When Mount St. Helens, in the U.S. state of Washington, erupted in 1980, a column of ash from the volcano rose 19 kilometers (12 miles) into the air.
harsh or rough.
to soak up.
transported by air currents.
vehicle able to travel and operate above the ground.
person who monitors the position, speed, and direction of different aircraft to ensure safe and efficient air travel.
layers of gases surrounding a planet or other celestial body.
large mass of snow and other material suddenly and quickly tumbling down a mountain.
the art and science of creating and operating aircraft.
to connect or stick together.
to stop a planned event.
hard material used as a building material or a binding agent for stronger building materials such as concrete.
to describe the characteristics of something.
to give as an example.
rough or composed of large, jagged particles.
edge of land along the sea or other large body of water.
to fall apart completely.
sharing of information and ideas.
device designed to access data, perform prescribed tasks at high speed, and display the results.
to work together or organize for a specific goal.
expensive or having a lot of value.
harm that reduces usefulness or value.
to argue or disagree in a formal setting.
remains of something broken or destroyed; waste, or garbage.
to put out of shape or distort.
to place or deliver an item in a different area than it originated.
harmful condition of a body part or organ.
to systematically send off.
to scatter or spread widely.
to break up or disintegrate.
severe or extreme.
tiny, dry particles of material solid enough for wind to carry.
community and interactions of living and nonliving things in an area.
performing a task with skill and minimal waste.
to get rid of or throw out.
set of physical phenomena associated with the presence and flow of electric charge.
sudden, unplanned event that requires immediate action.
capacity to do work.
machine that converts energy into power or motion.
tools and materials to perform a task or function.
to wear away.
to grow or get larger.
material that can quickly and violently expand due to a chemical change.
an extreme shortage of food in one area during a long period of time.
piece or part.
system or order of a nation, state, or other political unit.
horizontal and vertical lines used to locate objects in relation to one another on a map.
disease or sickness.
activity that produces goods and services.
pain, tenderness, and disturbed function of an area of the body.
structures and facilities necessary for the functioning of a society, such as roads.
to breathe in.
to slow or prevent.
site where garbage is layered with dirt and other absorbing material to prevent contamination of the surrounding land or water.
molten rock, or magma, that erupts from volcanoes or fissures in the Earth's surface.
sudden electrical discharge from clouds.
state of matter with no fixed shape and molecules that remain loosely bound with each other.
organ in an animal that is necessary for breathing.
mechanical appliances or tools used in manufacturing.
molten, or partially melted, rock beneath the Earth's surface.
underground reservoir that holds molten rock.
very large or heavy.
threatening or perceived as harmful.
inorganic material that has a characteristic chemical composition and specific crystal structure.
solid material turned to liquid by heat.
landmass that forms as tectonic plates interact with each other.
area of land set aside for recreational use.
large plateau in southern South America, stretching from the Andes Mountains to the Atlantic Ocean.
an unusual act or occurrence.
single, upward flow of a fluid, such as water or smoke.
solid substance reduced to fine, loose particles.
ability to do work.
action taken to avoid a negative outcome or event.
method or steps followed to achieve a goal.
to push forward.
people of a community.
current of volcanic ash, lava, and gas that flows from a volcano.
to destroy completely, especially by tearing down.
to rebound or return light from a surface.
any area on Earth with one or more common characteristics. Regions are the basic units of geography.
natural substance composed of solid mineral matter.
small, loose grains of disintegrated rocks.
process of removing harmful pollutants and contaminants from water discarded by homes and businesses, so the water is safe for most uses.
utter and unmixed with anything else.
liquid waste, such as that from the coal mining and cleaning process, also called slurry.
light and heat from the sun.
to make solid.
to cause to slow or come to a stop.
level of Earth's atmosphere, extending from 10 kilometers (6 miles) to 50 kilometers (31 miles) above the surface of the Earth.
to be unable to breathe.
degree of hotness or coldness measured by a thermometer with a numerical scale.
solid material ejected from a volcano during an eruption.
to make a loud, deep noise.
movement of many things, often vehicles, in a specific area.
weather pattern of swirling winds over a center of low pressure above warm ocean waters. Tropical storms are less powerful than cyclones and hurricanes.
machine that captures the energy of a moving fluid, such as air or water.
one of a kind.
strong, destructive force.
the ability to see or be seen with the unaided eye. Also called visual range.
fragments of lava less than 2 millimeters across.
activity that includes a discharge of gas, ash, or lava from a volcano.
hard, brittle substance produced by lava cooling very quickly.
bolts of electricity produced in a volcanic plume. Also called a dirty thunderstorm.
drop in global temperatures due to volcanic debris in the atmosphere blocking the sun.
an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.
repeating or predictable changes in the Earth's atmosphere, such as winds, precipitation, and temperatures.
movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.
hard material that makes up the trunk and branches of trees and shrubs.
to inflict or bring about something painful.