Air Mass

A large body of air that takes on the climatic conditions of the area where it is formed.


The amount of energy reflected by a surface. Light surfaces tend to have a high albedo because they reflect more energy. Dark surfaces tend to have a low albedo because they absorb more energy.


An underground area of rock that stores groundwater. Humans often pump out groundwater from aquifers or use them as a source for wells.


Rocky celestial bodies left over from the formation of the solar system that are smaller than planets and orbit the Sun.

Big Bang Theory

Scientific theory for how the universe was created.

Black Hole

An area in space with extremely strong gravity from which no light can escape.


The border between two tectonic plates.


the ability or tendency to float in water or air or some other fluid


A path through which electricity can flow.


The typical weather conditions in an area over a 30-year period.

Climate Change

A significant change over a 30-year period from the typical or expected weather patterns of an area. Modern climate change is human-caused.


A frozen ball of gas, rock, and dust that orbit the Sun. When a comet gets close to the Sun, it heats up and the gas and dust form a tail.


Process by which water changes states from water vapor to liquid water.

Continental Drift

Theory that states that all of Earth's land was originally a united supercontinent that drifted apart over time. This theory was eventually replaced by the theory of plate tectonics.

Continental Plates

Less dense tectonic plates that make up the surface of land on Earth.

Convergent Boundary

Tectonic plates push into each other.


The innermost layers of Earth; made of a liquid outer core and a solid inner core.


Depression formed by an impact.


The outermost layer of Earth.


A flow of electrical charge


Process by which water vapor (gas) converts straight to solid form, resulting in snow.

Divergent Boundary

Tectonic plates pull apart from each other.


An interconnected community of all the living organisms and the physical landscape of an area.


The movement of electrons from one atom to another creating a flow of electrical charge


The day when there is an equal amount of day and night (12 hours each). Occurs when the Sun shines directly on the Equator.


Process by which broken down rocks are carried to a new location.


Process by which water changes states from liquid to gaseous water vapor.


Process by which water evaporates from the surface of the land or from plant's leaves.


Break or crack in the plates on Earth's crust.

Fossil Fuels

Finite sources of energy derived from ancient remains of decomposing organisms. The main fossil fuels are coal, oil, and natural gas.


a force that holds back the motion of a sliding object


A collection of billions of stars, gas, and dust held together by gravity in space.


The theory that Earth is at the center of our solar system, and the Sun and other planets revolve around it.


a rock containing a cavity lined with crystals or other mineral matter

Geomagnetic Poles

North and south axes of Earth's magnetic field


Large body of snow and ice that moves slowly across land.

Glacier Retreat

When glaciers melt at a faster rate than snow falls to rebuild the glacier's mass.

Greenhouse Gas

An asymmetrical gas in Earth's atmosphere that traps heat. The main greenhouse gases are carbon dioxide, nitrous oxide, methane, and water vapor.

Hardiness Zones

A way of indicating which plants will grow best in an area based on the average temperature.


The theory that the Sun is at the center of our solar system.

High Pressure System

Air pressure on Earth is higher than normal, so air descends. A high pressure system is associated with good weather--sunny and clear skies.

Hot Spot

An extremely hot area located in the center of a tectonic plate where magma can rise to the surface. Some volcanoes are located over hot spots, rather than at tectonic plate boundaries.


An object's tendency to resist changes in motion.


The process by which surface water soaks into the ground.

Island Arc

A chain of islands in the ocean in an arc shape. Formed by two convergent oceanic plates and volcanic eruptions.

Jet Stream

A large current of wind which carries warm and cold air masses to different areas of Earth.

Kinetic Energy

The energy of an object due to motion.


A location's distance from the Equator.

Law of Original Horizontality

Due to the pull of gravity, new rock is initially formed in flat, horizontal layers.

Law of Superposition

Deeper layers of rocks are older than layers closer to the surface.


Part of Earth made of the crust and the upper molten part of the mantle.

Low Pressure System

Air pressure on Earth is lower than normal, so air rises. A low pressure system is associated with bad weather--clouds, rain, and wind.


Molten rock beneath Earth's surface.


An object or material that produces its own magnetic field

Magnetic Field

The area around a magnet that has magnetic force


A force that attracts or repels objects that contain magnetic material


The middle layer of Earth between the crust and the core.


The streak of light that is caused when a meteoroid enters Earth’s atmosphere and burns up due to friction. Also known as a shooting star.


A meteoroid that survives its trip through the atmosphere and lands somewhere on Earth. The impact of a meteorite can cause a crater on the surface of a planet.


A small rock in space that orbits around the Sun. Most meteoroids have broken off of larger objects such as asteroids or comets. They can be as small as a grain of sand or as large as a pickup truck.

Mid-Ocean Ridge

An underwater chain of mountains formed at a divergent plate boundary.


A cloud of gas and dust in space.

Nuclear Fusion

The process by which stars get their energy. Atoms fuse together creating a nuclear reaction which releases energy in the form of heat and light in the star.

Oceanic Plates

Denser tectonic plates that make up the ocean floor on Earth.


A supercontinent made of all of Earth's landmass that existed 200-250 million years ago.

Parallel Circuit

A circuit where electricity flows through multiple paths


The time it takes a pendulum to swing across and back to its original starting point.

Plane of the Ecliptic

The disk-shaped plane in which everything in our solar system orbits around the Sun.

Plate Tectonics

Theory that Earth's crust is divided into many pieces, called tectonic plates, which move over time due to convection currents in the mantle.

Positive Feedback Loop

A process where one change triggers the next in a continuous cycle that encourages the initial change.

Potential Energy

The energy held by an object that gives it capacity to do work.


Parts per million; a unit of measurement for carbon dioxide and other gases in the atmosphere.


Heavier water droplets condense and fall from clouds to Earth's surface in the form of rain, snow, or hail.


force applied over an area

Rain Shadow

A desert area that is created when a mountain blocks precipitation from passing to one side.

Red Giant

Phase in a star's life cycle where it greatly increases in size as it burns fuel through nuclear fusion.

Ring of Fire

An area in the Pacific Ocean bounded by several tectonic plates. Due to tectonic activity along these plates, this area has a high number of earthquakes and volcanic eruptions.

Series Circuit

A circuit where electricity flows through one continuous path

Snowball Earth

A period of extreme glaciation where a positive feedback loop led to Earth being covered almost entirely by ice.

Solar System

Our Sun and all of the planets and other bodies in space (comets, asteroids, meteoroids) that orbit around the Sun in the plane of the ecliptic.


When two tectonic plates converge, the denser plate is pushed under the other.

Subduction Zone

The boundary between two convergent tectonic plates where one plate subducts under the other.


Process by which water changes straight from its solid state to gas. This is the same process that occurs with dry ice--when exposed to air, carbon dioxide is released in the form of gas through sublimation.

Summer Solstice

The day with the most sunlight. In the Northern Hemisphere this occurs when the Sun shines directly on the Tropic of Cancer.


The giant explosion of a supermassive star at the end of its life cycle.

Thermal Expansion

An increase in the volume of matter when its temperature increases.

As global temperature increases, ocean water heats and expands which contributes to sea level rise.

Tipping Point

A place of irreversible damage where abnormal and extreme climate change conditions become the norm.


The physical features of an area of land.

Transform Boundary

Tectonic plates sideswipe each other.


A long depression formed on the ocean floor from the convergence of two oceanic plates. Trenches are some of the deepest place on Earth's surface.


A vent that allows magma, rock fragments, ash, and gases to escape to the surface of a planet or moon.

Water Cycle

Process of how water in different states continuously moves on, above, and below Earth's surface. 


The short term atmospheric conditions in an area.


The breakdown of rocks on Earth's surface

Winter Solstice

The day with the least of sunlight. In the Northern Hemisphere this occurs when the Sun shines directly on the Tropic of Capricorn.