Temperature
- the degree of hotness or coldness as measured on some definite
temperature scale
Temperature
Gradient - the gradient of the temperature
field; the rate of change of temperature over some distance in a given
direction, usually horizontally or vertically
Temperature
Inversion - a layer in which air temperature
increases with height
Terrestrial
Radiation - the total amount of infrared
radiation which is emitted from the earth's surface or atmosphere
Thermistor
- an electrical resistor making us of a semiconductor whose
resistance varies sharply in a known manner with the temperature
Thermodynamic
Chart (or Thermodynamic Diagram) - a chart containing isopleths
(contours) of pressure, temperature,
moisture, and potential temperature,
all drawn relative to each other such that basic thermodynamic
laws are satisfied (e.g., conservation of energy). Such a chart typically
is used to plot atmospheric soundings, and
to estimate potential changes in temperature, moisture, etc. if air were
displaced vertically from a given level. A thermodynamic chart thus is
a useful tool in diagnosing atmospheric instability.
Thermodynamics
- the relationships between heat
and other properties (such as temperature,
pressure, density,
etc.)
Thermal
Ridge - an axis of relatively high values of temperature
Thermometer
- an instrument for measuring temperature
consisting typically of a glass bulb attached to a fine tube of glass
with a numbered scale and containing a liquid that is sealed in and rises
and falls with changes of temperature
Theta-e
- see equivalent potential
temperature
Theta-e
Ridge - an axis of relatively high values of equivalent
potential temperature. Severe weather and excessive rainfall often
occur near or just upstream from a theta-e
ridge.
Thin
Line - a line of reflectivity
separating air of differing densities. Thin
lines typically are located ahead of a thunderstorm,
but can be associated with cold fronts
and dry lines. The thin line is caused by
backscattering of the radar's pulse off of
a gradient in the index of refraction
of air (i.e, a sharp contrast in air density across a short distance).
3-body
hail spike - see hail spike
Thunder
- the sound that follows a flash of lightning
and is caused by sudden expansion of the air in the path of the electrical
discharge
Thunderstorm
- a local storm produced by a cumulonimbus
cloud, always with lightning and thunder,
and usually accompanied by strong gusts of wind,
heavy rain, and sometimes hail
Tilted
Storm (or Tilted Updraft) - a thunderstorm
or cloud tower which is not purely vertical but instead exhibits a slanted
or tilted character; it is a sign of vertical wind
shear, a favorable condition for severe storm development
Tornado
- a violently rotating column of air protruding from a cumulonimbus
cloud and in contact with the ground; a condensation
funnel does not need to reach to the ground for a tornado to be present
Tornado
Warning - issued by the local National Weather Service office
when a tornado or funnel
cloud has been sighted visually or detected by radar;
the location and direction of movement, if know, are given, and residents
of the warning area should take immediate safety precautions
Tornado
Watch - issued by the Storm Prediction
Center in Norman, OK as a precautionary alert when conditions are
favorable for the development of tornadoes in the
specific area
Total-Totals
Index - a measure of stability
and used as a severe weather forecast tool; equal to the temperature
at 850 mb plus the dew point at 850 mb,
minus twice the temperature at 500 mb. In general, values of less than
50 or greater than 55 are considered weak and strong indicators, respectively,
of potential severe storm development.
Towering
Cumulus - a large cumulus cloud
with great vertical development, usually with a cauliflower-like appearance,
but lacking the characteristic anvil of a cumulonimbus;
same as "towering cu", and abbreviated TCU
Trace
(of Precipitation) - an amount of precipitation
less than 0.005 inches
Trade
Winds - the wind system, occupying most of the tropics, which
are northeasterly in the Northern Hemisphere and southeasterly in the
Southern Hemisphere
Transpiration
- the process by which plants transfer water within to water
vapor in the atmosphere
Triple
Point - the intersection point between two boundaries (dry
line, outflow boundary, cold front,
etc.) OR a point on the gust front
of a supercell, where the warm moist inflow,
the rain-cooled outflow from the forward flank downdraft
and the rear flank downdraft all intersect. This
point is a favored location for thunderstorm
development in the former definition and tornado
development (or redevelopment) in the latter definition.
Tropical
Cyclone - the general term for a large low
pressure system that originates over the tropical oceans; includes
tropical depressions, tropical
storms, and hurricanes
Tropical
Depression - a tropical cyclone
with winds equal to or less than 27 knots
Tropical
Storm - a tropical cyclone with
winds stronger than 27 knots but less than 66 knots
Tropopause
- the upper boundary of the troposphere,
usually characterized by an abrupt change in how the temperature
changes with height; below the tropopause temperature generally decreases
with height; above the tropopause temperature generally increases with
height
Troposphere
- the portion of the atmosphere
which extends outward about 10 to 20 km from the earth's surface, and
in which generally temperature decreases rapidly
with altitude, clouds form, and convection
is active
Trough
- an elongated area of relatively low atmospheric
pressure; the opposite of ridge
True
North - the direction from any point on the earth's surface
toward the geographic North Pole
Turbulence
- irregular atmospheric motion especially when characterized
by up and down currents
TVS
(Tornadic Vortex Signature) - a distinct
feature in the Doppler radar radial
velocity field; it indicates intense, concentrated rotation -- more
so than that of a mesocyclone. Existence
of a TVS strongly increases the probability of tornado
occurrence, but does not guarantee it. A TVS is not a visually
observable feature.
Typhoon
- a hurricane which occurs
in the region of the Philippines or the China Sea
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