GALE
On the Beaufort Wind Scale, a wind with speeds from 28 to 55 knots (32 to 63 miles per
hour). For marine interests, it can be categorized as a moderate gale
(28 to 33 knots), a fresh gale (34 to 40 knots), a strong gale (41 to
47 knots), or a whole gale (48 to 55 knots). In 1964, the World Meteorological
Organization defined the categories as near gale (28 to 33 knots), gale
(34 to 40 knots), strong gale (41 to 47 knots), and storm (48 to 55
knots).
GALE WARNING
A warning for marine interests for
impending winds from 28 to 47 knots
(32 to 54 miles per hour).
GEOPHYSICS
The study of the physics or nature of the Earth and its environment.
It deals with the composition and physical phenomena of the earth and
its liquid and gaseous envelopes. Areas of studies include the atmospheric
sciences and meteorology,
geology, seismology, and volcanology,
and oceanography and related marine sciences, such as hydrology. By
extension, it often includes astronomy
and the related astro-sciences.
GEOSPHERE
Considered the
solid portions of the earth, including the hydrosphere and the lithosphere,
as opposed to the atmosphere,
which lies above it. At their conjunction is the biosphere.
GEOSTATIONARY SATELLITE
An orbiting weather
satellite that maintains the same position over the equator during the
earth's rotation. Also known as GOES, an acronym for Geostationary Operational
Environmental Satellite. Related terms: polar-orbiting
satellite Visit WALTER
Satellite Tutorial web-page
GEOSTROPHIC WIND A steady horizontal motion of
air along straight, parallel isobars
or contours in an unchanging pressure or contour field. It is assumed
that there is no friction, that the flow is straight with no curvature
and there is no divergence or convergence with no vertical acceleration.
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GLACIER WINDS
Air flow that descends from glaciers, occasionally at a high rate of speed. Caused
by the temperature difference between the air in contact with the glacier
and the air at the same altitude,
it reaches maximum intensity in the early afternoon. Related term: katabatic
wind
GLAZE
A smooth clear icy coating
of supercooled water droplets that spread out and freeze onto objects
on contact. A storm that produces the accretion of glaze is called an
ice storm. Related term: clear
ice
GRADIENT WIND
A steady horizontal air motion along curved parallel isobars
or contours in an unchanging pressure
or contour field, assuming there is no friction and no divergence
or convergence.
GRAUPEL
A form of frozen precipitation consisting
of snowflakes or ice crystals
and supercooled water droplets frozen together. Related term: snow
pellets
GRAVITATION
The mutual attraction between two masses of matter. The rotation of the earth and
the atmosphere modifies this attraction to produce the field of gravity.
GRAVITY
The force of attraction
of the earth on an object. The direction is downward relative to the
earth, and it decreases with elevation or altitude
away from the earth's surface.
GREEN FLASH
A brilliant green coloration of the upper edge of the sun, occasionally seen as
the sun's apparent disk is about to set below a clear horizon.
GREENHOUSE EFFECT
The overall warming of the earth's lower atmosphere primarily due
to carbon dioxide and water
vapor which permit the sun's rays to heat the earth, but then restrict
some heat-energy from escaping back into space.
GREENWICH MEAN TIME (GMT)
The name of the twenty-four hour time scale which is used throughout
the scientific and military communities. Standard Time begins at Greenwich,
England, home of the Royal Observatory which first utilized this method
of world time. This is also the Prime Meridian of Longitude. The globe
is divided into twenty-four (24) time zones of 15 degrees of arc, or
one hour in time apart. To the east of this meridian, time zones are
number from 1 to 12 and prefixed with a minus (-), indicting the number
of hours to be subtracted to obtain Greenwich Time (GMT). To the west,
the time zones are also numbered 1 through 12, but are prefixed with
a plus (+), indicating the number of hours to be added to obtain GMT.
Related terms: Universal
Time Coordinate(UTC) and Zulu (Z)
GROUND CLUTTER
A pattern of radar echoes reflecting off fixed ground targets such as buildings
or hills near the radar. This may
hide or confuse the proper return echo
signifying actual precipitation.
GROUND FOG
Fog created when radiational cooling at the earth's surface lowers the temperature
of the air near the ground to or below its initial dew
point. Primarily takes place at night or early morning. Related
term: radiation fog
GROWING SEASON
Considered the period of the year during which the temperature of cultivated vegetation
remains sufficiently high enough to allow plant growth. Usually considered
the time period between the last killing frost
in the spring and the first killing frost of the autumn. The frost-free
growing season is between the first and last occurrence of 32 degrees F temperatures
in spring and autumn.
GULF STREAM
The warm, well-defined, swift, relatively
narrow ocean current which exists off the east coast of the United States,
beginning near Cape Hatteras. The term also applies to the oceanic system
of currents that dominate the western and northern Atlantic Ocean: the
Florida current, which flows through the Florida Straits between the
Florida Keys and Cuba and northwards; the Gulf Stream, which begins
around Cape Hatteras and flows northeasterly off the continental slope
into the North Atlantic; and the North Atlantic current, which begins
around the Grand Banks off Newfoundland and continues east-northeastwards
towards the British Isles.
GULLY WASHER
A heavy rain shower that occurs suddenly,
possibly creating a flash flood.
GUST
A sudden significant increase in or rapid fluctuations of wind
speed. Peak wind must reach at least 16 knots (18 miles per hour)
and the variation between peaks and lulls is at least 10 knots (11.5
miles per hour). The duration is usually less twenty seconds.
GUST FRONT
The leading edge of the cool, gusty surface winds produced by thunderstorm downdrafts.
Sometimes confused with an outflow boundary. Related term: first
gust
GUSTNADO
A weak, and usually short-lived, tornado that forms
along the gust front of a thunderstorm, appearing as a temporary dust whirl
or debris cloud.
