Weather
Notebook comes from The National Science Foundation and Subaru, Driven by What's Insid
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