Subj : Weather Terms (B) Part 4
To : All
From : Daryl Stout
Date : Mon Oct 03 2016 12:06 am
Breakers
Waves that break, displaying white water. Depends on wave steepness and
bottom bathymetry.
Breakup
In hydrologic terms, the time when a river whose surface has been frozen
from bank to bank for a significant portion of its length begins to
change to an open water flow condition. Breakup is signaled by the
breaking of the ice and often associated with ice jams and flooding.
Breakup Date
In hydrologic terms, date on which a body of water is first observed to
be entirely clear of ice and remains clear thereafter.
Breakup Jam
In hydrologic terms, an ice jam that occurs as a result of the
accumulation of broken ice pieces.
Breakup Period
In hydrologic terms, the period of disintegration of an ice cover.
Breezy
15 to 25 mph winds.
BRF
Brief
Bright Band
A distinct feature observed by a radar that denotes the freezing level
of the atmosphere. The term originates from a horizontal band of
enhanced reflectivity that can result when a radar antenna scans
vertically through precipitation. The freezing level in a cloud contains
ice particles that are coated with liquid water. These particles reflect
significantly more radiation (appearing to the radar as large raindrops)
than the portions of the cloud above and below the freezing layer. The
bright band can affect the ability of the NEXRAD algorithms to produce
accurate rainfall estimates at far ranges because the algorithm may
interpret reflectivity from the bright band as an overestimate of
precipitation reaching the surface.
Bright Surge on the Disk (BSD)
In solar-terrestrial terms, a bright gaseous stream (surge) emanating
from the chromosphere.
Bright Surge on the Limb (BSL)
In solar-terrestrial terms, a large gaseous stream (surge) that moves
outward more than 0.15 solar radius above the limb.
Brightness
A basic visual sensation describing the amount of light that appears to
emanate from an object, or more precisely, the luminance of an object.
Brisk
15 to 25 mph winds.
Brisk Wind Advisory
A Small Craft Advisory issued by the National Weather Service for
ice-covered waters.
BRK
Break
BRN
(Bulk Richardson Number) A non-dimensional number relating vertical
stability and vertical shear (generally, stability divided by shear).
High values indicate unstable and/or weakly-sheared environments;
low values indicate weak instability and/or strong vertical shear.
Generally, values in the range of around 50 to 100 suggest environmental
conditions favorable for supercell development.
Broadband
A method of signaling in which multiple signals share the bandwidth of
the transmission by the subdivision of the bandwidth into channels
based on frequency.
Brocken Specter
An optical phenomenon sometimes occurring at high altitudes when the
image of an observer placed between the sun and a cloud is projected on
the cloud as a greatly magnified shadow. The shadow's head is surrounded
by rings of color, called a glory.
Broken Level
A layer of the atmosphere with 5/8 to 7/8 sky cover (cloud cover).
BS
Blowing Snow
BTR
Better
BTWN
Between
Bubble High
A mesoscale area of high pressure, typically associated with cooler air
from the rainy downdraft area of a thunderstorm or a complex of
thunderstorms. A gust front or outflow boundary separates a bubble high
from the surrounding air.
Bubbler Gage
In hydrologic terms, a water stage recording device that is capable of
attaching to a LARC for data automation purposes.
BUFKIT
A software tool used by forecasters to examine the vertical profile and
other aspects of the atmosphere.
Bulk Richardson Number
A non-dimensional (i.e., no units) number relating vertical stability to
vertical shear (generally, stability divided by shear). High values
indicate unstable and/or weakly-sheared environments; low values indicate
weak instability and/or strong vertical shear. Generally, values in the
range of around 50 to 100 suggest environmental conditions favorable for
supercell development.
Buoyancy
The tendency of a body to float or to rise when submerged in a fluid; the
power of a fluid to exert an upward force on a body placed in it.
Burst
In solar-terrestrial terms, a transient enhancement of the solar radio
emission, usually associated with an active region or flare.
Bust
Slang for an inaccurate forecast, especially one where significant
weather (e.g., heavy snowfall) is predicted but does not occur.
Buttress Dam
Buttress dams are comprised of reinforced masonry or stonework built a
gainst concrete. They are usually in the form of flat decks or multiple
arches. They require about 60 percent less concrete than gravity dams,
but the increased form work and reinforcement steel required usually
offset the savings in concrete. Many were built in the 1930's when the
ratio of labor cost to materials was comparatively low. However, this
type of construction is not competitive with other types of dams when
labor costs are high.
BWER
Abbreviation for Bounded Weak Echo Region; a radar signature within a
thunderstorm characterized by a local minimum in radar reflectivity at
low levels which extends upward into, and is surrounded by, higher
reflectivities aloft. This feature is associated with a strong updraft
and is almost always found in the inflow region of a thunderstorm. It
cannot be seen visually.
BYD
Beyond
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