Wall
Cloud - a generally rain-free region of rotating clouds which
extends beneath a severe thunderstorm
and from which a funnel cloud may form
Warm
Advection - the transport of warm air into an area by horizontal
winds
Warm
Cloud - a cloud comprised of only
water droplets (i.e., no ice particles)
Warm
Front - the advancing edge of a warm air mass
Warning
- a product issued by the local National Weather Service office
when a particular weather hazard is either imminent or has been reported.
A warning indicates the need to take action to protect life and property.
The type of hazard is reflected in the type of warning (e.g., tornado
warning, blizzard warning).
Watch
- a National Weather Service product indicating that conditions
are favorable for the occurrence of a particular hazard. A watch is a
recommendation for planning, preparation, and increased awareness.
Water
Vapor - water in a gaseous (vapor)
form
Waterspout
- a funnel-shaped or tubular column of rotating cloud-filled
wind usually extending from the underside of a cumulus
or cumulonimbus cloud down to the surface
of an ocean or lake
Watt
(W) - the derived unit for power. Named for James Watt
(1736-1819), a Scottish engineer. 1 watt is equal to 1 joule
per second
Wavelength
- the distance between two corresponding points of two consecutive
waves (e.g., crest to crest or trough to trough).
Weather
- the state of the atmosphere with respect to heat or cold,
wetness or dryness, calm or storm, clearness or cloudiness
Weather
Map - a map or chart showing the principal meteorological elements
at a given time and over an extended region
Weather
Radar - any radar which can be used
to detect precipitation or clouds
WER
(Weak Echo Region) -
a radar term for a region of relatively
weak reflectivity at low levels on the
inflow side of a thunderstorm echo,
topped by stronger reflectivity in the form of an echo overhang
directly above it. The WER is a sign of a strong updraft
on the inflow side of a storm, within which precipitation
is held aloft. When the area of low reflectivity extends upward into,
and is surrounded by, the higher reflectivity aloft, it becomes a BWER.
Wet
Bulb Temperature - The lowest temperature
that can be obtained by evaporating water into the air at constant pressure.
The name comes from the technique of putting a wet cloth over the bulb
of a mercury thermometer and then blowing air over the cloth until the
water evaporates. Since evaporation requires heat, the thermometer will
cool to a lower temperature than a thermometer with a dry bulb at the
same time and place. Wet bulb temperatures can be used along with the
dry bulb temperature to calculate dew point
or relative humidity.
Wet
Microburst - A microburst accompanied
by heavy precipitation at the surface
Whitebody
- a hypothetical body whose surface absorbs no electromagnetic
radiation of any wavelength; opposite of a blackbody.
Wideband
Data - the high-resolution, base products (reflectivity,
radial velocity, and spectrum
width) in polar-coordinate form that are transmitted from the RDA
to the RPG for further processing
Wien's
Displacement Law - the radiation law that states that the wavelength
of maximum radiation intensity for a blackbody
is inversely proportional to the absolute
temperature of the radiating blackbody
Wind
- a natural movement of air at a velocity
relative to the surface of the earth
Wind-Chill
Factor - a still-air temperature
that would have the same cooling effect on exposed human flesh as a given
combination of temperature and wind speed
Wind
Direction - the direction from which the wind
is blowing
Wind
Shear - the local variation of the wind
speed and/or direction in a given direction. Shear usually refers to vertical
wind shear (i.e., the change in wind with height) but the term also is
used in Doppler radar meteorology
to describe changes in radial velocity
over short horizontal distances. Moderate to strong wind shear is required
for supercell evelopment. See Bulk
Richardson Number.
Wind
Speed - the ratio of the distance traveled by the air to the
time taken to cover the distance
Wind
Vane - an instrument used to indicate wind direction
Windward
Side - the side of an object facing the direction from which
the wind is blowing
Winter
- the period extending from the winter
solstice, about 22 December, to the vernal
equinox, about 21 March
Winter
Solstice - the solstice when
the sun is lowest in the sky; the first day of winter
Work
- an energy form arising from the
displacement of an object by a force; the conversion
of potential energy to kinetic energy.
WSR-57,
WSR-74 - NWS Weather Surveillance Radar
units, replaced by WSR-88D units
WSR-88D
(Weather Surveillance Radar - 1988 Doppler)
- a NEXRAD unit
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