Vocab Flashcards
standard unit
a fixed and reproducible reference value used for the purpose of taking accurate measurements
system of units
a group of standard units and their combinations. The two major systems of units used today are the metric system and the British system
metric system
the decimal system of units most used in the world; also called the mks system
British system
the system of units still often employed in the U.S. and is sometimes referred to as the fps system (foot-pound-second)
length
the measurement of space in any direction
meter
the standard unit of length in the mks system. Equal to 39.37 inches or 3.28 feet.
kilogram
the unit of mass in the mks system; 1 kg has an equivalent weight of 2.2 pounds
time
the continuous forward-flowing of events
second
the standard unit of time. It is now defined in the terms of the frequency of a certain transition in the cesium atom
SI (International System of Units)
a modernized version of the metric system that contains seven base units
derived units
combinations of fundamental units
conversion factor
an equivalence statement expressed as a ratio
significant figures
the method of estimating or expressing error in mathematical operations and measurements
physics
the most fundamental physical science, concerned with the basic principles and concepts that describe the workings of the unviverse
position
the location of an object with respect to another object
motion
the changing of position
scalar
a quantity that has magnitude but no direction
vector
a quantity that has both magnitude and direction
average speed (v)
the distance traveled divided by the change in time
distance (d)
the actual path length between two points
instantaneous speed
how fast an object is traveling at a particular moment or instant
average velocity
the change in position/displacement divided by the change in time
displacement
the directional straight-line between two points
instantaneous velocity
the velocity at a particular instant of time
acceleration
the change in velocity divided by the change in time
average acceleration (a)
the change in velocity divided by the time for the change to occur
acceleration due to gravity (g)
9.80 m/s^2 or 32 ft/s^2
free-fall
the state of motion solely under the influence of gravity
terminal velocity
the maximum velocity reached by a falling object because of air resistance
centripetal acceleration
the “center-seeking” acceleration necessary for circular motion; a=v^2/r
projectile motion
the motion of a projected or thrown object under the influence of gravity
force
any quantity capable of producing motion
unbalance, or net force
the sum of vector forces with a nonzero result. A force capable of producing motion
Newton’s first law of motion
an object will move at a constant velocity unless acted upon by an external unbalanced force
intertia
the natural tendency of an object to remain in a state of rest or in a uniform motion in a straight line
mass
the quantity of matter and a measurement of the amount of inertia that an object possesses
Newton’s second law of motion
the acceleration of an object is equal to the net force on the object divided by the mass of the object; a=F/m
newton
the unit of force in the mks system; 1 kg x m/s^2
weight
a measure of the force due to gravitational attraction (w=mg on the Earth’s surface)
friction
the ever-present resistance to relative motion that occurs whenever two materials are in constant with each other (solids, liquids, or gases)
Newton’s third law of motion
whenever one object exerts a force upon a second object, the second object exerts an equal and opposite force upon the first object
Newton’s law of universal gravitation
the gravitational force between two masses (m1 and m2) is directly proportional to the product of the masses and inversely proportional to the square of the distance r between their centers of mass; F=Gm1m2/r^2
G
the universal gravitational constant; G= 6.67 x 10^ -11 Nm^2/kg^2
buoyant force
the upward force resulting from an object being wholly or partially submerged in a fluid
Archimedes’ principle
an object immersed wholly or partially in a fluid experienced a buoyant force equal in magnitude to the weight of the volume of fluid that it displaced
linear momentum
the product of an object’s mass and its velocity
law of conservation of linear momentum
the total linear momentum of a system remains constant if there is no external unbalanced forces acting on the system
angular momentum
mvr for a mass m going at a speed v in a circle of radius r
torque
the force that tends to produce rotational motion
law of conservation of angular momentum
the angular momentum of a system remains constant unless acted upon by a net torque
work
the product of a force and the parallel distance through which it acts
joule (J)
a unit of energy equivalent to 1 N m or 1 kg m^2/s^2
foot-pound
the unit of work (and energy) in the British system
energy
the capacity to do work
kinetic energy
the energy of motion equal to 1/2 mv^2
potential energy
the energy a body possesses because of its position
gravitational potential energy
the potential energy resulting from an object’s position in a gravitational field; in other words, the stored energy that comes from doing work against gravity
conservation of total energy
the total energy of an isolated system remains constant
conservation of mechanical energy
in an ideal system, the sum of the kinetic and potential energies is constant; Ek + Ep = E (a constant)
power
work or energy per unit time
watt (W)
a unit of power equivalent to 1 kg m^2/s^3 or 1 J/s
horsepower (hp)
a unit of power equal to 550 ft lb/s (746 W)
kilowatt-hour (kWh)
a unit of energy (power x time); P = E/t and E = Pt
alternate energy sources
energy sources that are not based on the burning of fossil fuels and nuclear processes
renewable energy sources
energy sources that cannot be exhausted, such as wind and hydro power
waves
the propagation (spreading) of energy from a disturbance
longitudinal wave
a wave in which the particle motion and the wave velocity are parallel to each other
transverse wave
a wave in which the vibrations are perpendicular to the wave velocity
wavelength
the distance from any point on a wave to an identical point on the adjacent wave
amplitude
the maximum displacement of a wave from its equilibrium position
frequency
the number of oscillations of a wave during one second
hertz (Hz)
one cycle per second. The SI unit of frequency
period (T) (physics)
the time for a complete cycle of motion
electromagnetic waves
a transverse wave consisting of oscillating electric and magnetic fields
speed of light
c= 3.00 x 10^8 m/s
sound
a wave phenomenon caused by variations in pressure in a medium such as air; speed of sound= 340 m/s
intensity (I) of sound wave
the rate of energy transfer through a given area, with units of watts per square meter (W/m^2)
sound spectrum
an ordered arrangement of various frequencies or wavelengths of sound. The three main regions of the sound spectrum are the infrasonic, the audible, and the ultrasonic
decibel (dB)
a unit of sound intensity level; 0.1 bel
ultrasound
sound with frequency above 20 kHz
speed of sound
how fast sound travels in a medium; for example, speed of sound = 344 m/s in air at room temperature
Doppler effect
an apparent change in frequency resulting from the relative motion of the source and the observer
redshift
a Doppler effect caused when a light source, such as a galaxy, moves away from the observer and shifts the light frequency lower, or toward the red end of electromagnetic spectrum
standing waves
a stationary wave from arising from the interference of waves traveling in opposite directions
resonance
a wave effect that occurs when an object has a natural frequency that corresponds to an external frequency
reflection
the change in the direction of a wave when it strikes and rebounds from a surface or the boundary between two media
ray
a straight line that represents the path of light
law of reflection
the angle incidence equals the angle of reflection, as measured relative to the normal, a line perpendicular to the reflecting surface
specular reflection
the reflection from very smooth (mirror) surfaces
refraction
the bending of light waves caused by a seed change as light goes from one medium to another
index of refraction
the ration of the speed of light in a vacuum to the speed of light in a medium
total internal reflection
a phenomenon in which light is totally reflected in a medium because refraction is impossible
dispersion
different frequencies of light refracted at slightly different angles, giving rise to a spectrum
focal length
the distance from the vertex of a mirror or lens to the focal point
concave or converging mirror
a mirror shaped like the inside (concave side) of a small section of a sphere
convex or diverging mirror
a mirror shaped like the outside (convex side) of a spherical section
diffuse reflection
rays reflected from relatively rough surfaces that are not parallel
real image
an image from a mirror or lens that can be brought to focus on a screen
virtual image
an image from a lens or mirror that cannot be brought to focus on a screen
convex or converging lens
a lens that has a surface shape of the out of the outside (convex side) of a spherical section
concave or diverging lens
a lens that has the shape of the outside (concave side) of a spherical section
polarization
the preferential orientation of the electric vector of a light wave to one plane
linearly polarized light
the condition of transverse light waves that vibrate in only one plane
diffraction
the bending of waves when moving past an opening or obstacle that has a size smaller than or equal to the wavelength
principle of superposition (wave)
the combined waveform of two or more interfering waves is given by the sum of the displacements of the individual waves
constructive interference
a superposition of waves for which the combined waveform has a greater amplitude
destructive interference
a superposition of waves for which the combined waveform has a smaller amplitude
quantum
a discrete amount
photoelectric effect
an emission of electrons that occurs when certain metals are exposed to light
photon
a “particle” of electromagnetic energy
dual nature of light
light sometimes behaves as waves and sometimes as particles
line emission spetrum
a set of bright spectral lines of certain frequencies or wavelengths formed by dispersion of light from a gas discharge tube. Each element gives a different set of lines
line absorption spectrum
a set of dark spectral lines of certain frequencies or wavelengths, formed by dispersion of light that has come from an incandescent source source and has then passed through a sample of cool gas
principal quantum number
the numbers n = 1, 2, 3, … used to designate the various principal energy levels that an electron may occupy in an atom
ground state
the lowest energy level of an atom
excited states
the energy levels above the ground state in an atom
fluorescence
the property of a substance, such as the mineral fluorite, of producing visible light while it is being acted upon by ultraviolet light
phosphorescence
a glow of light that persists after the removal of the source of photons needed for excitation of the material’s electrons
x-rays
high-frequency, high-energy electromagnetic radiation formed when high-speed electrons strike a metallic target
laser
acronym for Light Amplification by Stimulated Emission of Radiation; it is coherent, monochramatic light
stimulated emission
process in which an excited atom is caused to emit a photon
universe
everything that is: all energy, matter, and space
celestial sphere
the apparent sphere of the sky on which all the stars seem to appear
ecliptic
the apparent annual path of the sun on the celestial sphere
celestial prime meridian
an imaginary half-circle running from the north celestial pole to the south celestial pole and crossing perpendicular to the celestial equator at the point of the vernal equinox
right ascension
a coordination for measuring the east-west positions of celestial objects. The angle is measured eastward from the vernal equinox in hours, minutes, and seconds
declination
the angular measure in degrees north or south of the celestial equator
parsec (pc)
the distance to a star when the star exhibits a parallax of one second of arc. This distance is equal to 3.26 light years.
photosphere
the sun’s outer surface, visible to the eye
proton-proton chain
a series of stellar nuclear reactions in which four hydrogen nuclei (protons) combine to form one helium nucleus and release energy
apparent magnitude
the brightness of a star (or other celestial object) observed from earth
absolute magnitude
the brightness of a star it would have if it were placed 10 pc (32.6 ly) from earth
H-R diagram
the plot of the absolute magnitude versus the temperature of stars
main sequence
the narrow band on the H-R diagram on which most stars fall
red giants
a relatively cool, very bright star that has a diameter much larger than average
white dwarfs
a hot white star that has a much smaller diameter and much higher density than average. It is believed to be the final stage of a low-mass star
nebulae
vast clouds of interstellar gas and dust
nucleosynthesis
the creation of nuclei of elements inside stars
planetary nebula
a luminous shell of gas ejected from a old, low-mass star
brown dwarfs
low-mass objects that are larger than a typical planet but do not have enough mass to begin fusion in their cores. Also called “failed stars”
nova
a white dwarf star that suddenly increases dramatically in brightness for a brief period of time
supernova
an exploding star
neutron star
an extremely high-density star composed almost entirely of neutrons
black hole
an object whose gravity is so strong that the escape velocity is equal to or greater than the speed of light; thus no radiation can escape from the object
galaxy
a large-scale aggregate of stars (plus some gas and dust) held together by gravity. Galaxies have a spiral, elliptical, or irregular structure. Each contains, on average, 100 billion solar masses
globular clusters
a large, spherical group of gravitationally bound stars, usually found in the outlying regions of the galaxy
Local Group
the cluster of galaxies that includes our own Milky Way
dark matter
the as-yet-unidentified nonluminous matter in the universe
cosmology
the study of the structure and evolution of the universe
Hubble’s law
the recessional speed of a distant galaxy is directly proportional to its distance away
Big Bang
theory of the beginning of the universe that states that the known universe was smaller hotter, and denser in the past, and that is began rapidly expanding 13.7 billion years ago
cosmic microwave background
the microwave radiation that fills all space and is believed to be the redshifted glow from the Big Bang
astronomy
the scientific study of the universe, which is the totality of all matter, energy, space, and time
solar system
the sun, nine planets and their satellites, the asteroids, the comets, meteoroids, and interplanetary dust
geocentric model
the old false theory of the solar system, which placed the Earth at its center
heliocentric model
the model of the solar system that places the sun at its center
law of elliptical orbits
all planets move in elliptical orbits around the sun, with the sun at one focus of the ellipse
astronomical unit (AU)
the average distance between the earth and the sun, which is 93 million miles
law of equal areas
an imaginary line (radial vector) joining a planet to the sun sweeps out equal areas in equal periods of time
harmonic law (Kepler’s third law)
the square of the sidereal period of a planet is proportional to the cube of its semimajor axis (one-half the major axis
terrestrial planets
the four inner planets: Mercury, Venus, Earth, and Mars. All are similar to the Earth in general chemical and physical properties
Jovian planets
the four outer planets: Jupiter, Saturn, Uranus, and Neptune. All have characteristics resembling those of Jupiter
prograde motion
orbital or rotational motion in the forward direction. In the solar system, this is west-to-east, or counterclockwise, as viewed from above the Earth’s North Pole
retrograde rotation
orbital or rotational motion in the backward direction. In the solar system, this is east to west, or clockwise, as viewed from above the Earth’s North Pole
sidereal period
the orbital or rotational period of any object with respect to the stars
conjunction
when two planets are lined up with respect to the sun
opposition
the time at which a planet is on the opposite side of the Earth from the sun
albedo
the fraction of incident sunlight reflected by a body’s surface
rotation
the turning of an object about an axis passing through the mass
revolution
the movement of one mass around another
Foucault pendulum
a pendulum that is used to demonstrate the rotation of the Earth
parallax
the apparent motion, or shift, that occurs between two fixed objects when the observer changes position
aberration of starlight
the apparent displacement in the direction of light coming from a star that results from the orbital motion of the Earth
dwarf planets
a new class of planets, of which there are three: Pluto, Ceres, and Eris
solar nebula
a large, swirling volume of interstellar cold gas and dust that contracted under the influence of its own gravity and formed in the shape of flattened rotating disk
condensation theory
a process of solar system formation in which interstellar dust grains act as condensation nuclei
summer solstice
the farthest point of the sun’s latitude north of the equator (for the Northern Hemisphere), around June 21. The beginning of summer
winter solstice
the farthest point of the sun’s latitude south of the equator (for the Northern Hemisphere), around December 22. The beginning of winter
autumnal equinox
the point where the sun crosses the celestial equator from north to south, around September 22. The beginning of fall
vernal equinox
the point where the sun crosses the celestial equator from south to north, around March 21. The beginning of spring
tropical year
the time interval from one vernal equinox to the next
sidereal year
the time interval for the Earth to make one complete revolution around the sun with respect to any particular star other than the sun
precession
the slow rotation of the axis of spin of the Earth around an axis perpendicular to the ecliptic plane. The rotation is clockwise as observed from the north celestial pole
atoms
the smallest particle of an element that can enter into a chemical combination
electrons
negatively charged subatomic particles
quantum mechanics
the branch of physics that replaced the classical-mechanical view (that everything moved according to exact laws of nature) with the concept of probability. Schrodinger’s equation forms the basis of quantum wave mechanics
nucleus
the central core of an atom; composed of protons and neutrons
protons
positively charged particles in the nuclei of atoms
neutrons
neutral particles found in the nuclei of atoms
nucleons
a collective term for neutrons and protons (particles in the nucleus)
atomic number (Z)
it is equal to the number of protons in the nucleus of an atom
element
a substance in which all the atoms have the same number of protons (same atomic number)
neutron number (N)
the number of neutrons in the nucleus of an atom
mass number (A)
the number of protons plus the number of neutrons in a nucleus; the total number of nucleons
isotopes
form of atoms of an element that have the same numbers of protons, but differ in their numbers of neutrons
atomic mass
the average mass of an atom in naturally occurring samples
strong nuclear force
the short-range force of attraction that acts between two nucleons and holds the nucleus together
radioactive isotopes
an isotope that undergoes spontaneous decay
radioactivity
the spontaneous process of a sample of radionuclide undergoing a change by the mission of particles or rays
alpha decay
the disintegration of a nucleus into a nucleus of another element, with the emission of an alpha particle
beta decay
the disintegration of a nucleus into a nucleus of another element, with the mission of a beta particle
gamma decay
an event in which a nucleus emits a gamma ray and becomes a less energetic form of the same nucleus
half-life
the time it takes for half the nuclei in a sample of a given radionuclide to decay
carbon-14 dating
a procedure used to establish the age of ancient organic remains by measuring the concentration of carbon-14 and comparing it to that of present-day organic remains
chain reaction
occurs when each fission event causes at least one more fission event
critical mass
the minimum amount of fissionable material necessary to sustain a chain reaction
fusion
a process in which smaller nuclei are fused to form larger ones, with the release of energy
plasma
a high-temperature gas of electrons and protons or other nuclei
mass defect
any decrease in mass during a nuclear reaction
temperature
a measure of the average kinetic energy of the molecules in a sample
Fahrenheit scale
a temperature scale with 32°F as the ice point and 212°F as the steam point
Celsius scale
a temperature with 0°C as the ice point and 100°C as the steam point
Kelvin scale
the “absolute” temperature scale that takes absolute zero as 0 K
calories (cal)
the amount of heat necessary to raise one gram of water one degree Celsius at normal atmospheric pressure
heat
a form of energy; energy in transit from one body to another as a result of a temperature difference
kilocalories (kcal)
the amount of heat necessary to raise one kilogram of water one degree Celsius at normal atmospheric pressure
British thermal unit (Btu)
the amount of heat required to raise one pound of water one degree Fahrenheit at normal atmospheric pressure
specific heat
the amount of heat energy in kilocalories necessary to raise the temperature of one kilogram of the substance one degree Celsius
latent heat
the heat associated with a phase change
conduction
the transfer of heat energy by molecular collisions
convection
the transfer of heat through mass movement
radiation
the transfer of energy by means of electromagnetic waves
phases of matter
the physical forms of matter; most commonly solid, liquid, and gas
kinetic theory
a gas consists of molecules moving independently in all directions at high speeds (the higher the temperature, the higher the average speed). colliding with each other and the walls of the container, and having a distance between molecules that is large, on average, compared with the size of the molecules themselves
pressure
the force per unit area; p = F/A
ideal gas law
relates the pressure, volume, and absolute temperature of a gas; p1V1T1=p2V2T2
thermodynamics
the science of dealing with the production of heat, the flow of heat, and the conversion of heat to work
first law of thermodynamics
the heat energy added to a system must go into increasing the internal energy of the system, or any work done by the system, or both. The law, which is based on the conservation of energy, also states that heat energy removed from a system must produce a decrease in the internal energy of the system, or any work done on the system, or both
heat engine
a device that uses heat energy to preform useful work
second law of thermodynamics
it is impossible for heat to flow spontaneously from an object having a lower temperature to an object having a higher temperature
third law of thermodynamics
a temperature of absolute zero can never be attained
heat pump
a devise used to transfer heat from a low-temperature reservoir to a high-temperature reservoir
entropy
a measure of the disorder of a system
chemistry
the division of physical science that studies the composition and structure of matter and the reactions by which substances are changed into other substances
element
a substance in which all the atoms have the same number of protons (atomic number)
compound
a substance composed of two or more elements chemically combined in a definite fixed proportion by mass
mixture
a type of matter composed of varying proportions of two or more substances that are just physically mixed, not chemically combined
solution
a mixture that is uniform throughout. Also called a homogeneous mixture
unsaturated solution
a solution in which more solute can be dissolved at the same temperature
saturated solution
a solution that has the maximum amount of solute dissolved in the solvent at a given temperature
supersaturated solution
a solution that contains more than the normal maximum amount of dissolved solute at a given temperature and hence is unstable
molecule
an electrically neutral particle composed of two or more atoms chemically combined
allotropes
two or more forms of the same element that have different bonding structures in the same physical phase
periodic law
the properties of elements are periodic functions of heir atomic numbers
representative elements
the A group of elements in the periodic table
transition elements
the B group of elements in the periodic table
inner transition elements
the lanthanides and actinides, the two rows at the bottom of the periodic table, make up the inner transition elements
periods (chemistry)
one of the seven horizontal rows of the periodic table
groups
the vertical columns in the periodic table
metal
an element whose atoms tend to lose valence electrons during chemical reactions
nonmetal
an element whose atoms tend to gain (or share) valence electrons during chemical reactions
electron configuration
the order of electrons in the energy levels of an atom
valence shell
an atom’s outer shell, which contians the valence electrons
valence electrons
the electrons that are involved in bond formation, usually those in an atom’s outer shell
ionization energy
the amount of energy it takes to remove an electron from an atom
ion
an atom, or chemical combination of atoms, that has a net electric charge
noble gases
the elements of Group 8A of the periodic table (He, Ne, Ar, Kr, Xe, Rn)
alkali metals
the elements in Group 1A of the periodic table, except for hydrogen (Li, Na, K, Rb, Cs, Fr)
halogens
the elements in Group 7A of the periodic table (F, Cl. Br, I, At)
alkaline earth metals
the elements in Group 2A of the periodic table (Be, Mg, Ca, Sr, Ba, Ra)
limiting reactant
a starting material that is used up completely in a chemical reaction
formula mass
the sum of the atomic masses of the atoms showing in the chemical formula of he compound or element
law of definite proportions
different samples of a pure compound always contain in the same elements in the same proportion by mass
excess reactant
a starting material that is only partially used up in a chemical reaction
mole (mol)
the quantity of a substance that contains 6.02 X 10^23 formula units (the number of atoms in exactly 12 g of carbon-12)
Avagadro’s number
6.02 X 10^23, sybolized N a ; the number of entities in a mole
limiting reactant
a starting material that is used up completely in a chemical reaction
octet rule
in forming compounds, atoms tend to gain, lose, or share electrons to achieve electron configurations of the noble gases
ionic compounds
compounds formed by an electron transfer process in which one or more atoms lose electrons and one or more atoms gain them to form bonds
Lewis symbol
the element’s symbol represents the nucleus and inner electrons of an atom, and the valence electrons are shown as dots arranged around the symbol
Lewis structures
“electron dot” symbols used to show valence electrons in molecules and ions of compounds
cations
positive ions; so called because they move forward the cathode (the negative electrode) of an electrochemical cell
anions
negative ions; so called because they move toward the anode (the positive electrode) of an electrochemical cell
ionic bonds
electrical forces that hold the ions together in the crystal lattice of an ionic compound
covalent bond
the force of attraction caused by a pair of electrons being shared by two atoms
polar covalent bond
one in which the pair of bonding electrons is unequally shared, leading to the bond’s having a slightly positive end and a slightly negative end
electronegativity
a measure of the ability of an atom to attract shared electrons to itself
polar molecule
a molecule that has a positive end and a negative end; that is, one has a dipole
chemical properities
characteristics that describe the chemical reactivity of a substance; that is, its ability into another substance
chemical reaction
a change that alters the chemical composition of a substance
reactants
the original substances in a chemical reaction
products
the substances formed during a chemical reaction
combination reaction
one in which at least two reactants combine to form just one product A + B → AB
decomposition reaction
one in which only one reactant is present and breaks into two (or more) products:
AB → A + B
acid
a substance that gives hydrogen ions (or hydronium ions) in water
equilibrium
a dynamic process in which the reactants are combining to form the products at the same rate at which the products are combining to form the reactants
base
a substance that produces hydroxide ions in water
pH
a measure (on a logarithmic scale) of the hydrogen ion (or hydronium ion) concentration in a solution
acid-base reaction
the H+ of acid unites with the OH- of the base to form water, while the cation of the base combines with the anion of the acid to form a salt
salt
an ionic compound that contains any cation except H+ combined with any anion except OH-
acid-carbonate reaction
an acid and a carbonate (or hydrogen carbonate) react to give carbon dioxide, water, and a salt
double-replacement reactions
reactions that take form AB + CD → AD + CB
precipitate
an insoluble solid that appears when two clear liquids (usually aqueous solutions) are mixed
mineral
any naturally occurring inorganic crystalline substance (element or compound) that possesses a fairly definite chemical composition and a distinctive set of physical properties
silicates
any one of numerous minerals that have the oxygen and silicon tetrahedron as their basic structure
Mohs scale
a list of 10 minerals used to measure the hardness of other minerals
cleavage
the splitting of a mineral along an internal molecular plane
streak
the color of a powdered mineral on a streak plate (unglazed porcelain)
luster
the appearance of a mineral’s surface in reflected light
rock
a solid, cohesive natural aggregate of one or more minerals
igneous rocks
rock formed by the cooling and solidification of hot, molten material
sedimentary rocks
rock formed from lithification, or consolidation, of layers of sediment
metamorphic rocks
rock that results from a change in preexisting rock due to high pressure or temperature or both
uniformitarianism
the principle that the same processes operate on and within the Earth today as in the past. Hence the present is considered the key to the past
rock cycle
the cyclic changes of rock, during which the rock is created, destroyed, and metamorphosed by the Earth’s internal and external geologic processes
magma
hot, molten, underground rock material
lava
magma that reaches the Earth’s surface through a volcanic vent
plutons
intrusive igneous rocks, formed below the surface of the Earth by solidification of magma
pyroclastics
solid material emitted by volcanoes; range in size from fine dust to large boulders
viscosity
the internal property of a substance that offers resistance to flow
sediment
mineral or organic mater deposited by water, air, or ice
lithification
the process of forming sedimentary rock from sediment; also called consolidation
bedding
the stratification of sedimentary rock formations
metamorphism
the process by which the structure and mineral content of a rock are changed while the rock remains solid
contact metamorphism
a change in rock brought about primarily by heat rather than pressure
shear metamorphism
a change in rock brought about primarily by pressure rather than heat
regional metamorphism
a change in rock over a large area, brought about by both heat and pressure
hydrothermal metamorphism
the chemical alteration of preexisting rocks by chemically reactive, hot-water solutions, which dissolve some ions from the original minerals and replace them with other ions, thus changng the mineral composition of the rock
geology
the study of the planet Earth; its dynamics, composition, structure, and history.
seismic waves
the waves generated by the energy release of an earthquake
outer core
part of the innermost region of he Earth, which is composed of two parts: a solid inner core and a molten highly viscous outer core
inner core
the innermost region of the Earth, which is solid and probably composed of about 85% iron and 15% nickel
mantle
the interior region of the Earth between the core and the crust
crust
the thin outer layer of the Earth
Moho (Mohorovicic discontinuity)
the boundary between the Earth’s crust and mantle
lithosphere
the outermost solid portion of the Earth, which includes the crust and part of the upper mantle
asthenosphere
the rocky substratum below the lithosphere that is hot enough to be deformed and is capable of internal flow
continental drift
the theory that continents move, drifting apart or together
Pangaea
the giant supercontinent that is believed to have existed over 200 million years ago
mid-ocean ridge
a series of mountain ranges on the ocean floor, more than 84,000 km in length, extending through the North and South Atlantic, the Indian Ocean and the South Pacific
seafloor spreading
the theory that the seafloor slowly spreads and moves away from mid-ocean ridges. Believed to be due o convection cycles of subterranean molten material that cause the formation of the ridges and a surface motion in a lateral direction from the ridges
remanent magnetism
the magnetism retained in rocks containing ferrite minerals after these rocks solidify in the Earth’s magnetic field
plate tectonics
the theory that the Earth’s lithosphere is made up of rigid plates that are in slow relative motion with respect to each other
divergent boundary
a region where plates of the lithosphere are moving away from one another
convergent boundary
a region where moving plates of the lithosphere are driven together, causing one of the plates to be consumed into the mantle as it descends beneath an overriding plate
transform boundary
a region of the lithosphere where a moving plate slides along one side of another without creating or destroying the lithosphere
isostasy
the concept that the Earth’s crustal material “floats” in gravitational equilibrium on a “fluid” substratum
subduction
the process in which one plate is deflected downward beneath another plate into the asthenosphere
volcano
a hill or mountain formed from lava and rock fragments ejected through a vent in the Earth’s surface
earthquake
the release or transfer of energy because of sudden movement resulting from stresses in the Earth’s lithosphere
faults
a break or fracture in the surface of a planet or moon along which movement has occured
focus
the point within the Earth at which the initial energy release of an earthquake occurs
epicenter
the point on the surface of the Earth directly above the focus of an earthquake
tsunamis
an unusally large sea wave produced by a seaquake or undersea volcanic eruption
fold
a buckling of rock layers into arches (anticlines) and troughs (synclines) as a result of compressional forces
volcanic mountains
mountains that have been bullt by volcanic eruptions
fault-block mountains
mountains that were built by normal faulting, in which giant pieces of the Earth’s crust were uplifted
fold mountain
mountains characterized by folded rock strata, with external evidence of faulting and central evidence of igneous and metamorphic activity. Fold mountains are believed to be formed at convergent plate boundaries
geologic time
the time span that covers the long history of the Earth
fossil
a remnant or trace of an organism preserved from prehistoric times
paleontology
the systematic study of fossils and prehistoric life forms
replacement fossil
fossil formed when a mineral slowly replaces parts of a buried organism
mold
a hollow depression formed when an embedded shell or bone is dissolved out of a rock
cast
fossil formed when new mineral material fills a mold and hardens
trace fossil
fossil imprint made by the movement of an animal
amber
fossilized tree resin
principle of original horiontality
sediments and lava flows are deposited as horizontal layers
principle of superposition (geology)
the principle that in a succession of stratified deposits, the younger layers lie over the older layers
principle of cross-cutting relationships
an igneous rock is younger than the rock layers it has intruded (cut into or across)
unconformity
a break in the geologic rock record
index fossils
a fossil that is related to a specific span of geologic time
correalation
establishing the equivalence of rocks in separate regions; correlation by fossils is an example
eons
the largest unit of geologic times. Eons are divided into eras
eras
an interval of geologic time that is a subdivision of an eon and is made up of periods and epochs
periods (geology)
an interval of geologic time that is a subdivision of an era and is made up of epochs
absolute (numerical) geologic time
the time of past geologic events, established on the basis of the radioactive decay of certain atomic nuclei
radiometric dating
a general name for dating rocks and organic remains by measuring the rate of decay of radionuclides that the rocks and remains contain
geologic time scale
a relative time scale based on the fossil contents of rock strata and the principles of superposition and cross-cutting relationships
Cambrian explosion
the great proliferation of life forms that followed the extinction event at the beginning of the Paleozoic era
Great Dying
the most devastating extinction known to geologists; it marked the beginning of the Mesozoic era
epochs
an interval of geologic time that is a subdivision of a period
atmospheric science
the investigation of every aspect of the atmosphere
meteorology
the study of the lower atmosphere
photosynthesis
the process by which plants convert CO2 and H20 to sugars and oxygen
troposphere
the region of the Earth’s atmosphere from the ground to about 16 km
weather
the atmospheric conditions of the lower troposphere
stratosphere
the region of the Earth’s atmosphere approximately 16 to 50 km in altitude
mesosphere
the region of the Earth’s atmosphere that lies between approximately 50 and 80 km in altitude
thermosphere
the region of the Earth’s atmosphere extending from about 80 km in altitude to the outer reaches of the atmosphere
ozone
O3, a form of oxygen found naturally in the atmosphere in the ozonosphere. It is also a constituent of photochemical smog
ozonosphere
a region of the atmosphere between approximately 15 and 50 km in altitude; characterized by ozone concentration
ionosphere
the region of the atmosphere between about 70 km and several hundred kilometers in altitude. It is characterized by a high concentration of ions
insolation
the solar radiation received by the Earth and its atmosphere; INcoming SOLar radiATION
Rayleigh scattering
the preferential scattering of light by air molecules and particles that accounts for the blueness of the sky. The scattering is proportional to 1/λ^4
greenhouse effect
the heat-retaining process of atmospheric gases, such as water vapor and CO2, that results from the selective absorption of long-wavelength terrestrial radiation
barometer
a device used to measure atmospheric pressure
relative humidity
the ratio of the actual moisture content of a volume of air to its maximum moisture capacity at a given temperature
dew point
the temperature at which a sample of air becomes saturated; that is, has a relative humidity of 100%
psychrometer
an instrument used to measure relative humidity
anemometer
an instrument used to measure wind speed
rain gauge
an open, calibrated container used to measure amounts of precipitation
Doppler radar
radar that uses Doppler effect on water droplets in clouds to measure the wind speed and direction
wind
the horizontal movement of air; air motion along the Earth’s surface
air currents
vertical air movement
convection cycle
the cyclic movement of matter (such as air) as a result of localized heating and convectional heat transfer
isobar
a line on a weather map denoting locations with the same atmospheric pressure
Coriolis force
a pseudoforce arising in an accelerated reference frame on the rotating (accelerating) Earth. Projectiles are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, as observed in the direction of motion
jet streams
rapidly moving “rivers” of air in the upper troposphere
clouds
a buoyant mass of visible droplets of water and ice crystals in the lower troposphere
lapse rate
the rate of temperature decrease with increasing altitude. In the troposphere, the normal lapse rate is -6.5 C°/km
Bergeron process
the process by which precipitation is formed in clouds
coalescence
the combining of small droplets of water vapor to make larger drops
air mass
a mass of air with physical characteristics that distinguish it from other air
source region
the region or surface from which an air mass derives its physical characteristics
front
the boundary between two air masses
lightning
an electric discharge in the atmosphere
thunder
the sound associated with lightning; it arises from the explosive release of electric energy
snowstorm
an appreciable accumulation of snow. When accompanied by high winds and low temperatures, it is referred to as a blizzard
tornado
a violent storm characterized by a funnel-shaped cloud and high winds
tornado watch
the alert issued when conditions are favorable for tornado formation
tornado warning
the alert issued when a tornado has actually been sighted or is indicated on radar
hurricane
a tropical storm with winds of 74 mi/h or greater
storm surge
the great dome of water associated with a hurricane when it makes landfall
hurricane watch
an advisory alert that hurricane conditions are a definite possibility
hurricane warning
an alert that hurricane conditions are expected within 24 hours
pollution
any atypical contributions to the environment resulting from the activities of humans
smog
a contraction of SMoke-fOG, used to describe the combination of these conditions
temperature inversion
a condition characterized by an inverted lapse rate
nitrogen oxides (NOx)
chemical combinations of nitrogen and oxygen, such as No and NO2
photochemical smog
air pollution resulting from the photochemical reactions of hydrocarbons with other pollutants and atmospheric oxygen in the presence of sunlight
sulfur dioxide (SO2)
an atmospheric pollutant formed by the oxidation of sulfur; it contributes to acid rain
acid rain
rain that has a relatively low pH because of air pollution
climate
the long-term average weather conditions of a region of the world
weathering
the physical disintegration and chemical decomposition of rock
permafrost
ground that is permanently frozen
sinkholes
a depression on the land surface where soluble rock (limestone) has been removed by groundwater
erosion
the downslope movement of surface and near-surface materials as a result of gravity and the agents that cause such movements
stream
any flow of water occurring between well-defined banks
flood plain
the land next to a river or stream that can become inundated when the river or stream overflows
meander
the looping, ribbon-like path of a river channel that results from accumulated deposits of eroded material having diverted the stream flow
delta
the accumulation of sediment formed where running water enters a large body of water such s a lake or ocean
glaciers
a large ice mass that consists of recrystallized snow and that flows on a land surface under the influence of gravity
glacial drift
general term for solid material transported and deposited by a glacier
moraines
a ridge of glacial drift
desert
an area on the Earth’s surface that has a severe lack of precipitation
mass wasting
the downslope movement of overburden under the influence of gravity
creep
a type of slow mass wasting that involves the particle-by-particle movement of weathered debris down a slope, which takes place year after year
groundwater
water that soaks into the soil
permeability
a material’s capacity to transmit fluids
water table
the boundary between the zone of aeration and the zone of saturation
aquifer
the body of permeable rock through which groundwater moves
long-shore current
a current along a shore that results from waves that break at an angle to the shoreline
tides
the periodic rise and fall of the water level along the shores of large bodies of water
seamounts
an isolated submarine volcanic structure
continental shelves
the moderately sloping, submerged margin of a continental landmass
continental slopes
the seaward slope beyond the continental shelf. It extends downward to the ocean basin
