Hydrologic Cycle
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Hydrologic Cycle

Hydrologic Cycle

The water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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describes how water is exchanged (cycled) through Earth's land, ocean, and atmosphere.

Grades

2 - 8

Subjects

Earth Science, Meteorology, Geography, Physical Geography, Geology

geology : The study of the natural features and processes of the Earth.

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The water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

describes how water is exchanged (cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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d) through Earth's land, ocean, and atmosphere. Water always exists in all three phases, and in many forms—as lakes

Great Lakes : A group of five large freshwater lakes located on the border between the United States and Canada, formed by glacial activity.

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Lake Huron : One of the five Great Lakes of North America, located between the United States and Canada.

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Lake Superior : The largest and northernmost of the Great Lakes, known for its cold waters and large surface area.

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and rivers , glaciers

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

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and ice sheet

ice sheet : A large mass of glacial ice and snow that covers a large area of land for a long period of time.

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glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

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ice cap : An area of fewer than 50,000 square kilometers (19,000 square miles) covered by ice.

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s
, oceans and seas, underground aquifers

aquifer : An underground layer of water-bearing rock or materials like gravel, sand, or silt, from which groundwater can be extracted.

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aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

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, and vapor

impact of evaporation and condensation : Evaporation absorbs energy and cools the environment, while condensation releases energy and warms it, affecting local weather conditions.

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evaporation : The process by which water changes from a liquid to a gas or vapor.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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in the air and clouds

clouds : Visible masses of tiny water droplets or ice crystals suspended in the atmosphere.

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cloud : A visible mass of tiny water droplets or ice crystals suspended in the Earth's atmosphere.

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.

Evaporation, Condensation, and Precipitation

The water cycle consists of three major processes: evaporation, condensation, and precipitation

precipitation : All forms in which water falls to Earth from the atmosphere, including rain, snow, sleet, and hail.

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water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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.

Evaporation

Evaporation is the process of

impact of evaporation and condensation : Evaporation absorbs energy and cools the environment, while condensation releases energy and warms it, affecting local weather conditions.

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evaporation : The process by which water changes from a liquid to a gas or vapor.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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a liquid's surface changing to a gas. In the water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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, liquid water (in the ocean, lakes, or rivers) evaporates and becomes water vapor.

Water vapor

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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surrounds us, as an important part of the air we breathe. Water vapor is also an important greenhouse

greenhouse gases : Gases in Earth's atmosphere, such as carbon dioxide and water vapor, that trap heat and contribute to the greenhouse effect, warming the planet.

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gas
. Greenhouse gases such as water vapor

greenhouse gases : Gases in Earth's atmosphere, such as carbon dioxide and water vapor, that trap heat and contribute to the greenhouse effect, warming the planet.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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and carbon dioxide insulate Earth and keep the planet warm enough to maintain life as we know it. Increasing amounts of greenhouse gases

greenhouse gases : Gases in Earth's atmosphere, such as carbon dioxide and water vapor, that trap heat and contribute to the greenhouse effect, warming the planet.

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in the atmosphere also contribute to global warming.

The water cycle's evaporation

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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evaporation : The process by which water changes from a liquid to a gas or vapor.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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process is driven by the sun. As the sun interacts with liquid water on the surface of the ocean, the water becomes an invisible gas (water vapor). Evaporation

impact of evaporation and condensation : Evaporation absorbs energy and cools the environment, while condensation releases energy and warms it, affecting local weather conditions.

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is also influenced by wind

wind : The movement of air from a high-pressure zone to a low-pressure zone, caused by the uneven heating of the Earth by the sun.

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, temperature

temperature : The degree of hotness or coldness measured by a thermometer with a numerical scale, indicating thermal energy.

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weather : The state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness, at a specific time and place.

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, and the density of the body of water.

Condensation

Condensation

Condensation : Condensation is the process where water vapor in the atmosphere cools and changes back into liquid water, forming clouds.

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is the process of a gas changing to a liquid. In the water cycle, water vapor

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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in the atmosphere condenses and becomes liquid.

Condensation

Condensation : Condensation is the process where water vapor in the atmosphere cools and changes back into liquid water, forming clouds.

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can happen high in the atmosphere or at ground level. Clouds form as water vapor

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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clouds : Visible masses of tiny water droplets or ice crystals suspended in the atmosphere.

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cloud : A visible mass of tiny water droplets or ice crystals suspended in the Earth's atmosphere.

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condenses, or becomes more concentrated (dense). Water vapor condenses around tiny particles called cloud condensation nuclei (CC

Condensation : Condensation is the process where water vapor in the atmosphere cools and changes back into liquid water, forming clouds.

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Cloud Condensation Nuclei (CCN) : Cloud condensation nuclei are tiny particles around which water vapor condenses to form clouds.

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cloud : A visible mass of tiny water droplets or ice crystals suspended in the Earth's atmosphere.

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N)
. CCN can be specks of dust, salt, or pollutant

pollutant : A chemical or other substance that harms a natural resource, often introduced into the environment by human activity.

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s
. Clouds

clouds : Visible masses of tiny water droplets or ice crystals suspended in the atmosphere.

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cloud : A visible mass of tiny water droplets or ice crystals suspended in the Earth's atmosphere.

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at ground level are called fog

Fog : Fog is a suspension of tiny water droplets in the air near the ground, not dense enough to precipitate.

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or mist.

Like evaporation, condensation

impact of evaporation and condensation : Evaporation absorbs energy and cools the environment, while condensation releases energy and warms it, affecting local weather conditions.

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evaporation : The process by which water changes from a liquid to a gas or vapor.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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Condensation : Condensation is the process where water vapor in the atmosphere cools and changes back into liquid water, forming clouds.

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is also influenced by the sun. As water vapor cools, it reaches its saturation limit, or dew point

dew point : The temperature at which air becomes saturated with moisture and dew forms, indicating the amount of moisture in the air.

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. Air pressure is also an important influence on the dew point

dew point : The temperature at which air becomes saturated with moisture and dew forms, indicating the amount of moisture in the air.

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of an area.

Precipitation

As is the case with evaporation and condensation, precipitation

precipitation : All forms in which water falls to Earth from the atmosphere, including rain, snow, sleet, and hail.

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impact of evaporation and condensation : Evaporation absorbs energy and cools the environment, while condensation releases energy and warms it, affecting local weather conditions.

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evaporation : The process by which water changes from a liquid to a gas or vapor.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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is a process. Precipitation describes any liquid or solid water that falls to Earth as a result of condensation in the atmosphere. Precipitation includes rain, snow, and hail.

Fog is not precipitation

precipitation : All forms in which water falls to Earth from the atmosphere, including rain, snow, sleet, and hail.

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Fog : Fog is a suspension of tiny water droplets in the air near the ground, not dense enough to precipitate.

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. The water in fog does not condense sufficiently to precipitate, or liquefy and fall to Earth. Fog and mist are a part of the water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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called suspensions: They are liquid water suspended in the atmosphere.

Precipitation is one of many ways water is cycle

precipitation : All forms in which water falls to Earth from the atmosphere, including rain, snow, sleet, and hail.

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water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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d from the atmosphere to the earth or ocean.

Other Processes

Evaporation, condensation, and precipitation are important parts of the water cycle

precipitation : All forms in which water falls to Earth from the atmosphere, including rain, snow, sleet, and hail.

Image_precipitation_0.png

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

impact of evaporation and condensation : Evaporation absorbs energy and cools the environment, while condensation releases energy and warms it, affecting local weather conditions.

Image_impact-of-evaporation-and-condensation_0.png

evaporation : The process by which water changes from a liquid to a gas or vapor.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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. However, they are not the only ones.

Runoff

runoff : Overflow of fluid from a farm or industrial factory that can carry pollutants into natural water bodies.

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, for instance, describes a variety of ways liquid water moves across land. Snowmelt

snowmelt : The runoff produced by melting snow, which can contribute to river flow and groundwater recharge.

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, for example, is an important type of runoff produced as snow or glaciers

runoff : Overflow of fluid from a farm or industrial factory that can carry pollutants into natural water bodies.

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glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

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melt and form streams or pools.

Transpiration

evapotranspiration : The combined process of water evaporation from the Earth's surface and transpiration from plants, contributing to the water cycle.

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transpiration : The process by which plants release water vapor into the air through stomata in their leaves.

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is another important part of the water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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. Transpiration is the process of water vapor

transpiration : The process by which plants release water vapor into the air through stomata in their leaves.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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being released from plants and soil. Plants release water vapor through microscopic  pores called stomata

stomata : Tiny openings on the surface of leaves that control the exchange of gases in a plant, crucial for photosynthesis and respiration.

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. The opening of stomata is strongly influenced by light, and so is often associated with the sun and the process of evaporation

stomata : Tiny openings on the surface of leaves that control the exchange of gases in a plant, crucial for photosynthesis and respiration.

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evaporation : The process by which water changes from a liquid to a gas or vapor.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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. Evapotranspiration

evapotranspiration : The combined process of water evaporation from the Earth's surface and transpiration from plants, contributing to the water cycle.

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transpiration : The process by which plants release water vapor into the air through stomata in their leaves.

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is the combined components of evaporation and transpiration

evaporation : The process by which water changes from a liquid to a gas or vapor.

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transpiration : The process by which plants release water vapor into the air through stomata in their leaves.

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vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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, and is sometimes used to evaluate the movement of water in the atmosphere.

States of Water

Through the water cycle, water continually circulates through three states: solid, liquid, and vapor

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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.

Ice

ice sheet : A large mass of glacial ice and snow that covers a large area of land for a long period of time.

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glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

Image_glacial-ice_0.png

ice cap : An area of fewer than 50,000 square kilometers (19,000 square miles) covered by ice.

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is solid water. Most of Earth's fresh water is ice, locked in massive glaciers, ice sheet

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

Image_glaciers_0.png

ice sheet : A large mass of glacial ice and snow that covers a large area of land for a long period of time.

Image_ice-sheet_0.png

glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

Image_glacial-ice_0.png

s, and ice cap

ice sheet : A large mass of glacial ice and snow that covers a large area of land for a long period of time.

Image_ice-sheet_0.png

ice cap : An area of fewer than 50,000 square kilometers (19,000 square miles) covered by ice.

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s
.

As ice melts, it turns to liquid. The ocea

aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

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n, la

aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

Image_aquifers_0.png

kes, rivers, a

aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

Image_aquifers_0.png

nd underground a

aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

Image_aquifers_0.png

quifers a

aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

Image_aquifers_0.png

ll hold liquid wa

aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

Image_aquifers_0.png

ter.

Water vapor

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

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is an invisible gas. Water vapor is not evenly distributed across the atmosphere. Above the ocean, water vapor is much more abundant, making up as much as four percent

Four percent water vapor : Water vapor can make up as much as four percent of the air above the ocean, indicating high humidity.

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of the air. Above isolated deserts, it can be less than one percent.

The Water Cycle and Climate

The water cycle has a dramatic influence on Earth's climate

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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climate : All weather conditions for a given location over a period of time.

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 and ecosystem

ecosystem : A community of living organisms in conjunction with the nonliving components of their environment, interacting as a system.

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aquatic ecosystem : An ecosystem located in a body of water, such as a lake, river, or spring, where organisms interact with each other and their environment.

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s
.

Climate

climate : All weather conditions for a given location over a period of time.

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is all the weather

precipitation : All forms in which water falls to Earth from the atmosphere, including rain, snow, sleet, and hail.

Image_precipitation_0.png

temperature : The degree of hotness or coldness measured by a thermometer with a numerical scale, indicating thermal energy.

Image_temperature_0.png

weather : The state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness, at a specific time and place.

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climate : All weather conditions for a given location over a period of time.

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conditions of an area, evaluated over a period of time. Two weather conditions that contribute to climate

weather : The state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness, at a specific time and place.

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climate : All weather conditions for a given location over a period of time.

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include humidity

Humidity : Humidity is the amount of water vapor present in the air, affecting climate and weather patterns.

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and temperature

temperature : The degree of hotness or coldness measured by a thermometer with a numerical scale, indicating thermal energy.

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. These weather conditions are influenced by the water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

weather : The state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness, at a specific time and place.

Image_weather_0.png

.

Humidity is simply the amount of water vapor

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

Image_vapor_0.png

Humidity : Humidity is the amount of water vapor present in the air, affecting climate and weather patterns.

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in the air. As water vapor is not evenly distributed by the water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

, some regions experience higher humidity than others. This contributes to radically different climate

climate : All weather conditions for a given location over a period of time.

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s. Islands or coastal regions, where water vapor makes up more of the atmosphere, are usually much more humid than inland regions, where water vapor is scarcer.

A region's temperature also relies on the water cycle

temperature : The degree of hotness or coldness measured by a thermometer with a numerical scale, indicating thermal energy.

Image_temperature_0.png

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

. Through the water cycle, heat is exchanged and temperatures fluctuate . As wa

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

Image_vapor_0.png

ter evaporates, for example, it absorbs energy and cools the local environment. As water condenses, it releases energy and warms the local environment.

The Water Cycle and the Landscape

The water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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also influences the physical geography of Earth. Glacial

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

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glacial erratics : Large boulders transported and deposited by glaciers, often found far from their source, indicating past glacial movement.

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glacial depression : A depression in the Earth's surface formed by the movement of glaciers.

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Glacial Retreat : Glacial retreat is the process where glaciers melt faster than they are replenished by precipitation, reducing the amount of fresh water available.

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Fastest rate of glacial retreat : We are currently experiencing the fastest rate of glacial retreat in recorded history, impacting fresh water availability.

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glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

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melt and erosion

erosion : The process by which natural forces like water, wind, or ice wear away rocks and soil, often leading to the formation of new landforms.

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Chemical Erosion : Chemical erosion occurs when a rock’s chemical composition changes, such as when iron rusts or limestone dissolves due to carbonation.

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caused by water are two of the ways the water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

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helps create Earth's physical features.

As glaciers

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

Image_glaciers_0.png

slowly expand across a landscape, they can carve away entire valleys , create mountain peaks, and leave behind rubble as big as boulders. Yosemite Valley

Yosemite Valley : A glacial valley in Yosemite National Park, California, known for its stunning granite cliffs and natural beauty.

Image_yosemite-valley_0.png

, part of Yosemite National Park in the U.S. state of California, is a glacial

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

Image_glaciers_0.png

glacial erratics : Large boulders transported and deposited by glaciers, often found far from their source, indicating past glacial movement.

Image_glacial-erratics_0.png

glacial depression : A depression in the Earth's surface formed by the movement of glaciers.

Image_glacial-depression_0.png

Glacial Retreat : Glacial retreat is the process where glaciers melt faster than they are replenished by precipitation, reducing the amount of fresh water available.

Image_glacial-retreat_0.png

glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

Image_glacial-ice_0.png

valley
. The famous Matterhorn, a peak on the Alps between Switzerland and Italy, was carved as glaciers

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

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Matterhorn : A famous mountain peak in the Alps, located on the border between Switzerland and Italy, known for its distinctive shape.

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collided and squeezed up the earth between them. Canada's "Big Rock

Big Rock : A large glacial erratic located in Alberta, Canada, known for its size and geological significance.

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" is one of the world's largest " glacial erratics

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

Image_glaciers_0.png

glacial erratics : Large boulders transported and deposited by glaciers, often found far from their source, indicating past glacial movement.

Image_glacial-erratics_0.png

glacial depression : A depression in the Earth's surface formed by the movement of glaciers.

Image_glacial-depression_0.png

Glacial Retreat : Glacial retreat is the process where glaciers melt faster than they are replenished by precipitation, reducing the amount of fresh water available.

Image_glacial-retreat_0.png

Fastest rate of glacial retreat : We are currently experiencing the fastest rate of glacial retreat in recorded history, impacting fresh water availability.

Image_fastest-rate-of-glacial-retreat_0.png

glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

Image_glacial-ice_0.png

," boulders left behind as a glacier advances or retreats.

Glacial

glacial erratics : Large boulders transported and deposited by glaciers, often found far from their source, indicating past glacial movement.

Image_glacial-erratics_0.png

glacial depression : A depression in the Earth's surface formed by the movement of glaciers.

Image_glacial-depression_0.png

Glacial Retreat : Glacial retreat is the process where glaciers melt faster than they are replenished by precipitation, reducing the amount of fresh water available.

Image_glacial-retreat_0.png

glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

Image_glacial-ice_0.png

melt can also create landforms . The Great Lakes

Great Lakes : A group of five large freshwater lakes located on the border between the United States and Canada, formed by glacial activity.

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, for example, are part of the landscape of the Midwest

Midwest : A region of the United States that includes states such as Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.

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of the United States and Canada. The Great Lakes were created as an enormous ice sheet

Great Lakes : A group of five large freshwater lakes located on the border between the United States and Canada, formed by glacial activity.

Image_great-lakes_0.png

ice sheet : A large mass of glacial ice and snow that covers a large area of land for a long period of time.

Image_ice-sheet_0.png

melted and retreated, leaving liquid pools.

The process of erosion and the movement of runoff

runoff : Overflow of fluid from a farm or industrial factory that can carry pollutants into natural water bodies.

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erosion : The process by which natural forces like water, wind, or ice wear away rocks and soil, often leading to the formation of new landforms.

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also create varied landscapes across Earth's surface. Erosion is the process by which earth is worn away by liquid water, wind

wind : The movement of air from a high-pressure zone to a low-pressure zone, caused by the uneven heating of the Earth by the sun.

Image_wind_0.png

, or ice.

Erosion can include the movement of runoff

runoff : Overflow of fluid from a farm or industrial factory that can carry pollutants into natural water bodies.

Image_runoff_0.png

erosion : The process by which natural forces like water, wind, or ice wear away rocks and soil, often leading to the formation of new landforms.

Image_erosion_0.png

. The flow of water can help carve enormous canyons, for example. These canyons can be carved by rivers on high plateaus (such as the Grand Canyon, on the Colorado

Grand Canyon : A massive canyon carved by the Colorado River, located in the U.S. state of Arizona, known for its size and geological significance.

Image_grand-canyon_0.png

Colorado Plateau : A large plateau in the southwestern United States, known for its high elevation and unique geological features, including the Grand Canyon.

Image_colorado-plateau_0.png

Plateau in the U.S. state of Arizona). They can also be carved by currents deep in the ocean (such as the Monterey Canyon

Monterey Canyon : An underwater canyon located in the Pacific Ocean off the coast of California, known for its depth and marine biodiversity.

Image_monterey-canyon_0.png

, in the Pacific Ocean off the coast of the U.S. state of California).

Reservoirs and Residence Time

Reservoirs are simply where water exists at any point in the water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

. A

aquifer : An underground layer of water-bearing rock or materials like gravel, sand, or silt, from which groundwater can be extracted.

Image_aquifer_0.png

aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

Image_aquifers_0.png

n underground aquifer can store liquid water, for example. The ocean is a reservoir. Ice sheet

ice sheet : A large mass of glacial ice and snow that covers a large area of land for a long period of time.

Image_ice-sheet_0.png

s are reservoirs. The atmosphere itself is a reservoir of water vapor

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

Image_vapor_0.png

.

Residence time is the amount of time a water molecule spends in

residence time : The amount of time a water molecule spends in one place in the water cycle, such as in a river, ocean, or atmosphere.

Image_residence-time_0.png

residence time in the ocean : Water in the ocean has a residence time of about 3,200 years, reflecting the time it takes for water to circulate through the oceanic system.

Image_residence-time-in-the-ocean_0.png

residence time in the atmosphere : Water in the atmosphere has the shortest residence time of about nine days, highlighting the rapid turnover of water vapor in the air.

Image_residence-time-in-the-atmosphere_0.png

one reservoir. For instance, the residence time of "fossil water," ancient g

aquifers : Underground layers of water-bearing rock from which groundwater can be extracted using a water well.

Image_aquifers_0.png

roundwater
reservoirs, can be thousands of years.

Residence time for water in the Antarctic ice sheet

residence time : The amount of time a water molecule spends in one place in the water cycle, such as in a river, ocean, or atmosphere.

Image_residence-time_0.png

residence time in Antarctic ice sheet : Water in the Antarctic ice sheet has a residence time of about 17,000 years, indicating how long water remains frozen in this reservoir.

Image_residence-time-in-antarctic-ice-sheet_0.png

residence time in the ocean : Water in the ocean has a residence time of about 3,200 years, reflecting the time it takes for water to circulate through the oceanic system.

Image_residence-time-in-the-ocean_0.png

residence time in the atmosphere : Water in the atmosphere has the shortest residence time of about nine days, highlighting the rapid turnover of water vapor in the air.

Image_residence-time-in-the-atmosphere_0.png

ice sheet : A large mass of glacial ice and snow that covers a large area of land for a long period of time.

Image_ice-sheet_0.png

is about 17,000 years. That means that a molecule of water will stay as ice for about that amount of time.

The residence time for water in the ocean

residence time : The amount of time a water molecule spends in one place in the water cycle, such as in a river, ocean, or atmosphere.

Image_residence-time_0.png

residence time in the ocean : Water in the ocean has a residence time of about 3,200 years, reflecting the time it takes for water to circulate through the oceanic system.

Image_residence-time-in-the-ocean_0.png

residence time in the atmosphere : Water in the atmosphere has the shortest residence time of about nine days, highlighting the rapid turnover of water vapor in the air.

Image_residence-time-in-the-atmosphere_0.png

is much shorter—about 3,200 years.

The residence time of water in the atmosphere

residence time : The amount of time a water molecule spends in one place in the water cycle, such as in a river, ocean, or atmosphere.

Image_residence-time_0.png

residence time in the ocean : Water in the ocean has a residence time of about 3,200 years, reflecting the time it takes for water to circulate through the oceanic system.

Image_residence-time-in-the-ocean_0.png

residence time in the atmosphere : Water in the atmosphere has the shortest residence time of about nine days, highlighting the rapid turnover of water vapor in the air.

Image_residence-time-in-the-atmosphere_0.png

is the shortest of all—about nine days.

Calculating residence time

residence time : The amount of time a water molecule spends in one place in the water cycle, such as in a river, ocean, or atmosphere.

Image_residence-time_0.png

can be an important tool for developers and engineers. Engineers may consult a reservoir's residence time when evaluating how quickly a pollutant

pollutant : A chemical or other substance that harms a natural resource, often introduced into the environment by human activity.

Image_pollutant_0.png

will spread through the reservoir, for instance. Residence time ma

aquifer : An underground layer of water-bearing rock or materials like gravel, sand, or silt, from which groundwater can be extracted.

Image_aquifer_0.png

y a

aquifer : An underground layer of water-bearing rock or materials like gravel, sand, or silt, from which groundwater can be extracted.

Image_aquifer_0.png

lso influence how communities use a

aquifer : An underground layer of water-bearing rock or materials like gravel, sand, or silt, from which groundwater can be extracted.

Image_aquifer_0.png

n a

aquifer : An underground layer of water-bearing rock or materials like gravel, sand, or silt, from which groundwater can be extracted.

Image_aquifer_0.png

quifer.

Fast Fact

Breaking the Cycle
The water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

can change. Glacial retreat is the process in which glaciers melt faster than their ice can be replaced by precipitation

precipitation : All forms in which water falls to Earth from the atmosphere, including rain, snow, sleet, and hail.

Image_precipitation_0.png

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

Image_glaciers_0.png

Glacial Retreat : Glacial retreat is the process where glaciers melt faster than they are replenished by precipitation, reducing the amount of fresh water available.

Image_glacial-retreat_0.png

Fastest rate of glacial retreat : We are currently experiencing the fastest rate of glacial retreat in recorded history, impacting fresh water availability.

Image_fastest-rate-of-glacial-retreat_0.png

glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

Image_glacial-ice_0.png

. Glacial retreat limits the amount of fresh water available on Earth. We are experiencing the fastest rate of glacial retreat in recorded history.
Articles & Profiles
National Geographic: Spring Rains Darken Saturn's Moon Titan

Saturn's Moon Titan : Titan is the largest moon of Saturn, known for its thick atmosphere and surface lakes of methane.

Image_saturn-s-moon-titan_0.png

Website
USGS: Water Cycle Components
Media Credits

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Editor
Jeannie Evers

Jeannie Evers : Jeannie Evers is associated with Emdash Editing, likely as an editor or contributor.

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, Emdash Editing , Emdash Editing
Producer
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other
Last Updated

October 19, 2023

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water-cycle(WAH-tur SI-kul)
noun

movement of water between atmosphere, land, and ocean.

lake(LAYK)
noun

body of water surrounded by land.

river(RIH-vur)
noun

large stream of flowing freshwater.

glacier(GLAY-shur)
noun

mass of ice that moves slowly over land.

ice-sheet(IS SHEET)
noun

thick layer of glacial ice

glacial ice : A thick layer of ice that forms over many years from compacted snow and covers large areas of land.

Image_glacial-ice_0.png

that covers a large area of land.

aquifer(AH-kwuh-fer)
noun

an underground layer of rock or earth that holds groundwater.

vapor(VAY-pur)
noun

visible liquid suspended in the air, such as fog.

cloud (noun)(KLOWD)
noun

visible mass of tiny water droplets or ice crystals in Earth's atmosphere.

evaporation(ee-va-puh-RAY-shun)
noun

process by which liquid water becomes water vapor.

condensation(kahn-dehn-SAY-shun)
noun

process by which water vapor becomes liquid.

precipitation(pree-sih-pih-TAY-shun)
noun

all forms in which water falls to Earth from the atmosphere.

greenhouse-gas(GREEN-hows GAS)
noun

gas in the atmosphere, such as carbon dioxide, methane, water vapor

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

Image_vapor_0.png

, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere.

insulate(IHN-suh-layt)
verb

to cover with material to prevent the escape of energy (such as heat) or sound.

wind(WIHND)
noun

movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.

temperature(TEHM-peh-chur)
noun

degree

temperature : The degree of hotness or coldness measured by a thermometer with a numerical scale, indicating thermal energy.

Image_temperature_0.png

of hotness or coldness measured by a thermometer with a numerical scale.

density(DEHN-sih-tee)
noun

number of things of one kind in a given area.

cloud-condensation-nuclei-ccn

Condensation : Condensation is the process where water vapor in the atmosphere cools and changes back into liquid water, forming clouds.

Image_condensation_0.png

Cloud Condensation Nuclei (CCN) : Cloud condensation nuclei are tiny particles around which water vapor condenses to form clouds.

Image_cloud-condensation-nuclei-ccn_0.png

cloud : A visible mass of tiny water droplets or ice crystals suspended in the Earth's atmosphere.

Image_cloud_0.png

(KLOWD kahn-dehn-SAY-shun NOO-klee-i)
plural noun

microscopic bits of clay, salt, or solid pollutant around which water vapor condenses in clouds

pollutant : A chemical or other substance that harms a natural resource, often introduced into the environment by human activity.

Image_pollutant_0.png

vapor : The gaseous phase of substances that are normally liquid or solid at room temperature, such as water vapor.

Image_vapor_0.png

clouds : Visible masses of tiny water droplets or ice crystals suspended in the atmosphere.

Image_clouds_0.png

to form raindrops.

pollutant(PUH-loo-tunt)
noun

chemical or other substance that harms a natural resource.

fog(FAHG)
noun

clouds at ground level.

dew-point(DOO POYNT)
noun

temperature

temperature : The degree of hotness or coldness measured by a thermometer with a numerical scale, indicating thermal energy.

Image_temperature_0.png

at which water in the air condenses to form water droplets on objects near the ground.

air-pressure(AIR PREH-shur)
noun

force pressed on an object by air or atmosphere.

runoff(RUN-ahf)
noun

overflow of fluid from a farm or industrial factory.

snowmelt(SNOH-mehlt)
noun

water supplied by snow.

transpiration(trans-puh-RAY-shun)
noun

evaporation of water from plants.

microscopic(mi-kruh-SKAH-pihk)
adjective

very small.

pore(POR)
noun

tiny opening.

stomata(stoh-MAH-tuh)
plural noun

(singular: stoma) tiny openings on the surface of leaves that control the exchange of gases in a plant.

evapotranspiration(ee-VA-poh-tran-spur-AY-shun)
noun

loss of water from the Earth's soil by evaporation into the atmosphere and transpiration

evaporation : The process by which water changes from a liquid to a gas or vapor.

Image_evaporation_0.png

transpiration : The process by which plants release water vapor into the air through stomata in their leaves.

Image_transpiration_0.png

by plants.

ice(IS)
noun

water in its solid form.

freshwater(FREHSH-wah-tur)
adjective

having to do with a habitat or ecosystem

ecosystem : A community of living organisms in conjunction with the nonliving components of their environment, interacting as a system.

Image_ecosystem_0.png

of a lake, river, or spring.

ice-cap(IS KAP)
noun

area of fewer than 50,000 square kilometers (19,000 square miles) covered by ice

area of fewer than 50,000 square kilometers covered by ice : Refers to regions with ice coverage less than 50,000 square kilometers, indicating smaller ice fields or glaciers.

Image_area-of-fewer-than-50-000-square-kilometers-covered-by-ice_0.png

.

climate(KLI-mut)
noun

all weather

weather : The state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness, at a specific time and place.

Image_weather_0.png

conditions for a given location over a period of time.

ecosystem(EE-koh-sihs-tehm)
noun

community and interactions of living and nonliving things in an area.

weatherWEH-thur
noun

state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloud

precipitation : All forms in which water falls to Earth from the atmosphere, including rain, snow, sleet, and hail.

Image_precipitation_0.png

temperature : The degree of hotness or coldness measured by a thermometer with a numerical scale, indicating thermal energy.

Image_temperature_0.png

cloud : A visible mass of tiny water droplets or ice crystals suspended in the Earth's atmosphere.

Image_cloud_0.png

iness.

humidity(hyoo-MIH-dih-tee)
noun

amount of water vapor in the air.

fluctuate(FLUHK-shoo-ayt)
verb

to constantly change back and forth.

landscape(LAND-skayp)
noun

the geographic features of a region.

physical-geography(FIH-zih-kuhl jee-AH-gruh-fee)
noun

study of the natural features and processes of the Earth.

erosioneh-ROH-zhun
noun

act in which earth is worn away, often by water, wind

wind : The movement of air from a high-pressure zone to a low-pressure zone, caused by the uneven heating of the Earth by the sun.

Image_wind_0.png

, or ice.

valley(VAL-ee)
noun

depression in the Earth between hills.

glacial-valley(GLAY-shul VA-lee)
noun

depression

glaciers : Large masses of ice that form on land by the compaction and recrystallization of snow, which move slowly over time, shaping the landscape.

Image_glaciers_0.png

glacial depression : A depression in the Earth's surface formed by the movement of glaciers.

Image_glacial-depression_0.png

in the earth created by a moving glacier.

glacial-erratic(GLAY-shul ir-RA-tihk)
noun

rock, deposited by a glacier, that differs from the geology

geology : The study of the natural features and processes of the Earth.

Image_geology_0.png

and landscape in which it is found.

landform(LAND-form)
noun

specific natural feature on Earth's surface.

great-lakes(GRAYT LAYKS)
noun

largest freshwater bodies in the world

largest freshwater bodies in the world : The Great Lakes are the largest group of freshwater lakes by total area in the world, significant for their size and ecological importance.

Image_largest-freshwater-bodies-in-the-world_0.png

, located in the United States and Canada. Lake Huron, Lake Ontario, Lake Michigan, Lake Erie, and Lake Superior make up the Great Lakes

Great Lakes : A group of five large freshwater lakes located on the border between the United States and Canada, formed by glacial activity.

Image_great-lakes_0.png

Lake Huron : One of the five Great Lakes of North America, located between the United States and Canada.

Image_lake-huron_0.png

Lake Ontario : The easternmost of the Great Lakes, located on the border between the United States and Canada.

Image_lake-ontario_0.png

Lake Michigan : One of the five Great Lakes, entirely within the United States, known for its large size and recreational activities.

Image_lake-michigan_0.png

Lake Erie : The fourth largest of the Great Lakes by surface area, located on the border between the United States and Canada.

Image_lake-erie_0.png

Lake Superior : The largest and northernmost of the Great Lakes, known for its cold waters and large surface area.

Image_lake-superior_0.png

.

midwest(mihd-WEHST)
noun

area of the United States consisting of the following states: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin

Illinois : A state in the Midwestern region of the United States, part of the area known as the Midwest.

Image_illinois_0.png

Indiana : A state in the Midwestern United States, known for its farmland and manufacturing.

Image_indiana_0.png

Iowa : A Midwestern U.S. state known for its agriculture and rolling plains.

Image_iowa_0.png

Kansas : A U.S. state located in the Midwest, known for its flat landscape and agriculture.

Image_kansas_0.png

Michigan : A U.S. state in the Great Lakes region, known for its water resources and automotive industry.

Image_michigan_0.png

Minnesota : A U.S. state in the Upper Midwest, known for its lakes and cold winters.

Image_minnesota_0.png

Missouri : A U.S. state in the Midwest, known for its rivers and diverse geography.

Image_missouri_0.png

Nebraska : A U.S. state in the Great Plains region, known for its agriculture and prairies.

Image_nebraska_0.png

North Dakota : A U.S. state in the Upper Midwest, known for its agriculture and oil production.

Image_north-dakota_0.png

Ohio : A U.S. state in the Midwest, known for its industry and diverse landscapes.

Image_ohio_0.png

South Dakota : A U.S. state in the Midwest, known for its national parks and Native American heritage.

Image_south-dakota_0.png

Wisconsin : A U.S. state in the Midwest, known for its dairy industry and Great Lakes shoreline.

Image_wisconsin_0.png

.

current(KUHR-ehnt)
noun

steady, predictable flow of fluid within a larger body of that fluid.

residence-time(REH-sih-dehns TIM)
noun

amount of time a water molecule spends in one place in the water cycle

water cycle : The movement of water between the atmosphere, land, and ocean, involving processes like evaporation, condensation, and precipitation.

Image_water-cycle_0.png

.

groundwaterGROUND-wah-ter
noun

water found in an aquifer.

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