T

technology

the use of scientific knowledge to solve practical problems (p. 3)

telescope

an optical instrument that uses lenses (or lenses and mirrors) to collect and focus light from distant objects (p. 580)

temperate zones

the regions between latitude 23.5° north and latitude 66.5° north, and between latitude 23.5° south and 66.5° south, which are generally cooler than the tropics (p. 753)

temperature

a measure of how hot or cold an object is compared to a reference point (p. 475)

terminal velocity

the constant velocity of a falling object when the force of air resistance equals the force of gravity (p. 361)

terrestrial planets

the four planets closest to the sun (Mercury, Venus, Earth, and Mars), which are similar in structure to Earth (p. 803)

thermal conductor

a material that conducts thermal energy well (p. 480)

thermal energy

the total potential and kinetic energy related to the motion of all the particles in an object (p. 451)

thermal expansion

the increase in volume of a material when its temperature increases (p. 476)

thermal insulator

a material that conducts thermal energy poorly (p. 480)

thermodynamics

the study of conversions between thermal energy and other forms of energy (p. 482)

thermogram

a color-coded picture using variations in infrared radiation to show variations in temperature (p. 543)

thermometer

an instrument that measures temperature (p. 20)

thermosphere

the outermost layer of Earth's atmosphere (p. 751)

thunder

the sound produced by rapidly expanding air along the path of a lightning discharge (p. 770)

thunderstorm

a small weather system that includes thunder and lightning (p. 770)

tides

the regular rise and fall of water in the oceans (p. 801)

till

glacial sediment left behind when a glacier melts (p. 721)

tornado

a small but intense windstorm that takes the form of a rotating column of air that touches the ground (p. 770)

total internal reflection

the complete reflection of a light ray back into its original medium when the angle of incidence is greater than the critical angle of refraction (p. 578)

transform boundary

a boundary at which tectonic plates slide past each other, moving in opposite directions (p. 682)

transformer

a device that increases or decreases the voltage of two linked AC circuits (p. 644)

transistor

a solid-state component with three layers of semiconductor material, used to turn current on or off or to increase the strength of electronic signals (p. 621)

transition metals

elements that form a bridge between elements on the left and right sides of the periodic table (p. 136)

translucent

a description of a material that scatters light that passes through it (p. 547)

transmutation

the conversion of one element to another through a nuclear reaction (p. 303)

transparent

a description of a material that allows most of the light that strikes it to pass through (p. 546)

transpiration

the loss of water through the leaves of plants (p. 705)

transuranium elements

elements with atomic numbers greater than 92 (p. 304)

transverse wave

a wave that causes a medium to vibrate at right angles to the direction in which the wave travels (p. 501)

trench

a long, deep depression in the ocean floor where old oceanic crust sinks into the mantle (p. 679)

tributary

a smaller stream that flows into a major river (p. 706)

tropic zone

a warm region between latitude 23.5° south and latitude 23.5° north (p. 753)

troposphere

the lowest layer of Earth's atmosphere, where most weather occurs (p. 749)

trough

the lowest point of a transverse wave (p. 501)

tsunami

a large sea wave generated by an underwater earthquake, volcano, or landslide (p. 685)

turbine

a device with fanlike blades that turn when pushed, for example, by water or steam (p. 646)