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tropical air mass a warm air mass from of hydrogen atoms; a molecule that can add /207/es/MHDQ243/tiL12214_disk1of1/0073512214/tiL12214_pagefiles
wave a disturbance or an oscillation that
warm regions more hydrogen atoms because of the pres- moves through a medium
tropical climate zone the climate zone of ence of double or triple bonds wave equation the relationship of the veloc-
the low latitudes; average monthly temper- ity of a wave to the product of the wave-
atures stay above 18°C (64°F), even during V length and frequency of the wave
the coldest month of the year valence the number of covalent bonds an wave front a region of maximum displace-
tropical cyclone a large, violent circular atom can form ment in a wave; a condensation in a sound
storm that is born over the warm, tropical valence electrons electrons of the outer- wave
ocean near the equator; also called hur- most orbital; the electrons that determine wave height the vertical distance of an ocean
ricane (Atlantic and eastern Pacific) and the chemical properties of an atom and wave between the top of the wave crest and
typhoon (in western Pacific) the electrons that participate in chemical the bottom of the next trough
tropical year the time interval between two bonding wavelength the horizontal distance between
consecutive spring equinoxes; used as stan- Van Allen belts belts of radiation caused successive wave crests or other successive
dard for the common calendar year by cosmic-ray particles becoming trapped parts of the wave
tropic of Cancer parallel identifying the and following Earth’s magnetic field lines wave mechanics an alternate name for quan-
northern limit where the Sun appears di- between the poles tum mechanics derived from the wavelike
rectly overhead; located at 23.5°N latitude vapor the gaseous state of a substance that is properties of subatomic particles
tropic of Capricorn parallel identifying the normally in the liquid state wave period the time required for two suc-
southern limit where the Sun appears di- variable a changing quantity usually repre- cessive crests or other successive parts of
rectly overhead; located at 23.5°S latitude sented by a letter or symbol the wave to pass a given point
tropopause the upper boundary of the tro- velocity describes both the speed and di- weak acid an acid only partially ionized
posphere, identified by the altitude where rection of a moving object; a change in because of an equilibrium reaction with
the temperature stops decreasing and re- velocity is a change in speed, in direction water
mains constant with increasing altitude of travel, or both weak base a base only partially ionized be-
troposphere the layer of the atmosphere ventifacts rocks sculpted by wind abrasion cause of an equilibrium reaction with water
from the surface to where the temperature vernal equinox another name for the weathering slow changes that result in the
stops decreasing with height spring equinox, which occurs on or about breaking up, crumbling, and destruction of
trough the low mound of water that is part March 21 and marks the beginning of the any kind of solid rock
of a wave; also refers to the rarefaction, or spring season white dwarf stars one of two groups of stars
low-pressure part, of a sound wave vibration a back-and-forth motion that re- on the Hertzsprung-Russell diagram that
tsunami a very large, fast, and destructive peats itself have a different set of properties than the
ocean wave created by an undersea earth- virtual image an image where light rays ap- main sequence stars; faint, white-hot stars
quake, landslide, or volcanic explosion; a pear to originate from a mirror or lens; this that are very small and dense
seismic sea wave image cannot be projected on a screen wind a horizontal movement of air that
turbidity current a muddy current pro- volcanism volcanic activity; the movement moves along or parallel to the ground,
duced by underwater landslides of magma sometimes in currents or streams
typhoon the name for hurricanes in the volcano a hill or mountain formed by the wind abrasion the natural sand-blasting
western Pacific extrusion of lava or rock fragments from a process that occurs when wind particles
mass of magma below break off small particles of rock and polish
U volt a unit of potential difference equivalent the rock they strike
ultrasonic sound waves too high in frequency to J/C windchill factor the cooling equivalent tem-
to be heard by the human ear; frequencies voltage drop the electric potential difference perature that results from the wind making
above 20,000 Hz across a resistor or other part of a circuit the air temperature seem much lower; the
umbra the inner core of a complete shadow that consumes power cooling power of wind
unconformity a time break in the rock record voltage source a source of electric power in winter solstice in the Northern Hemisphere,
undertow a current beneath the surface of an electric circuit that maintains a constant the time when the Sun reaches its mini-
the water produced by the return of water voltage supply to the circuit mum altitude, which occurs on or about
from the shore to the sea volume how much space something occupies December 22 and identifies the beginning
unit in measurement, a well-defined and vulcanism volcanic activity; the movement of the winter season
agreed-upon referent of magma work the magnitude of applied force times
the distance through which the force acts;
universal law of gravitation every object
in the universe is attracted to every other W can be thought of as the process by which
one form of energy is transformed to an-
object with a force directly proportional to warm front the front that forms when a
other
the product of their masses and inversely warm air mass advances against a cool air
proportional to the square of the distance mass
between the centers of the two masses watershed the region or land area drained Z
unpolarized light light consisting of trans- by a stream; a stream drainage basin zone of saturation the zone of sediments
verse waves vibrating in all conceivable water table the boundary below which the beneath Earth’s surface in which water has
random directions ground is saturated with water collected in all available spaces
unsaturated molecule an organic molecule watt the metric unit for power; equivalent
that does not contain the maximum number to J/s

Glossary G-16