Glossary of Terms

Aquifer: An aquifer is an underground layer that contains groundwater.

Atmosphere: A unit of atmosphere measures the air pressure at sea level, which is about 14.7 pounds per square inch.

Cloud: A cloud is a visible mass of small water droplets or tiny ice crystals that are suspended in the atmosphere.

Condensation: Condensation is the process by which water vapor changes into liquid.

Cloud Condensation Nuclei: Water vapor surrounds tiny particles, condensing in clouds to become raindrops.

Current: Currents are predictable and steady flows of fluid in a larger body of fluid.

Density: Density describes the amount of things in a specific space.

Dew Point: Dew point is the temperature at which water in the air condenses to become water droplets near the ground.

Ecosystem: An ecosystem is a community of living and nonliving things in an area.

Erosion: Erosion happens when soil is worn away, usually by wind, water, or ice.

Evaporation: Evaporation is the process of water changing into water vapor.

Evapotranspiration: When moisture from the soil evaporates into the atmosphere or when transpiration from plants occurs, this is called evapotranspiration.

Fog: Clouds near the ground are known as fog.

Freshwater: A lake, river, or spring is a source of freshwater, which animals can drink. Unlike seawater, it does not contain salt.

Glacier: A glacier is a mass of ice that moves slowly across a land mass.

Great Lakes: The Great Lakes are the biggest freshwater bodies of water in the United States.

Greenhouse Gas: Gases in the atmosphere that absorb solar heat reflected by Earth’s surface, contributing to warming of the atmosphere, are greenhouse gases.

Groundwater: Groundwater is water found in an aquifer.

Humidity: The amount of water vapor in the air is the humidity.

Ice: Ice is water in solid form.

Ice Cap: An ice cap is an area of less than 19,000 square miles covered by ice.

Ice Sheet: Ice sheets are glacial ice areas that cover a large expanse.

Lake: A lake is a body of water that is surrounded by land.

Microscopic: Microscopic describes something very small.

Pollutant: A pollutant is a substance that harms a natural resource.

Precipitation: Precipitation includes all types of water that fall to Earth.

River: A river is a big stream of fresh water that flows.

Runoff: When fluid overflows from a farm or factory, it’s known as runoff.

Snowmelt: Melted water from snow is snowmelt.

Temperature: The level of heat or cold, measured by a thermometer, is temperature.

Transpiration: Water that evaporates from plants is transpiration.

Vapor: Vapor is liquid that is suspended in air.

Water Cycle: Water moves between the land, bodies of water, and atmosphere in a process known as the water cycle.

Weather: Weather describes the state of the atmosphere, and it includes atmospheric pressure, temperature, humidity, cloudiness, precipitation, and wind.

Wind: Wind is air that moves from areas of high pressure to low-pressure zones.