abrasion: the process of particles rubbing against each other, wearing down the sharp edges into smaller pieces.
absolute magnitude: how bright a star appears from 32.6 light years away.
absolute zero:temperature at which all molecular motion ceases (0°K, −273.15°C, or −459.67°F).
acid test: tests a mineral or rock for calcite or calcium in its composition.
active continental margin: plate boundary where mountains are formed.
active volcano: volcano that has erupted in recorded history.
advected fog: fog caused by air moving from one region to another region with a different surface temperature.
advection: movement of air from one area to another, creating unusually warm or cold conditions.
air mass: large mass of air at the surface of the Earth with similar characteristics of temperature and humidity throughout the mass.
albedo: reflection of sunlight.
altitude: angle of a celestial object above the horizon.
anemometer: instrument used to determine wind speed.
anticline: parallel rock layers folded upward, like an arch.
aphelion: point in an orbit farthest from the Sun.
apogee: point in an orbit farthest from the Earth.
apparent diameter: the diameter of an object as it appears to an observer; changes with distance.
apparent magnitude: how bright a star appears to someone on Earth.
arid: climates that are extremely dry, with low precipitation and high evapotranspiration.
asteroid belt: the orbiting band of rocks between Mars and Jupiter.
asthenosphere: the outer layer of the Earth's mantle, which has a plastic-like composition; site of convection currents that move the plates on the surface.
astronomical unit: measurement used in the solar system, the average distance from the Earth to the Sun (150,000,000 km or 93,000,000 mi).
atmosphere: the gas layer surrounding the Earth.
atoll: ring of coral reefs surrounding a sunken island.
aurora: light created in the sky by the interference of charged solar particles with the magnetic field of the Earth.
autumnal equinox: September 23, when the vertical ray of the Sun is at the Equator; the entire Earth has 12 hours of day and 12 hours of night.
azimuth: direction along the horizon when looking for an object in the sky.
big-bang hypothesis: says that origin of the universe was when all matter was collected together and exploded, about 15 billion years ago.
blue shift: apparent shortening of starlight as it moves toward you (Doppler).
buoyant: describes a property that causes materials to appear to float in or on a fluid.
caldera: extinct volcano that has a collapsed cone.
capillary: water that works its way upward in the ground through adhesion to rock particles and cohesion to itself.
carbonates: the family of minerals composed of carbon and oxygen.
Cephid: a star that varies in its light output.
chemical weathering: the breaking down of rock material by chemical means, forming a new substance.
chromosphere: reddish layer of the Sun that is hydrogen burning.
cinder cone: steep cone of a volcano formed from ash and loose rock.
cirrus: very high clouds formed by ice crystals; look like feathers; usually associated with fair weather.
clastic: pieces of rocks.
cleavage: the way a mineral splits or breaks along weak bonds in planes.
climate: the overall temperature, precipitation, and weather conditions for an area.
cold front: the leading edge of a cold air mass.
color: an easy test in the identification of minerals, but not always reliable.
column: pillar of rock formed when a stalactite and stalagmite merge.
comet: a mass of frozen gases, ice, and rock that orbits the Sun.
composite volcano: a volcano consisting of a cone of alternating layers of solidified lava and rock particles.
compound: a molecule made up of two or more elements.
condensation: the process of a substance changing states from gas to liquid.
conduction: transfer of energy through solids by direct contact.
constellation: a group of stars that appears to be in a pattern.
contact metamorphism: the process of changing rocks into metamorphic rocks by nearby magma.
continental glacier: a thick sheet of ice covering a mass of land all year round, moving outward from the thickest part; found only in Greenland and Antarctica.
continental rise: area which connects the continental slope to the ocean floor.
continental shelf: ocean bottom along the coasts with a low gradient.
continental slope: ocean bottom that connects the continental shelf to the deep ocean floor.
contour farming: planting crops along contour lines on a hill to help prevent soil erosion.
contour interval: the elevation difference between contour lines.
contour line: line connecting points of equal elevation.
convection: transfer of energy in fluids; can create currents by density differences.
converging plate boundary: region where plates move toward each other.
coordinate system: rectangular grid system for plotting points.
Copernicus, Nicholas: astronomer who developed the heliocentric model.
corona: outermost layer surrounding the Sun.
crater: impact mark left on a planet or moon by a collision with a another object.
craton: core rock base of a continent.
creep: slow movement of rocks and sediments down a hillside.
crust: the thin, outer layer of the solid part of the Earth.
crystal shape: the arrangement of molecules in a mineral.
cumulonimbus: cumulus cloud that builds vertically; usually associated with a cold front and thunderstorms.
cumulus: puffy, cotton-like clouds formed by rising air.
cyclogenesis: the process of forming storm systems.
deficit: time during the water budget when drought conditions occur; there is not enough water to supply the needs of an area.
delta: a triangle-shaped area of deposition located at the mouth of an older river.
density: the amount of matter in a given space.
deposition: the rare process of a substance changing states from gas directly to a solid.
derived unit: unit that is a combination of basic units.
dew point:) temperature at which water vapor condenses into liquid water.
discharge: the amount of water in a river or stream that passes a certain point in a given amount of time.
diverging plate boundary: region where plates move apart.
doldrums: region along the Equator where the weather conditions are fairly consistent.
dormant volcano: volcano that has not erupted during recorded history.
drainage basin: the area around a stream that could drain into the stream.
drainage divide: the outer edge between drainage basins.
drift: small particles carried away from larger rocks by glacial meltwater.
drizzle: liquid precipitation that is less than .02 cm in diameter.
dry adiabatic lapse rate: rate at which dry air cools as it rises upward.
dry-bulb temperature: temperature of the air.
dynamic equilibrium: a system that fluctuates, but overall is in balance.
El Niño, La Niña: long-term weather patterns associated with changing global winds and ocean temperatures in the Pacific Ocean.
electromagnetic spectrum: diagram that breaks down energy by wavelength.
epicenter: location on the Earth's surface directly above the focus of an earthquake.
epicycle: small circle made by a planet's orbit in the geocentric model.
equilibrium: a system that is in balance.
erosion: the transportation of weathered materials.
erratic: a large rock that is deposited by a glacier.
explosive eruption: volcanic activity containing thick lava and more gases under pressure; creates steeper cones.
extrusive: rock that forms on the Earth's surface.
eye: center of circulation in a hurricane, where the conditions are calm.
eye wall: area surrounding the eye of a hurricane, where winds are most intense.
fault: a crack or break in a rock.
fault plane: the surface that rocks move along when plates shift.
fault-block mountains: mountain range formed when sections of sedimentary rocks are tilted upward in sections.
felsic: magma that is aluminum or silica based, lighter in color, and less dense than mafic magma.
fetch: length of open ocean for wind to create waves.
field: an area where there is a measurable amount of a specific value at every point.
flood plain: the area along the banks of a meandering river that are prone to flooding at various times.
focus: exact site of the origin of an earthquake, below the epicenter.
folded mountains: mountain range formed by the collision of continental plates, causing the rock layers to be crumpled.
foliated texture: layered mineral crystals in a metamorphic rock.
fossil: evidence that life was present, preserved in a rock.
fracture: the uneven breaking or cracking of a mineral.
front: the boundary between two air masses.
frost point: dew point temperature, below 0°C.
Fujita scale: scale for measuring the intensity of a tornado from F0 to F5.
Galileo: scientist whose observations supported the Copernican model.
geocentric: a model in which Earth is at the center of the universe.
geyser: groundwater deep in the Earth that turns to steam and is forced to the surface when enough pressure is generated.
granule: one of the individual cells that make up the photosphere of the sun.
graphical model: a graph showing relationships.
greenhouse effect: incoming (shortwave) energy is reradiated as heat energy (longwave) and trapped by the greenhouse gases in the atmosphere; causes global warming.
greenhouse gas: a gas produced from burn fossil fuels, which hold and trap heat energy; carbon dioxide is an example.
ground fog: fog formed by radiational cooling.
guyot: flat-topped seamount, eroded by ocean waves while exposed.
hail: layers of ice formed in a large thunderstorm cloud that fall to Earth.
half-life: the amount of time it takes a radioactive element to decay into half of its original mass.
heliocentric: sun-centered model of the solar system.
Horse Latitudes: area of little surface winds and high pressure along 30° N latitude.
hot spot: weak or thin area in a plate that allows magma to rise up and reach the surface.
hot spring: groundwater heated by magma rising to the surface through an opening in the ground.
hurricane: low-pressure system with sustained winds of 74 mph or greater.
hydrosphere: the water layer of the Earth.
hygrometer: an instrument used to measure humidity; can be made from hair.
igneous: rock formed when molten rock cools.
impermeable: rock that water cannot sink into or through.
index fossil: a fossil of an organism that occurred for a short amount of time and over a widespread area; used to connect rock layers over long distances.
inference: an educated guess based on collected data.
infiltration: water sinking into the ground.
inner core: the solid center of the Earth, composed of iron and nickel.
insolation: a combination of the words incoming solar radiation.
instrument: tool used to extend your senses and gather data.
International Date Line: the longitude line measuring 180° where the day changes.
Intertropical Convergence Zone: area along the Equator where trade winds from the Northern and Southern hemispheres meet, forming thunderstorms.
intrusion: magma that crosses through other rock layers, cooling and hardening before reaching the surface.
intrusive: rock that forms below the Earth's surface (plutonic).
inversion: an atmospheric condition where warm air is on top of cold air.
isobar: line connecting areas of equal pressure on a map.
isoline: line that connects equal values.
isosurface: three-dimensional diagram showing surfaces connecting equal values.
isotherm: line connecting areas of equal temperature on a map.
isotopes: two elements that have the same atomic number but different atomic masses.
jet stream: band of fast-moving air in the upper troposphere.
Jovian planet: outer planet (Jupiter, Saturn, Uranus, and Neptune) consisting of a gaseous surface.
Kepler, Johnannes: astronomer who developed three laws of planetary motion: planets move in elliptical orbits; planets sweep out equal area in equal time; the period of revolution is proportional to the distance to the Sun.
kettle: a steep-sided pond created by a glacier when a block of ice is left behind as the glacier retreats.
key bed: a layer in the rock record showing an event that occurred quickly and over a widespread area; is used like an index fossil.
land breeze: local wind that forms at night along a beach due to uneven cooling rates of land and water, wind moves from land to water.
lateral moraine: the pile of rocks that accumulate along the edges of a glacier.
latitude: coordinate lines for locating a position on Earth that run east and west and are parallel to each other, running from 0° to 90° (angle from the equator).
lava: liquid rock on the surface of the Earth.
leeward: the side opposite from the prevailing wind direction.
lifting condensation level: formula used to find the height at which clouds can form.
light year: the distance that light travels in one year, about 9.5 trillion kilometers.
lightning: electricity generated by a thunderstorm.
line graph: points plotted on a coordinate system and connected with a line.
lithosphere: the rock layer on the outer edge of the Earth.
local noon: occurs when the Sun is at its highest point for the day.
longitude: coordinate lines for locating position on Earth that run north and south through the poles, are farthest apart at the Equator, run from 0° to 180°, are equal in length, and are measured from the Prime Meridian.
longshore current: a current moving parallel to the coast.
low-pressure center: counterclockwise circulation center, formed along a stationary front in the Northern Hemisphere.
luminosity: actual brightness of a star.
lunar eclipse: the Moon goes out of view as it moves into the Earth's shadow; occurs during the Full Moon phase.
luster: the way a mineral shines in reflected light.
L-wave: longitudinal wave created by the P-wave and S-waves of an earthquake at the surface of the Earth; these are the slowest and move outward like ripples on a pond.
mafic: magma that is iron or magnesium-based, darker in color, and more dense than felsic magma.
magma: liquid rock below the Earth's surface.
magnetic declination: the number of degrees that a compass needle is pulled away from True North to point toward Magnetic North.
Magnetic North: the area near Hudson Bay, Canada, where the Earth's magnetic field is strongest in the Northern Hemisphere (location changes over time).
main sequence star: star that falls into broad band along the H-R diagram.
mantle: the layer below the crust; about 2,900 km thick; contains rocks rich in iron, magnesium, and silicon.
maria: large, flat areas on the Moon.
Marianas Trench: deepest trench in the world; lies off the coast of Japan.
mathematical model: an equation representing an idea.
matter: anything that has mass and takes up space.
mechanical model: a physical model with moving parts.
mechanical weathering: the physical breaking down of rock, changing only its size (smaller); examples are ice wedging, plant action, and pressure unloading.
medial moraine: the moraine created when two glaciers meet and their lateral moraines merge.
mental model: an idea or model that exists in your mind.
Mercalli Scale: scale for measuring earthquakes based on obsevations.
meridian: line of longitude.
mesopause: region between the mesosphere and the thermosphere.
mesosphere: part of the atmosphere between the stratosphere and the thermosphere; temperatures decrease with altitude.
metamorphic: existing rock that undergoes extreme heat or pressure and is recrystallized.
meteor: a meteoroid that enters the Earth's atmosphere; also known as a shooting star.
meteorite: a meteor that reaches the surface of the Earth.
meteoroid: a rock fragment orbiting in the solar system.
mid-latitude low: low-pressure system that forms along a stationary front.
mid-ocean ridge: area between two diverging plates, where magma reaches the surface and causes an area of increased elevation and new crust along the ocean floor.
Milankovic period: long term climate changes due the wobble of the Earth's revolution around the Sun.
Milky Way galaxy: the spiral galaxy that includes our solar system near its outer edge.
model: a scale representation of another object or idea.
Moh's hardness scale: a relative scale ranging from 1 to 10, measuring whether a mineral can scratch another mineral.
moist adiabatic lapse rate: rate at which humid air cools as it rises upward.
monsoon: seasonal wind pattern changes that cause rainy and dry seasons.
moraine: large area of deposition left behind from the advance of a glacier.
natural selection: theory by Charles Darwin which states that organisms best fit for their environment will survive and pass along these traits.
neap tide: tide with the smallest tidal range; during both quarter phases.
nebula: a cloud of gas and dust in space.
Newton, Issac: developed the universal law of gravity.
nonrenewable resources: natural resources that cannot be replenished for millions of years, if at all.
normal fault: fault that occurs when rocks are pulled apart, causing one side to move downward.
oblate spheroid: the shape of the Earth; not a perfect sphere, but flatter at the poles and slightly bulging at the Equator.
observation: data that is collected through your senses.
occluded front: front that forms when a cold front catches up to a warm front.
orogeny: a mountain-building period or event.
outer core: the iron- and nickel-rich liquid layer near the center of the Earth.
outgassing: gases that escape to the atmosphere during volcanic eruptions.
outwash plain: sandy area downstream from a moraine created by drift particles and meltwater from a glacier.
overriding plate: crustal plate which collides with a more dense plate and moves above the plate.
overturning: rock layers that are flipped upside-down during the mountain-building process.
parallax:) the apparent change in the position of stars due to Earth's revolution.
parallels: lines that never meet, such as latitude.
passive continental margin: area along the coast where sediments are deposited.
pause: a region separating two layers of the atmosphere.
penumbra: the lighter, gray area of a shadow.
percent error: formula used to find the inaccuracy of a measurement.
perigee: position in an orbit that is closest to the Earth.
perihelion: point in an orbit that is closest to the Sun.
permeability: the rate at which water sinks into the ground.
photosphere: outer layer of the Sun.
physical model: a representation of an object that you can hold.
phytoplankton: microscopic plants floating freely in the ocean.
plutonic: rock that forms below the Earth's surface (intrusive).
Polaris: the North Star, located in the Little Dipper constellation.
pollution: a substance that harms living organisms or the environment.
porosity: the percentage of open space between soil particles and rocks.
porphyritic texture: rocks that have different-sized crystals, created at different times.
prevailing westerlies: planetary winds between 30° and 60° latitude; they guide weather systems for the United States (from SW to NE).
prime meridian: 0° longitude line, running though Greenwich, England.
profile: side view of land on a topographic map.
psychrometer: an instrument with a dry-bulb thermometer and a wet-bulb thermometer; used to measure dewpoint and relative humidity.
Ptolemy: astronomer who developed the geocentric model.
pulsar: a star that sends energy out in pulses.
punctuated equilibrium: theory that organisms just "appear" on Earth.
P-waves: primary waves generated by an earthquake; these compression waves are the fastest and travel through solids, liquids, and gases.
radiation: transfer of energy through a vacuum; the way in which the Sun supplies the Earth with energy.
radioactive element: an atom that emits gamma rays, alpha particles, and beta particles; can be used to determine age.
radiosonde: weather balloon that carries instruments to record data and transmit readings to a base unit.
rain: liquid precipitation larger than .02 cm in diameter.
recharge: the period of time during the water-budget cycle when the water in the ground is being replenished.
red giant: stage of the life cycle of a star in which it expands and cools.
red shift: apparent lengthening of starlight as it moves away from you (Doppler).
regionally metamorphic: rock that undergoes intense heat and pressure over large areas.
relative humidity: a measure of how much water is in the air compared to how much it can hold, given as a percentage.
renewable resources: energy sources or other natural resources that are replenished shortly after being used.
retrograde motion: the apparent backward movement of a celestial object.
reverse fault: rocks that crack and are thrust upward, forming an overhang; caused by the compression of rocks.
Richter Scale: scale for measuring earthquakes based on energy released.
rift eruption: lava flows in long, narrow cracks of the Earth's crust.
rift valley: the space between diverging plates.
rip currents: strong surface currents that move like small rivers perpendicular to the shoreline, caused by water returning from the beach to the ocean.
rock cycle: the continuous flow from one type of rock to another.
Saffir-Simpson scale: scale for measuring hurricane intensity, from Category I to Category V.
salinity: amount of dissolved salts in water.
saturated: cannot hold any more water, as in groundwater or air (humidity).
scalar: field values that measure magnitude.
scale: the proportion of a model in relation to the original.
scientific notation: a method of converting very large or very small numbers into a convenient value using exponents.
sea breeze: local wind that develops during the day along a beach due to uneven heating of land and water; wind moves from water to land.
seamount: underwater mountain.
sedimentary: rock formed from the compaction and cementation of fragments from other rocks.
seismogram: paper record graphing earthquake motions, created by a seismograph.
seismograph: machine that detects earthquakes.
severe thunderstorm: thunderstorm that has winds in excess of 50 mph and can produce large hail.
shadow zone: area of the Earth shielded from earthquake waves by the outer core (where S-waves are absorbed and P-waves are refracted).
shield cone: broad cone of a volcano resulting from smooth lava flows.
silicates: group of minerals with silicon and oxygen as a base.
sliding plate boundary: region where plates move next to each other.
sling psychrometer: a handheld psychrometer than spins around, used to measure dewpoint and relative humidity.
slip face: the back side of a sand dune.
slump: rock material that is moved downhill as a block of land is uplifted.
solar eclipse: event in which the view of the Sun is blocked by the Moon during a New Moon phase, when the Moon's shadow reaches the Earth.
solar noon: the highest point of the Sun on any day.
solar prominence: flame-like arc extending out from the Sun.
specific gravity: the relative density of a mineral, compared to water.
specific humidity:) a measure of how much water is actually in the air.
spectroscope: instrument for separating visible light into colors.
spiral galaxy: galaxy with bands of stars that rotate around the center.
spring tide: extreme tides during Full and New Moon phases.
stalactite: rock icicle forming from the ceiling of a cave.
stalagmite: rock formation rising up from a cave floor.
station model: a diagram on a weather map showing weather data from a specific city at a given time.
stationary front: initial boundary between two air masses.
storm surge: bubble of water carried by a hurricane, causing coastal flooding.
stratopause: the region between the stratosphere and the mesosphere.
stratosphere: the layer of the atmosphere above the troposphere; temperature increases with altitude.
stratus: layered, sheet-like clouds, usually associated with warm fronts and found at lower altitudes.
streak: the color of the powder left behind when a mineral is rubbed along an unglazed porcelain tile.
striations: parallel scratches on the Earth's surface caused by rocks dragged by a glacier; the scratches point in the direction of the glacial movement.
strike-slip fault: a fault where rock plates move horizontally to each other.
subducting plate: crustal plate which collides with another plate and moves under it.
sublimation: the rare process of a substance changing states from solid directly to a gas.
subsidence: land sinks into the sea; opposite of uplifting.
summer solstice: June 21, when the vertical ray of the Sun is at the Tropic of Cancer (23.5° N latitude), and is the longest day of the year in the Northern Hemisphere.
sunspot: cooler area on the surface of the Sun.
supercell: thunderstorm with strong updrafts that exist for hours and can spawn tornadoes.
supernova: the explosion of a star.
surplus: the period of time when the precipitation exceeds the needs for an area and the ground is saturated; runoff occurs, causing flooding conditions.
S-waves: secondary waves created by an earthquake; these shearing waves move at right angles to the path of travel and are stronger than P-waves, but only move through solids.
syncline: parallel rock layers folded downward in a valley-like formation.
talus: a pile of rocks at the bottom of a hill.
terminal moraine: a moraine created at the end of the advance of a glacier.
terrane: large pieces of rock that are moved large distances; can be from another plate.
terrestrial planet: inner planet (Mercury, Venus, Earth, and Mars) with a rocky surface.
thermocline: zone in water where the temperature changes drastically.
thermosphere: uppermost layer of the atmosphere; temperatures increase with altitude.
thin-skinned thrusting: thin, horizontal sheets of rock from the edge of a continent are forced inland.
till: an unsorted pile of sediment left behind when a glacier melts.
topographic map: map that shows elevations above sea level.
tornado: narrow, funnel-shaped column of wind created by a thunderstorm.
trace fossil: evidence that life existed in the past, such as footprints and burrows.
trade winds: planetary winds between 0° and 30° latitude.
transform plate boundary: region where plates move next to each other.
transparent: light can pass through the substance.
trench: a deep canyon in the ocean caused by a plate being subducted under another plate.
tropical depression: strong low-pressure system formed in low latitudes.
tropical storm: low-pressure system with sustained winds from 39 to 73 mph.
tropopause: region between the troposphere and the stratosphere.
troposphere: lowest level of the atmosphere, where weather occurs; temperature decreases with altitude.
True North: geographic North Pole, latitude 90° N.
tsunami: a large wave created by an underwater earthquake or landslide.
turbidity currents: undersea mudslides.
umbra: the darkest part of a shadow.
unconformity: a break or gap in the rock record where layers of rock have been eroded.
universal law of gravity: formula that measures the force of gravity; developed by Isaac Newton.
updraft: wind current moving upward in a cloud.
upwelling: deep ocean water is pulled to the surface by currents.
urban heat island effect: city areas are warmer than suburbs or rural areas due to less vegetation, more land coverage and other infrastructure.
usage: time in the water budget for an area when water is being used faster than it is being replenished.
valley glacier: a glacier located on top of a mountain, also called an alpine glacier, that moves downhill through the valley.
vaporization: the process of boiling.
varve: alternating layers of sediment showing yearly cycles.
vector: field quantity that measures magnitude and direction.
Vernal equinox: March 21, when the vertical ray of the Sun is at the Equator; the entire Earth has 12 hours of day and 12 hours of night.
vertical ray: radiational energy from the Sun that strikes the Earth at a right angle.
vesicular texture: rock that has gas pockets and air that was trapped during the rock's formation.
waning: part of the lunar cycle in which the Moon is getting less full and the "left side is lit up" (left side lit).
warm front: the leading edge of a warm air mass.
water table: the surface of the water in the zone of saturation.
waxing: part of the lunar cycle when the Moon is getting more full, and the "right side is lit up."
weathering: the physical or chemical breaking down of rocks due to exposure to the atmosphere.
wet-bulb depression: difference between wet-bulb and dry-bulb temperatures, used to find relative humidity and dew point temperatures.
white dwarf: final stage of a star as it collapses onto itself.
windward: the side facing the wind.
Winter solstice: December 21, when the vertical ray of the Sun is at the Tropic of Capricorn (23.5° S latitude), the shortest day of the year in the Northern Hemisphere.
zenith: the point directly overhead of an observer.
zone of accumulation: upper level of a glacier where more snow falls than melts.
zone of aeration: area underground above the water table where the spaces between rocks contain a mixture of air and water.
zone of saturation: area underground where the spaces between rock particles are filled with water.
