Definitions - t

Tail Boom

A strut that holds the tail (Vane) to the wind generator frame.

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Thermal Break

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Thermal Comfort

The appropriate combination of temperatures, warm or cool, combined with air flow and humidity, which allows one to be comfortable within the confines of a building. This comfort is not usually achieved by the fixed setting of thermostats but through careful design and planning.

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Thermal Conduction

Thermal conduction is the transfer of heat (internal energy) by microscopic collisions of particles and movement of electrons within a body. In the building context this action is most often encountered when assessing how well a building can maintain its internal temperature in relation to the external temperature.

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Thermal Diffusivity

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Thermal Lag

Thermal lag describes a material's thermal mass in terms of time. A material with high thermal mass (high heat capacity and low conductivity) will have a high thermal lag. In effect the addition of (or removal of) energy from one side of the mass 'lags' with respect to the other side.

Thermal lag can be a useful feature, as for instance an outer brick wall on the Sunny Sunset side of a house in Winter would radiate its heat into the property in the evening, aiding with heating.

Thermal lag effects are often incorporated into good passive solar design for buildings.

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Thermal Mass

A thermal mass is a material that absorbs heat from a heat source, and then releases it slowly. This can be used to help regulate the heat in a space by increasing the amount of energy required to change its temperature. Concrete and bricks are often employed as thermal masses in a structure.

This is often used as part of a passive solar designed building.

Note: In order for a thermal mass to work it needs to interact with the air in the space, so cannot be covered.

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Thermal Performance

Thermal Performance refers to how well a structure responds to changes in external temperature during the daily and seasonal cycles. Typically this is in relation to the thermal conductivity of materials or the assemblies of materials.

You want a property to maintain a steady comfortable temperature inside whilst incurring as little energy costs as possible; this is often best achieved by first improving the thermal performance of the property by providing high levels of insulation (high R-Value, low U-Value) on all surfaces and adopting passive solar techniques.

The thermal behavior of a structure is also affected by conditions such as:
  • seasonal and temperature changes,
  • daily diurnals (the difference between highest & lowest temperatures in a day),
  • the amount of solar gain and structural shading,
  • incoming and outgoing heat radiation,
  • water and moisture absorption,
  • air movement,
  • infiltration,
  • pressure differences, etc

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Thermal Pollution
Thermal pollution is the degradation of the water quality by any process that changes the ambient water temperature. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. When water used as a coolant is returned to the natural environment at a higher temperature, the change in temperature can impact organisms by:
  •  decreasing the oxygen supply, and,
  •  affecting the ecosystem composition.

Also by increasing the temperature of water that is normally cold it can increase the likelihood of water born diseases.

Urban runoff, such as storm water discharged to surface waters from roads and parking lots, can also be a source of elevated water temperatures.

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Thermal Resource

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Thermal Storage

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Thermohaline Circulation

Large-scale density-driven circulation in the ocean, caused by differences in temperature and salinity. In the North Atlantic the thermohaline circulation consists of warm surface water flowing northward and cold deep water flowing southward, resulting in a net poleward transport of heat. The surface water sinks in highly restricted sinking regions located in high latitudes.

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Thermosiphon (alt. thermosyphon) refers to a method of passive heat exchange based on natural convection which circulates liquid without the necessity of a mechanical pump. This circulation can either be open-loop, as when liquid in a holding tank is passed in one direction via a heated transfer tube mounted at the bottom of the tank to a distribution point - even one mounted above the originating tank - or it can be a vertical closed-loop circuit with return to the original vessel. Its intended purpose is to simplify the pumping of liquid and/or heat transfer, by avoiding the cost and complexity of a conventional liquid pump.

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Tip Speed Ratio

The ratio of how much faster than the wind speed that the blade tips are moving. Abbreviation TSR.

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Topping Cycle

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Trade Winds

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Treated Wastewater

Wastewater that has been subjected to one or more physical, chemical, and biological processes to reduce its potential of being health hazard.

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Tree Free

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Trickle Irrigation

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Triple Bottom Line

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Trisodium Nitrilotriacetate

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Trombe Wall

A Trombe wall is a very thick, south-facing wall, which is painted black and made of a material that absorbs a lot of heat (such as brick or concrete). A pane of glass or plastic glazing, installed a few inches in front of the wall, helps hold in the heat. The wall heats up slowly during the day. Then as it cools gradually during the night, it gives off its heat inside the building.

A Trombe wall is typically used in passive solar design to help improve energy efficiency of the building.

This article goes into more detail on how to use a Trombe wall and heat your home for free.

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Tropic Levels

A functional classification of species that is based on feeding relationships. The number of steps an organism is from the start of the food chain is a measure of its trophic level. Food chains start at trophic level 1 with primary producers such as plants, move to herbivores at level 2, predators at level 3 and usually finish with carnivores or apex predators at level 4 or 5.

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Tropical Storm Formation

Tropical storms generally form in the eastern portion of tropical oceans and track westward. Hurricanes and typhoons all start out as weak low pressure areas that form over warm tropical waters (e.g., surface water temperature of at least 80 oF). Initially winds and cloud formations over the warm tropical waters are minimal. Both intensify with time. Formation of tropical storms also requires a significant Coriolis effect to induce proper spin in the wind formation. As the storm begins to organize itself into a coherent pattern, it will experience increased activity and intensity.

When a storm develops a clearly recognizable pattern, it is referred to as a tropical depression. When wind speeds reach 35 knots (40.3 mph), it is called a tropical storm and is given a name. When wind speed equals or exceeds 74 mph, the storm is called a hurricane. In the western Pacific, a hurricane is referred to as a typhoon. In waters around Australia it is called a cyclone or willy-willy.

Hurricanes intensify when moving over areas of increased water temperatures, and weaken over colder water surfaces. Upper atmosphere wind shear (different wind direction and speeds at different elevations) will frequently prevent or slow intensification of tropical storms by "spreading out" the storm horizontally and preventing the formation of strong updrafts of warm, humid air. Movement over a land-mass will weaken hurricane winds but will result in large-scale rain that can result in serious flooding. When encountering a strong frontal system (such as a polar front) the hurricane will curve and track along the leading edge of the front or become implanted in it.

Satellite infrared imagery can identify surface water temperatures that will cause tropical storm development.

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Two-Axis Tracking

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