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Learn to recycle, reduce, reuse and revere with Environmental Resources from Gale

Words to Know

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Acid rain:
rain that is made more acidic by sulfuric and/or nitric acid in the air, due to the burning of fossil fuels.
Active volcano:
a volcano that continues to erupt regularly.
ground shaking that occurs after the main shock of an earthquake.
Air mass:
a large quantity of air throughout which temperature and moisture content is fairly constant.
Air pressure:
pressure exerted by the weight of air over a given area of Earth's surface. Also called atmospheric pressure or barometric pressure.
Mountain system composed of more than fifteen principle mountain ranges that extends in an arc for almost 660 miles (1,060 kilometers) across south-central Europe.
mountain range extending more than 5,000 miles (8,045 kilometers) along the western coast of South America.
instrument used to measure wind speed.
an underground layer of spongy rock, gravel, or sand in which water collects.
a climate in which almost no rain or snow falls.
very small, fine fragments of lava or rock that are blasted into the air during volcanic explosions.
a rocky chunk of matter in orbit around the sun.
region of the mantle below the lithosphere, composed of partially melted rock.
Avalanche wind:
a cloudlike mixture of snow particles and air pushed ahead of a slab avalanche as it races downward.
Avalanche path:
the course an avalanche takes down a slope, composed of a starting zone, a track, and a runout zone.


a small fire set by firefighters in the path of an oncoming wildfire to burn up the fuel before the main fire arrives, thus blocking it.
instrument used to measure air pressure.
a type of rock that forms from hardened lava.
the most severe type of winter storm, characterized by winds of 35 miles (56 kilometers) per hour or greater, large quantities of falling or blowing snow, and low temperatures.
Blocking system:
a whirling air mass containing either a high-pressure system (a blocking high) or a low-pressure system (a blocking low), that gets cut off from the main flow of upper-air westerlies.


a large depression, usually circular or oval shaped, left behind when a volcano's summit collapses.
a small piece of material thrown from a volcano during an eruption.
Cinder cone:
a volcano made of lava fragments.
the logging practice of harvesting all trees from vast forest tracts.
the weather experienced by a given location, averaged over several decades.
the heaviest type of rain, in which rain falls at a rate of 4 inches (10 centimeters) or more per hour.
the process by which an ice crystal grows larger. The ice crystal collides and sticks together with water droplets as the ice crystal travels through a cloud.
Coastal flood:
a flood that occurs along the coasts of a lake or ocean.
Cold front:
the line behind which a cold air mass is advancing, and in front of which a warm air mass is retreating.
a body in space that has a tail and follows an orbit around the sun.
Composite volcano:
a volcano with steep sides made of layers of lava and ash.
the sloping walls of a volcano (not all volcanoes have cones).
a small cone on the side of a large volcano.
Conservation tillage:
the practice of leaving vegetation on fields during idle periods to protect the soil from erosion and trap moisture.
Continental drift:
the geologic theory that all continents were originally part of a single landmass before they slowly separated and drifted apart.
the upward motion of a mass of air that has been heated. Convection is the primary way that heat is transferred in the atmosphere. It is the process by which warm air rises up from the ground, to be replaced by cold air. The cold air is then warmed and cycles upward.
Convection current:
circular movement of a gas or liquid between hot and cold areas.
Conventional radar:
instrument that detects the location, movement, and intensity of precipitation, and gives indications about the type of precipitation. It operates by emitting microwaves, which are reflected by precipitation. Also called radar.
the bowl-shaped area around the opening at the top of a volcano.
the highest point of a wave.
Crown fire:
a fire that spreads through the treetops, or crown, of a forest.
the outermost layer of Earth, varying in thickness from 3.5 miles (5 kilometers) to 50 miles (80 kilometers).
(pronounced cume-you-lo-NIM-bus) a tall, dark, ominous-looking cloud that produces thunderstorms. Also called thunderstorm cloud.
(pronounced SIGH-clone) the name for a hurricane that forms over the Indian Ocean.


a barrier built across a river or stream that blocks and controls the flow of water.
Debris avalanche:
a downward slide of loose, earthen material (soil, mud, and small rocks) that begins suddenly and travels at great speeds — similar to a snow avalanche. It builds into a fearsome mass of mud, trees, and rocks that can cause much damage.
the removal of all or most of the trees from a region.
a starry-shaped snowflake that has accumulated moisture and developed feathery branches on its arms. A dendrite is the most distinctive and most common type of snowflake.
the process by which water changes directly from a gas to a solid, without first going through the liquid phase.
Desert climate:
the world's driest climate type, with less than 10 inches (25.4 centimeters) of rainfall annually.
Desert pavement:
hard, flat, dry ground and gravel that remains after all sand and dust has been eroded from a surface.
the process by which semiarid lands turn to desert (also called land degradation). It is caused by prolonged drought, during which time the top layers of soil dry out and blow away.
Doppler radar:
a sophisticated type of radar that relies on the Doppler effect — the change in frequency of waves emitted from a moving source — to determine wind speed and direction, as well as the direction in which precipitation is moving.
Dormant volcano:
a volcano that has not erupted for many years.
downward blast of air from a thunderstorm cloud, felt at the surface as a cool gust.
(also called dropsonde) a device that is released at a high altitude by an aircraft in order to transmit atmospheric measurements to a radio receiver as it falls.
(pronounced DROWT) an extended period during which the amount of rain or snow that falls on an area is much lower than usual.
Dust Bowl:
the popular name for the approximately 150,000 square-mile-area (400,000-square-kilometer-area) in the southern portion of the Great Plains region of the United States. It is characterized by low annual rainfall, a shallow layer of topsoil, and high winds.
Dust devil:
a spinning vortex of sand and dust that is usually harmless but may grow quite large. Also called a whirlwind.
Dust storm:
a large cloud of dust blown by a strong wind.


a landslide that consists of material that is moist and full of clay, yet drier than the material in mudflows.
a sudden shifting of masses of rock beneath Earth's surface, which releases enormous amounts of energy and sends out shock waves that cause the ground to shake.
a community of plants and animals, including humans, and their physical surroundings.
Effusive eruption:
the type of eruption in which lava spills over the side of a crater.
the stream of rock and dust that is thrown upwards when a meteorite strikes a planet.
El Niño:
Spanish for "the Christ child," this is an extraordinarily strong episode (occurring every two to seven years) of the annual warming of the Pacific waters off the coast of Peru and Ecuador.
Electric vehicles:
vehicles that run on electric batteries and motors instead of gasoline-powered engines.
acronym for El Niño/Southern Oscillation, it describes the simultaneous warming of the waters in the eastern Pacific and the shifting pattern of air pressure between the eastern and western edges of the Pacific Ocean.
the point on Earth's surface directly above the focus of an earthquake, where seismic waves first appear.
the removal of soil by water or wind. This is especially harmful when the top layer of soil, called the topsoil, is stripped away, because this is the layer where plants grow.
the release of pressure that sends lava, rocks, ash, and gases out of a volcano.
Extinct volcano:
a volcano that is never expected to erupt again.
the calm circle of low-pressure that exists at the center of a hurricane.
Eye wall:
the region of a hurricane immediately surrounding the eye, and the strongest part of the storm. The eye wall is a loop of thunderstorm clouds that produce heavy rains and forceful winds.


Fair-weather waterspout:
relatively harmless waterspout that forms over water and arises either in conjunction with, or independently of, a severe thunderstorm. Also called nontornadic waterspout.
the downward motion of rock or soil through the air or along the surface of a steep slope.
crack in Earth's surface where two plates or sections of the crust push and slide in opposite directions against one another.
Fault creep:
slow, continuous movement of plates along a fault, allowing pressure to be released.
Fire line:
a strip of ground, cleared of all combustible material, that is dug by firefighters to stop the advance of a wildfire (also called control line).
Fire triangle:
the combination of three elements required for any fire: fuel, oxygen, and heat.
a specialized firefighter who parachutes to strategic locations from airplanes to battle wildfires.
also called a blowup, it is the most explosive and violent type of wildfire.
a crack in Earth's surface through which volcanic materials can escape.
Flash flood:
a sudden, intense, localized flooding caused by persistent, heavy rainfall or the failure of a levee or dam.
the overflow of water onto normally dry land.
nearly flat land adjacent to a river that is naturally subject to periodic flooding.
the underground starting place of an earthquake (also called the hypocenter).
(pronounced FANE) A warm, dry wind that flows down from the Alps onto the plains of Austria and Germany.
Food chain:
transfer of food energy from one organism to another. It begins with a plant species, which is eaten by an animal species; it continues with a second animal species, which eats the first, and so on.
ground shaking that occurs before the main shock of an earthquake.
Fossil fuels:
coal, oil, and natural gas — materials composed of the remains of plants or animals that covered Earth millions of years ago and are today burned for fuel.
the freezing of the skin.
Fujita Intensity Scale:
scale that measures tornado intensity, based on wind speed and the damage created.
a vent in Earth's surface that releases steam and other gases, but generally no lava.
Funnel cloud:
cone-shaped spinning column of air that hangs well below the base of a thunderstorm cloud


a scientist who studies the origin, history, and structure of Earth.
a regular spray of hot water and steam from underground into the air.
slowly flowing masses of ice created by years of snowfall and cold temperatures.
Global warming:
the theory that the average temperatures around the world have begun to rise, and will continue to rise, because of an increase of certain gases (called greenhouse gases) in Earth's atmosphere.
Global water budget:
the balance of the volume of water coming and going between the oceans, atmosphere, and continental landmasses.
Great Depression:
the worst economic collapse in the history of the modern world. It began with the stock market crash of 1929 and lasted through the late 1930s.
Greenhouse effect:
the warming of Earth due to the presence of certain gases in the atmosphere, which let sunlight come in but don't let heat go back out into space — as if Earth was covered with a big glass greenhouse that keeps everything warm.
Greenhouse gases:
gases that trap heat in the atmosphere. The most abundant greenhouse gases are water vapor and carbon dioxide. Others include methane, nitrous oxide, and chlorofluorocarbons.
Ground blizzard:
the drifting and blowing of snow that occurs after a snowfall has ended.
Ground fire:
a fire that burns beneath layer of dead plant material on the forest floor.


(pronounced huh-BOOB)a tumbling black wall of sand that has been stirred up by cold downdrafts along the leading edge of a thunderstorm or cold front. It occurs in north-central Africa and the southwestern United States.
(pronounced har-ma-TAHN)a mild, dry, and dusty wind that originates in the Sahara Desert.
Heat cramps:
muscle cramps or spasms, usually afflicting the abdomen or legs, caused by exercising in hot weather.
Heat exhaustion:
a form of mild shock that results when fluid and salt are lost through heavy perspiration.
Heat stroke:
a life-threatening condition that sets in when heat exhaustion is left untreated and the body has exhausted its efforts to cool itself. Also called sunstroke.
Heat wave:
an extended period of high heat and humidity.
Heavy snow:
snowfall that reduces visibility to 0.31 mile (0.5 kilometer) and yields, on average, 4 inches (10 centimeters) or more in a twelve-hour period or 6 inches (15 centimeters) or more in a twenty-four-hour period.
a snowflake in the shape of a long, six-sided column.
a specialized firefighter who ventures in to hazardous areas and spends long hours battling blazes.
Hot spot:
an area beneath Earth's crust where magma currents rise.
a storm made up of a series of tightly coiled bands of thunderstorm clouds, with a well-defined pattern of rotating winds and maximum sustained winds greater than 74 miles (119 kilometers) per hour.
Hybrid vehicles:
vehicles that run on more than one source of power, such as gasoline and electricity.
a condition characterized by a drop in core body temperature from the normal 98.6°F (37.3°C) to 95°F (35.3°C) or lower.


Igneous rock:
rock made of solidified molten material that made its way from the interior of the planet to the surface.
description of the physical damage caused by an earthquake.


Jet stream:
the world's fastest upper-air winds. Jet streams travel in a west-to-east direction, at speeds of 80 to 190 miles (130 to 300 kilometers) per hour, around 30,000 feet (9,150 meters) above the ground. Jet streams occur where the largest differences in air temperature and air pressure exist. In North America, jet streams are typically found over southern Canada and the northern United States, as well as over the southern United States and Mexico. The northern jet stream is called the polar jet stream, and the southern jet stream is called the subtropical jet stream.


(pronounced kahm-SENE)a hot, dry, southerly wind that originates on the Sahara and produces large sand and dust storms.


La Niña:
(pronounced el NEE-nya) a period of unusual cooling of the Pacific Ocean waters off the coast of Peru and Ecuador. It often follows an El Niño.
(pronounced LAH-hahr)a mudflow composed of volcanic ash and water that occurs in the wake of a volcanic eruption.
the movement of large amounts of soil, rocks, mud, and other debris downward and outward along a slope.
molten rock that erupts from a fissure or a vent (see magma).
Lava domes:
volcanic landmasses with bizarre shapes, made of hardened, thick, pasty layers of lava.
Lava tube:
a hollow tube formed when the outer layer of lava is cooled by the air and hardens; molten lava may continue running through the tube.
the side of a mountain facing the direction toward which the wind is blowing (in the United States, the eastern side). Cold air descends and produces dry conditions on this side.
a structure that raises the banks of a river; it increases the channel's water-holding capacity and makes it more difficult for water to overflow onto the surrounding land.
(pronounced li-quh-FAC-shun) the transformation of water-saturated soil into a liquidlike mass, usually by the action of seismic waves.
(pronounced LITH-os-fear) the rigid outermost region of Earth, composed of the crust and the upper part of the mantle.
Loose-snow avalanche:
avalanche composed of loosely packed snow that begins at a single point and slides down a slope, fanning out in the shape of an inverted "V."


molten rock containing dissolved gas and crystals that originates deep within Earth. When it reaches the surface it is called lava.
Magma chamber:
a reservoir of magma beneath Earth's surface.
the power of an earthquake.
thick, dense layer of rock that lies beneath Earth's crust. The mantle is about 1,800 miles (2,900 kilometers) thick and accounts for about 84 percent of the Earth's volume.
region of rotating updrafts created by wind shear within a supercell storm; it may be the beginnings of a tornado.
a chunk of rock and/or metal that has broken off a larger space object, such as an asteroid or a comet, and falls to Earth's surface.
the term that collectively describes all forms of meteoric material, including meteors and meteorites.
a scientist who studies weather and climate.
Modified Mercalli scale:
scale developed by Italian seismologist Giuseppe Mercalli to measure the intensity of an earthquake based on the amount of vibration felt by people and the extent of damage to buildings.
seasonal wind that blows from land to sea during the winter and from sea to land during the summer; also, more commonly, a seasonal period of heavy rainfall.
Monsoon climate:
a climate that is warm year-round with very rainy (flood-prone) summers and relatively dry winters. It encompasses much of southern and southeastern Asia, the Philippines, coastal regions of northern South America, and slices of central Africa.
a landslide consisting of soil mixed with water. It is wetter than the material in an earthflow.
Multi-vortex tornado:
tornado in which the vortex divides into several smaller vortices called suction vortices.


acronym for Next Generation Weather Radar, the network of 156 high-powered Doppler radar units that cover the continental United States, Alaska, Hawaii, Guam, and Korea.
a strong, northeasterly wind that brings cold air, often accompanied by heavy rain, snow, or sleet, to the coastal areas of New England and the mid-Atlantic states. Also called northeaster.
Numerical prediction model:
a computer program that mathematically duplicates conditions in nature. It is often used to predict the weather.


the study and exploration of the ocean.
a chemical reaction involving the combination of a material with oxygen.


the time between two successive waves.
a narrow passageway that leads from a magma reservoir to a vent.
a large section of Earth's crust.
Plate tectonics:
the geologic theory that Earth's crust is composed of rigid plates that "float" toward or away from each other, either directly or indirectly, creating the major geologic features on the planet's surface.
Plinian eruption:
a volcanic eruption that releases a deadly cloud of gas, dust, and ash.
Prescribed burn:
a planned, controlled fire that clears flammable debris from the forest floor.
Pressure gradient:
the rate at which air pressure decreases with horizontal distance.
a combination ax and hoe that is used by firefighters to clear brush and create a fire line. It was invented by forest ranger Edward Pulaski in 1903.
volcanic rock formed during the explosive eruption of magma; it has numerous gas bubbles and floats on water.
Pyroclastic flow:
a rapid flow of hot material consisting of ash, pumice, other rock fragments, and gas ejected by an explosive eruption.


an instrument package carried aloft on a small helium-filled or hydrogen-filled balloon. It measures temperature, air pressure, and relative humidity from the ground to a maximum altitude of about 19 miles (30.4 kilometers) above Earth's surface.
Rain gauge:
container that catches rain and measures the amount of rainfall.
the process of making or starting anew.
Richter scale:
the scale developed by American seismologist Charles Richter that describes the amount of energy released by an earthquake on a scale from 1 to 10. Each whole number increase in value on the scale indicates a 10-fold increase in the energy released. Earthquakes measuring 7 to 7.9 are major and those measuring 8 or above cause widespread destruction.
Ring of Fire:
the name given to the geologically active belt around the Pacific Ocean that is home to more than 75 percent of the world's volcanoes.
River flood:
the overflowing of the banks of a river or stream. It may be caused by excessive rain, the springtime melting of snow, blockage of water flow due to ice, or the failure of a dam or aqueduct.
River gauge:
a vertical measuring stick immersed in a river to measure changes in water level.
a cascade of rocks (of any size) down a steep slope at high speeds.


Saffir-Simpson Hurricane Damage Potential Scale:
the scale that ranks hurricanes according to their intensity, using the following criteria: air pressure at the eye of the storm, range of wind speeds, potential height of the storm surge, and the potential damage caused.
the wind-driven movement of particles along the ground and through the air.
containing the maximum amount of water a material can hold.
Sector plate:
a starry-shaped snowflake.
Seismic waves:
(pronounced SIZE-mic waves) vibrations that move outward from the focus of an earthquake, causing the ground to shake.
an instrument used to detect and measure seismic waves.
a climate in which very little rain or snow falls.
Severe blizzard:
a blizzard in which wind speeds exceed 45 miles (72 kilometers) per hour, snowfall is heavy, and the temperature is 10°F (-12°C) or lower.
Severe thunderstorm:
a thunderstorm that produces some combination of high winds, hail, flash floods, and tornadoes.
(pronounced shah-MALL)a hot, dry, dusty wind that blows for one to five days at a time, producing great dust storms throughout the Persian Gulf.
Shield volcano:
a volcano with long, gentle slopes, built primarily by lava flows.
(pronounced si-MOOM)a hot, dry, blustery, dust-laden wind that blows across the Sahara and the deserts of Israel, Syria, and the Arabian peninsula.
Slab avalanche:
avalanche that begins when fracture lines develop in a snowpack and a large surface plate breaks away, then crumbles into blocks as it falls down a slope.
the slow downhill movement of large portions (called blocks) of a slope. Each block rotates backward toward the slope in a series of curving movements.
Solar power:
power, usually in the form of electricity or heat, derived from the Sun's radiation.
(pronounced so-lih-FLUC-shun) the most rapid type of earthflow, occurring when snow or ice thaws or when earthquakes produce shocks that turn the soil into a fluid mass.
Southern Oscillation:
shifting patterns of air pressure at sea level, between eastern and western edges of the Pacific Ocean.
the starting of new fires, called spot fires, by sparks and embers that drift ahead of an advancing wildfire.
Steam eruption:
a violent eruption that occurs when water comes in contact with magma, rapidly turns to steam, and causes the mixture to explode.
Storm surge:
a wall of water, usually from the ocean, that sweeps onto shore when the eye of a hurricane passes overhead.
Storm tide:
the combined heights of the storm surge and the ocean tide. If a storm surge hits a shore at the same time as a high tide, it can significantly increase the amount of flooding and damage.
gloomy, gray, featureless sheets of clouds that cover the entire sky, at low levels of the atmosphere.
Subduction zone:
a region where two plates come together and the edge of one plate slides beneath the other.
Suction vortices:
small vortices within a single tornado that continually form and dissipate as the tornado moves along, creating the tornado's strongest surface winds.
Supercell storm:
the most destructive and long-lasting form of a severe thunderstorm, arising from a single, powerful convective cell. It is characterized by strong tornadoes, heavy rain, and hail the size of golfballs or larger.
Surface fire:
a fire with a visible flame that consumes plant material and debris on the forest floor.


Tidal station:
a floating instrument center in the ocean that records water levels.
Tornadic waterspout:
tornado that forms over land and travels over water. Tornadic waterspouts are relatively rare and are the most intense form of waterspouts.
rapidly spinning column of air that extends from a thunderstorm cloud to the ground. Also called twister.
Tornado cyclone:
spinning column of air that protrudes through the base of a thunderstorm cloud.
Tornado family:
a group of tornadoes that develops from a single thunderstorm.
Tornado outbreak:
emergence of a tornado family. Tornado outbreaks are responsible for the greatest amount of tornado-related damage.
Trade winds:
dominant surface winds near the equator, generally blowing from east to west and toward the equator.
the process by which plants emit water through tiny pores in the underside of their leaves.
Tropical cyclone:
any rotating weather system that forms over tropical waters.
Tropical depression:
the weakest form of tropical cyclone, characterized by rotating bands of clouds and thunderstorms with maximum sustained winds of 38 miles (61 kilometers) per hour or less.
Tropical disturbance:
a cluster of thunderstorms that is beginning to rotate.
Tropical storm:
a tropical cyclone weaker than a hurricane, with organized bands of rotating thunderstorms and maximum sustained winds of 39 to 73 miles (63 to 117 kilometers) per hour.
the lowest point of a wave.
(pronounced tsoo-NAH-mee)a series of giant ocean waves caused by a large displacement of water.
Tsunami warning:
an alert stating that a tsunami has been detected and is approaching the designated area. People are instructed to move to higher ground immediately.
Tsunami watch:
an alert stating that an earthquake has occurred in the Pacific region of sufficient magnitude to trigger a tsunami. People are instructed to listen for further news.
(pronounced TIE-foon)the name for a hurricane that forms over the western North Pacific and China Sea region.


Upper-air westerlies:
global-scale, upper-air winds that flow in waves heading west to east (but also shifting north and south) through the middle latitudes of the Northern Hemisphere.
the rising up of cold waters from the depths of the ocean, replacing the warm surface water that has moved away horizontally.


an opening in the surface of Earth through which molten rock, lava, ash, and gases escape.
an opening in Earth's surface through which gases, hot rocks, and ash are ejected from the heated inner portion of the planet.
(plural: vortices)vertical axis of extremely low pressure around which winds rotate.


Wall cloud:
a roughly circular, rotating cloud that protrudes from the base of a thunderstorm cloud; it is often the beginning of a tornado.
rapidly rotating column of air that forms over a large body of water, extending from the base of a cloud to the surface of the water.
Weather satellite:
a satellite equipped with infrared and visible imaging equipment that provides views of storms and continuously monitors weather conditions around the planet.
a condition in which falling, drifting, and blowing snow reduce visibility to almost zero.
a large, uncontrolled fire in grass, brush, or trees.
row of trees or shrubs placed in a farm field to slow the wind and keep it from blowing.
Wind chill factor:
the cooling effect on the body due to a combination of wind and temperature.
Wind power:
power, usually in the form of electricity, derived from the wind.
the side of a mountain facing the direction from which the wind is blowing (in the United States, the western side). Warm air ascends, forms clouds, and yields precipitation on this side.

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Source: Dangerous Planet. U·X·L, 2001.

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