7th Grade: Hydrologic Cycle
Vocabulary
Hydrologic Cycle (Water cycle)- continuous movement of water from the oceans and
freshwater sources to the air and land and finally back to the oceans; also called the
hydrologic cycle
Evaporation- process by which energy from the sun causes water on the surface of the
Earth to change to water vapor, the gas phase of water; first step of the water cycle
Condensation- process by which water vapor changes back into a liquid; second step of
the water cycle
Precipitation- process by which water returns to the Earth in the form of rain, snow, sleet,
or hail; third step of the water cycle
Groundwater- water that soaks into the ground and remains in the ground
Surface runoff- water that enters a river or stream after a heavy rain or during a spring
thaw of snow or ice
Pore space- space between particles of soil
Watershed- land area in which surface runoff drains into a river or a system of rivers and
streams
Reservoir- artificial lake used as a source of fresh water
Permeable- term used to describe material through which water can move quickly
Impermeable- term used to describe material through which water cannot move quickly;
opposite of permeable
Zone of saturation- underground region in which all the pores are filled with water
Zone of aeration- relatively dry underground region in which the pores are filled mostly
with air
Water table- surface between the zone of saturation and the zone of aeration that marks
the level below which the ground is saturated, or soaked with water
Aquifer- layer of rock or sediment that allows ground water to pass freely