A fogbow, according to NOAA, is a
rainbow that has a white band that appears in fog, and is fringed with red on
the outside and blue on the inside. I think you’d know it if you’d seen one.
NOAA seems to be well informed about
fog in general. Here are some other terms they use, and their descriptions:
Ø Advection fog — Fog that results
from the advection of moist air over a cold surface, and the cooling of the air
to its dew point. The most common type of fog in coastal regions.
Ø Dense fog — Fog in which visibility
is less than one-quarter mile.
Ø Fog — Water that has condensed
close to ground level, producing a cloud of very small droplets that reduces
visibility to less than 3,300 feet. (Why 3,300 feet, you ask. Sorry, I just don’t
NOAA.)
Ø Ground fog — Fog that’s less than
20 feet deep. It’s produced by the cooling of the lower atmosphere coming into
contact with the ground (or, presumably, cold water). It’s also called
radiation fog.
Ø Ice fog — It’s composed of minute
ice crystals suspended in the air, or water droplets at temperatures below 0°C,
down at surface level and restricting horizontal visibility. It’s also known as
freezing fog, and usually occurs at minus 20°F and below.
Ø Mist — Mist is very much like fog,
being composed of tiny water droplets suspended in the air. The difference is
that it doesn’t reduce visibility as much as fog does.
Ø Overrunning — This is a combination
of low clouds, fog, and steady light rain. It comes about when a comparatively
warm air mass moves up and over colder, denser air on the surface.
Ø Shallow fog — Fog in which
visibility is 5/8 of a mile or more, viewed from 6 feet above ground (or sea)
level.
Ø Steam fog — That is what happens
when very cold air drifts over comparatively warm water. It’s also known as sea
smoke.
Today’s
Thought
The
fog comes
on
little cat feet.
It
sits looking
over
the harbor and city
on
silent haunches
and
then, moves on.
— Carl Sandburg, Fog
Tailpiece
As I was laying on the green,
A small English book I seen.
Carlyle’s Essay on Burns was the name of the edition,
So I left it laying in exactly the
same position.
(Drop by every Monday, Wednesday,
Friday for another Mainly about Boats
column.)
4 comments:
I think it's 3,300 ft because that's the equivalent of 1,000 metres (1Km in the SI system), which itself is the nearest SI equivalence to half-a-cable in proper nautical measurement.
Fog be damned. Full speed ahead.
Patrick, that's probably the answer. Sounds reasonable to me.
Cheers,
John V.
Hudson, I seem to have heard that before somewhere!
Can't remember where.
John V.
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