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Photographer's Description:
Within a thick bank of fog, the WSR-88D radar is barely visible from just 270 feet away. The dim sun, low on the horizon, attempts to shine through.
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Photographer |
Andy Hatzos, NWS
Wilmington |
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Date taken |
December 6, 2007 |
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Location |
Wilmington, OH (Clinton County)
map |
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Event |
Radiation fog |
Additional notes
This photo shows
radiation fog, which usually develops late at night and early
morning when the ground radiates heat into the atmosphere (hence the
name), causing the air near the surface to cool off rapidly. If
enough moisture is in place, the temperature will eventually drop to
match the
dewpoint temperature, causing moisture in the air to condense
and form fog. Clear skies and calm winds are usually needed for
this to happen. Click the link below to see atmospheric
conditions which favor radiation fog.
Since radiation fog is driven by the temperature near the ground, it is
usually shallow. It can range from about a thousand feet in depth
to just a few feet off the ground.
Valleys are particularly prone to this type of fog since they are
protected from the wind and cool off faster.
On this particular day, the temperature was well below freezing which
caused the fog to deposit ice crystals on objects (see link below).
This phenomenon is referred to as
freezing fog.
Safety Note:
Radiation fog can be very localized which presents a hazard
to drivers. While prevailing visibilities may be nearly clear,
they may drop to near zero in a matter of seconds when a car enters an
area of dense fog. This may cause a driver to brake hard and
increase the risk of getting rear ended (a common cause of fog-related
accidents). For this reason, it's always important to keep a safe
distance between you and the car in front of you when radiation fog is
present, even when visibility is clear.
Related NWS Product:
Dense Fog Advisory,
Freezing Fog Advisory |
See ice which was
deposited on objects
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See atmospheric conditions
which favor radiation fog
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www.nws.noaa.gov 
