Tipping-Bucket Rain GageA precipitation gage where collected water is funneled into a two compartment bucket; 0.01, 0.
Tissue(TISH-oo) A group or layer of cells that work together to perform a specific function.
Tissue cultureThe in vitro culture of cell s, tissue s or organ s in a nutrient medium under sterile conditions.
titre1. The concentration of infectious virus particles present in a suspension. 2. A measure of antibody concentration, given by the highest dilution of the…
Toe (toe of dam)The point of intersection between the bottom of a slope or the upstream or downstream face of a dam and the natural ground, for example, the upstream or…
Toe Drain (or Outfall)A drain which carries seepage away from the dam and can allow seepage quantities to be measured.
Toe drain(s)Open-jointed tile or perforated pipe located at the toe of the dam used in conjunction with horizontal drainage blankets to collect seepage from the…
Toe of DamThe junction of the downstream face with the ground surface. See also, "Heel of Dam".
Toe weightAdditional material placed at the toe of an embankment dam to increase its stability.
ToleranceA condition in which higher doses of a drug are required to produce the same effect achieved during initial use; often associated with physical dependence.
Tolerance inductionThe "education" process that T cells undergo to discriminate between self and foreign proteins. This process takes place primarily in the thymus.
Tolling agreementAn agreement whereby a party moves fuel to a power generator and receives kilowatt hours (kWh) in return for pre-established fees.
tonoplastThe cytoplasmic membrane bordering the vacuole of plant cells. It plays a prominent role in regulating the osmotic pressure exerted by the cell sap.
Top of active conservation capacityThe reservoir water surface elevation at the top of the capacity allocated to the storage of water for conservation purposes only. See reservoir.
Top of dead capacityThe lowest elevation in the reservoir from which water can be drawn by gravity.
Top of exclusive flood control capacityThe reservoir water surface elevation at the top of the reservoir capacity allocated to exclusive use for the regulation of flood inflows to reduce damage…
Top of inactive capacityThe reservoir water surface elevation below which the reservoir will not be evacuated under normal conditions.
Top of joint use capacityThe reservoir water surface elevation at the top of the reservoir capacity allocated to joint use, i.e., flood control and conservation purposes.
Topographic mapA map indicating surface elevation and slope. U.S. Geological Survey quadrangle series maps showing the shape of the earth's surface by contours.
TopographyThe shape of the Earth's surface; the relative position and elevations of natural and human-made features of an area.
Topping and back pressure turbinesTurbines which operate at exhaust pressure considerably higher than atmospheric (noncondensing turbines).
Topping cycleA means to increase the thermal efficiency of a steam electric generating system by increasing temperatures and interposing a device, such as a gas…
TopsoilThe topmost layer of soil, usually containing organic matter. Usually refers to soil containing humus which is capable of supporting plant growth.
TornadoA violently rotating column of air, usually pendant to a cumulonimbus, with circulation reaching the ground.
Tornado FamilyA series of tornadoes produced by a single supercell, resulting in damage path segments along the same general line.
Tornado Vortex SignatureAn image of a tornado on the Doppler radar screen that shows up as a small region of rapidly changing wind speeds inside a mesocyclone.
Tornado WarningThis is issued when a tornado is indicated by the WSR-88D radar or sighted by spotters; therefore, people in the affected area should seek safe shelter…
Tornado WatchThis is issued by the National Weather Service when conditions are favorable for the development of tornadoes in and close to the watch area.
Torque (Motor)The turning or twisting force generated by an electrical motor in order for it to operate.
Total capacityThe reservoir capacity below the highest of the elevations representing either the top of exclusive flood control capacity, the top of joint use capacity…
total carbonThe total concentration of carbon in all its organic and non-organic forms.
total cloud waterThe total concentration (mass/vol) of ice and liquid water particles in a cloud.
Total dissolved solids (TDS)(TDS)The dry weight of dissolved material, organic and inorganic, contained in water. The term is used to reflect salinity.
Total dynamic head (TDH)When a pump is lifting or pumping water, the vertical distance from the elevation of the energy grade line on the suction side of the pump to the…
Total Gross Reservoir CapacityThe total amount of storage capacity available in a reservoir for all purposes from the streambed to the normal water or normal water or normal pool…
Total Harmonic DistortionThe measure of closeness in shape between a waveform and it's fundamental component.
Total HeatThe sum of the sensible and latent heat in a substance or fluid above a base point, usually 32 degrees Fahrenheit.
Total Incident RadiationThe total radiation incident on a specific surface area over a time interval.
Total Internal ReflectionThe trapping of light by refraction and reflection at critical angles inside a semiconductor device so that it cannot escape the device and must be…
total ligninThe sum of the acid soluble lignin and acid insoluble lignin fractions.
Total maximum daily loads (TMDL)Estimates of the amount of specific pollutants that a body of water can safely take without threatening beneficial uses.
Total Solar IrradianceThe total amount of radiant energy from the Sun that falls on a surface in a given amount of time.
total solidsThe amount of solids remaining after all volatile matter has been removed from a biomass sample by heating at 105°C to constant weight.
Total suspended particulates (TSP)(TSP)The quantity of solid particles in a gas or exhaust stream. Any finely divided material (solid or liquid) that is airborne with a diameter smaller than a…
Total-Totals IndexA stability index and 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.
Totalizer (integrator)A device or meter that continuously measures and calculates (adds) total flow.
totipotencyThe ability of a cell or tissue to be induced to regenerate into a complete organism.
TotipotentHaving to do with cells that are able to develop into any type of cell found in the body.
Totipotent stem cellsStem cells that can give rise to all cell types that are found in an embryo, fetus, or developed organism, including the embryonic components of the…
Towering CumulusA large cumulus cloud with great vertical development, usually with a cauliflower-like appearance, but lacking the characteristic anvil of a Cb.
Toxic substancesA chemical or mixture of chemicals that presents a high risk of injury to human health or to the environment.
Toxic Substances Control Act (TSCA)(TSCA)The Toxic Substances Control Act (TSCA), passed in 1976, requires tests of chemicals that may harm human health or the environment; reviews of new…
toxicity(tok-SIH-sih-tee) The extent to which something is poisonous or harmful.
ToxicogenomicsThe study of how genomes respond to environmental stressors or toxicants. Combines genome-wide mRNA expression profiling with protein expression patterns…
toxicsAs defined in the 1990 Clean Air Act Amendments, toxics include benzene, 1,3 butadiene, formaldehyde, acetaldehyde, and polycyclic organic matter.
toxin(TOK-sin) A poison produced by certain animals, plants, or bacteria.
TPC(Tropical Prediction Center) - An NCEP center which produces marine offshore and high seas forecasts south of 30N in the Eastern Pacific, Gulf of Mexico…
TraceA hydrograph or similar plot for an extended-range time horizon showing one of many scenarios generated through an ensemble forecast process.
Trace GasAny one of the less common gases found in the Earth's atmosphere. Nitrogen, oxygen, and argon make up more than 99 percent of the Earth's atmosphere.
tracerA substance (such as a radioisotope) used in imaging procedures.
tracheidAn elongated, tapering xylem cell, with lignified pitted walls, adapted for solute conduction and physical support.
TrackEach of the series of concentric rings contained on a hard drive platter.
Tracking arrayA PV panel array that follows the path of the sun to maximize the solar radiation incident on the PV surface.
Tracking Solar ArrayA solar energy array that follows the path of the sun to maximize the solar radiation incident on the PV surface.
Tractor gateRectangular gate supported and sealed similar to the paradox gate. Main difference is that the leaf is raised and lowered by a cable hoist, and operated…
Trade WindsPersistent tropical winds that blow from the subtropical high pressure centers towards the equatorial low.
Traditional breedingModification of plants and animals through selective breeding. Practices used in traditional plant breeding may include aspects of biotechnology such as…
Traditional cultural propertyA property that is eligible for inclusion in the National Register of Historic Places because of its association with cultural practices or beliefs of a…
Traditional cultural property (TCP)A site or resource that is eligible for inclusion in the National Register of Historic Places because of its association with cultural practices or…
Traditional NeighborhoodsTraditional neighborhood development emphasizes two broad goals: to reduce the destruction of habitat and natural resources, and to reduce dependency on…
Traffic control pointA location staffed to ensure the continued movement of traffic inside or outside an area of risk during an emergency or disaster.
Trailing EdgeThe part of a wind energy conversion device blade, or airfoil, that is the last to contact the wind.
TrainingRepeated areas of rain, typically associated with thunderstorms, that move over the same region in a relatively short period of time and are capable of…
Training wallA wall built to confine or guide the flow of water.
Tranquil flowDistinguished from rapid flow by a dimensionless number called the Froude number. If the Froude number is less than one, the flow is tranquil.
trans-acting1. A term describing substances that are diffusable and that can affect spatially separated entities within cells. 2. A genetic element (e.g.
trans-acting factorAny of the multiple ancillary DNA -binding proteins that interact with the cis-regulatory DNA sequences to control gene expression.