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Glossary of Terms: T
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- Taiga
- See
Boreal Forest.
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- Taku
- Name for a
katabatic type
of cold wind that occurs in Alaska.
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- Talik
- An unfrozen section of ground found above, below,
or within a layer of discontinuous
permafrost.
These layers can also be found beneath water bodies
in a layer of continuous permafrost. A number of
different types of talik have been distinguished:
closed
talik, open
talik, and through
talik.
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- Talus
- An accumulation of angular rock debris from
rockfalls.
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- Talus Slope
- A slope that is composed of
talus.
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- Tarn
- A small mountain lake that occurs inside a
cirque basin.
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- Taxon
- A classification category for a group of organisms.
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-
Taxonomic Classification
- Classification of organisms based on structural
and physiological connections between other species.
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- Tectonic Plate
- An extensive layer of
lithosphere that
moves as a discrete unit on the surface of the Earth's
asthenosphere.
-
- Tectonics
- See
plate tectonics.
-
Telescope
-
an optical instrument that can be
utilized for making distant objects
appear closer. Such a device comes with
a set of lenses whose arrangement
influences the way that the light is
gathered and focused so that the image
visualized by the user is magnified.
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Temperate Deciduous
Forest
- Forested biome found
in the mid-latitudes and dominated by
deciduous vegetation.
-
- Temperate Glacier
- Glacier in
which the ice found
below 10 to 20 meters from its surface is at the
pressure
melting point. One of the three types of
glaciers: cold glacier;
temperate
glacier; and
subpolar
glacier.
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Temperate Rain Forest
- An ecosystem that is dominated by large and very
tall evergreen trees. This biome occurs
along the Pacific Northwest coast of North America
where annual precipitation is high and temperatures
are mild.
-
- Temperature
- Temperature is defined as the measure of the average
speed of atoms and
molecules. The higher the temperature
the faster they move.
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Temperature Inversion
- Situation where a layer of warmer air exists above
the Earth's surface in a normal
atmosphere where
air temperature decreases with altitude. In the warmer
layer of air, temperature increases with altitude.
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- Tephra
- Fragmented rock material
ejected by a volcanic explosion.
Also called pyroclastic
material.
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Terminal Fall Velocity
- Velocity at which a particle being
transported by
wind or water falls out of the moving medium. This
velocity is dependent on the size of the particle.
-
- Terminal Moraine
- Moraine that
marks the maximum advance of a
glacier.
-
- Terminal Velocity
- Maximum speed that can be achieve by a body falling
through a fluid like water or air.
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- Terminus
- End or snout of
a glacier.
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- Terrace
- An elevated surface above the existing level of
a floodplain or
shore that
is created by stream or
ocean
wave
erosion.
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- Tertiary
- Geologic period that occurred roughly 1.6 to 65 million years ago.
During this period, mammals become a dominant species on the planet.
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- Tertiary Consumer
- Organisms that occupy the fourth
trophic
level in the
grazing
food chain. These organisms are
carnivores.
Also known as a
secondary
carnivore.
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- Tetrahedron
- Silicon atom joined
by four oxygen atoms (SiO4). The atomic
properties of this molecule cause
it to develop a unique three dimensional crystal
lattice that is pyramid shaped.
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- Texture
- The relative quantities of the different types
and sizes of mineral particles
in a deposit of sediment.
Also see the related
soil
texture.
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- Thalweg
- Line of deepest water in a
stream
channel as seen from above. Normally
associated with the zone of greatest velocity
in the stream.
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- Thematic Map
- Map that displays the geographical distribution
of one phenomenon or the spatial associations that
occur between a few phenomena. Compare with
reference
map.
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- Thematic Mapper
- Remote sensing device
found on Landsat satellites
that scans images in seven spectral bands from visible
to thermal infrared.
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- Theory
- Proposed explanation for the causal mechanisms
responsible for a phenomenon or a set of facts. Also
see hypothesis.
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Thermal Circulation
- Atmospheric circulation caused by the heating and
cooling of air.
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- Thermal Equator
- Continuous area on the globe that has the highest
surface temperatures because of the presence of the
Intertropical
Convergence Zone.
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- Thermal High
- Area of
high
pressure in
the atmosphere caused by
the area having warmer temperatures relative
to the air around it.
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Thermal Infrared
Radiation
- Form of
electromagnetic
radiation with a wavelength between 3
to 14 micrometers (µm).
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- Thermal Low
- Area of
low pressure in the atmosphere caused by
the area having cooler temperatures relative
to the air around it.
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Thermal Metamorphism
- Is the
metamorphic alteration
of rock because
of intense heat released from processes related to
plate
tectonics.
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- Thermocline
- Boundary in a body of water where the greatest
vertical change in temperature occurs.
This boundary is usually the transition zone between the layer of warm water
near the surface that is mixed and the
cold deep water layer.
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Thermodynamic Equilibrium
- This type of
equilibrium describes a condition in a
system where the distribution of mass and energy moves towards
maximum entropy.
-
- Thermodynamic Laws
- Laws that describe the physical processes, relationships,
and phenomena associated with
heat.
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- Thermokarst
- Landscape dominated by depressions, pits, and caves
that is created by the thawing of ground ice in high
latitude locations. Resembles
karst landscape
but is not created by
chemical
weathering.
-
- Thermometer
- Device used to measure
temperature.
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- Thermosphere
- Atmospheric layer above the
mesosphere (above
80 kilometers) characterized by air temperatures
rising rapidly with height. The thermosphere is the
hottest layer in the atmosphere. In the thermosphere,
gamma,
X-ray,
and specific wavelengths of
ultraviolet radiation are
absorbed by
certain gases in the atmosphere. The absorbed radiation
is then converted into
heat
energy. Temperatures in this layer can be
greater than 1200° Celsius.
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-
Third
Law of Thermodynamics
- This law states if all the thermal
motion of
molecules (kinetic
energy) could be removed, a state called
absolute
zero would result and all energy would
be randomly distributed.
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- Threatened Species
- Species that is still plentiful in its natural
range but is likely to become
endangered because
of declining population numbers.
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- Threshold
- The level of
magnitude of
a system process
at which sudden or rapid change occurs.
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- Threshold Velocity
- Velocity required
to cause entrainment in
the erosional agents
of wind, water or ice. Threshold velocity is usually
higher than the velocity required for
transport because
factors like particle cohesion. Also see
critical
entrainment velocity.
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- Throughfall
- Describes the process of
precipitation passing
through the plant canopy. This process is controlled
by factors like: plant leaf and stem density, type
of the precipitation, intensity of the precipitation
and duration of the precipitation event. The amount
of precipitation passing through varies greatly with
vegetation type.
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- Throughflow
- The roughly horizontal flow of water through soil
or regolith.
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- Through Talik
- Is a form of localized unfrozen ground (talik)
in an area of permafrost.
It is open to the ground surface and to an area of
unfrozen ground beneath it. Permafrost encases it
along the sides.
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- Thrust Fault
- A geologic
fault where
the hanging wall is
forced over the foot
wall.
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- Thunder
- Sound created when
lightning causes
the rapid expansion of atmospheric gases along its
strike path.
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- Thunderstorm
- A storm several kilometers in diameter created
by the rapid lifting of moist warm air which creates
a cumulonimbus cloud.
Thunderstorms can have the following severe weather
associated with them: strong winds;
hail;
lightning;
tornadoes;
thunder;
and heavy rain.
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- Tidal Current
- Regional scale
ocean
current that is created the
tidal rise
and fall of the ocean surface.
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- Tidal Period
- Time it takes for one tidal cycle.
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- Tidal Zone
- Area along the
coastline that
is influence by the rise and fall of
tides.
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- Tide
- Cyclical rise and fall of the surface of the
oceans.
Caused by the gravitational attraction
of the Sun and moon on the Earth.
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- Till
- Heterogeneous
sediment
deposited directly
by a glacier.
The particles within this deposit have not been size
sorted by the action of wind or water.
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- Till Plain
- Extensive flat plain of
till that
forms when a sheet of ice becomes detached from the
main body of the glacier and
melts in place depositing the sediments it carried.
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- Time
- Measurable period in which cause and effect occurs
and systems function.
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- TIROS (Television
and Infrared Observation Satellite)
- Series of meteorological satellites launched by
the United States starting in 1960. The main purpose
behind these satellites was to use a variety of
remote
sensing devices for weather forecasting.
TIROS program was very successful, providing the
first accurate weather forecasts based on data gathered
from space. TIROS began continuous monitoring of
the Earth's weather in 1962.
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- Tissue
- A group of similar
cells that
are organized into a structure with a specific purpose.
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Tolerance Model of
Succession
- This model of
succession suggests
that the change in plant
species dominance
over time is caused by
competition for
resources.
Later species are able to tolerate lower resource
levels due to competition and can grow to maturity
in the presence of early species, eventually out
competing them.
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- Tolerance Range
- Limits of tolerance a species has to an
abiotic factor
or condition in the environment.
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- Tombolo
- A coastal feature that forms when a belt
sand and/or
gravel is
deposited between an island and the
mainland. This feature is above sea-level for most
of the time.
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- Topographic Map
- Map that
displays topography through
the use of elevation contour lines.
Base elevation on these maps is usually
sea-level.
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Topographic Profile
- A two-dimensional diagram that describes the landscape
in vertical cross-section.
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- Topography
- The relief exhibited by a surface.
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- Topset Bed
- Horizontal
deltaic deposit
composed of coarse alluvial
sediment.
Represents current or past surface of the delta.
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- Tornado
- A vortex of
rapidly moving air associated with some severe
thunderstorms.
Winds within the tornado funnel may exceed 500 kilometers
per hour.
-
- Tornado Alley
- Region in North America which receives a extraordinary
high number of tornadoes.
This region stretches from central Texas to Illinois
and Indiana.
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- Tornado Warning
- A warning issued to the public that a
tornado has
been observed by an individual in a specified region.
This warning can also be issued if meteorological
information indicates a high probability that a tornado
will develop in a specified region.
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- Tornado Watch
- A forecast issued to the public that a
tornado may
occur in a specified region.
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- Total Column Ozone
- A measurement of
ozone concentration
in the atmosphere.
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- Traction
- Erosional movement
of particles by rolling, sliding and shuffling along
the eroded surface. Occurs in all erosional mediums
(air, water, and ice).
-
- Trade Winds
- Surface winds that generally dominate air flow
in the tropics. These winds blow from about 30° North
and South latitude (subtropical
high pressure zone) to the equator (intertropical
convergence zone). Trade winds in the Northern
Hemisphere have northeast to southwest direction
and are referred to as the Northeast
Trades. Southern Hemisphere trade
winds have southeast to northwest direction but are
called the Southeast
Trades.
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- Transform Fault
- Massive
strike-slip
fault continental in size. Examples of
such faults occur
along tectonic
plate boundaries and at the
mid-oceanic
ridge.
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- Transparency
- The ability of a medium to allow light to pass
through it.
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- Transpiration
- Transpiration is the process of water loss from
plants through stomata.
Stomata are
small openings found on the underside of leaves that
are connected to vascular plant tissues. Some dry
environment plants do have the ability to open and
close their stomata. Transpiration is a passive process
largely controlled by the humidity of the atmospheric
and the moisture content of the soil. Of the transpired
water passing through a plant only 1% is used in
the growth process. Transpiration also transports
nutrients from
the soil into the roots and carries them to the various
cells of the plant.
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- Transport
- One of three distinct processes involved in
erosion.
It is the movement of eroded material in the medium
of air, water or ice.
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- Tree
- A large woody plant that has a trunk which supports
branches and leaves.
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- Triassic
- Geologic period that occurred roughly 208 to 245 million years ago.
During this period, the first dinosaurs appeared.
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- Tributary
- A smaller branching
stream
channel that flows into a main stream
channel. Opposite of
distributary.
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- Trophic Level
- Level of organization in the
grazing
food chain.
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Trophic Pyramid
- A graphic model describing the distribution of
energy, biomass, or
some other measurable quantity between the different
trophic levels found in an
ecosystem.
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- Tropical Cyclone
- Another name for
hurricane.
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Tropical Depression
- An organized group of
thunderstorms often
found over a tropical ocean that generates a cyclonic
flow of between 37 and 63 kilometers per hour. Can
develop into a hurricane.
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Tropical Disturbance
- An organized group of
thunderstorms often
found over a tropical ocean that generates a slight
cyclonic flow of less than 37 kilometers per hour.
Can develop into a hurricane.
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- Tropical Savanna
- See savanna.
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- Tropical Storm
- An organized group of
thunderstorms often
found over a tropical ocean that generates a cyclonic
flow of between 64 and 118 kilometers per hour. Often
develops into a hurricane.
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Tropical Rainforest
- Forested biome found
near the equator and dominated by
evergreen vegetation.
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- Tropic of Cancer
- Latitude of 23.5° North. Northern limit of
the Sun's declination.
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Tropic of Capricorn
- Latitude of 23.5° South. Southern limit of
the Sun's declination.
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- Tropopause
- The tropopause is a relatively thin
atmospheric transition
layer found between the
troposphere and
the stratosphere.
The height of this layer varies from 8 to 16 kilometers
above the Earth's surface.
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- Troposphere
- Layer in the
atmosphere found
from the surface to a height of between 8 to 16 kilometers
of altitude (average height 11 kilometers). The troposphere
is thinnest at poles and gradually increases in thickness
as one approaches the equator. This atmospheric layer
contains about 80% of the total mass of the atmosphere.
It is also the layer where the majority of our planet's
weather occurs. Maximum air temperature occurs near
the Earth's surface in this layer. With increasing
altitude air temperature drops uniformly with increasing
height at an average rate
of 6.5° Celsius per 1000 meters (commonly called
the Environmental
Lapse Rate), until an average temperature
of -56.5° Celsius is reached at the top of the
troposphere.
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- Trough
- An elongated area of
low
pressure in the atmosphere.
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- True North
- Direction of the
North
Pole from an observer on the Earth.
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- True South
- Direction of the
South
Pole from an observer on the Earth.
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- Tsunami
- Large ocean
wave created from an
earthquake or
volcanic eruption.
Open ocean wave height may be as high as 1 meter.
When entering shallow coastal waters, land configuration
can amplify waves to heights of over 15 meters.
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- Tundra
- High latitude
biome dominated
by a few species of dwarf shrubs,
a few grasses,
sedges, lichens,
and mosses.
Productivity is
low in this biome because of the extremes of climate.
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- Turbulent Flow
- Movement of water within a
stream that
occurs as discrete eddies and
vortices.
Turbulent flow is caused by channel topography and
friction.
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Two-Tailed Statistical
Test
- Is an
inferential
statistical test where the values for
which one can reject the
null hypothesis are located either
side of the center of the probability distribution.
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- Typhoon
- Another name for
hurricane.
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Citation: Pidwirny,
M. (2006). "Glossary of Terms: T". Fundamentals of Physical Geography,
2nd Edition. Date
Viewed. http://www.physicalgeography.net/physgeoglos/t.html
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