Water cycle

hydrological cyclehydrologic cyclewaterhydrologicalwater circulationwater cyclingcyclingevaporation caused by the sun that condensesfreshwater cyclehydro-logical cycle
The water cycle, also known as the hydrological cycle or the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth.wikipedia
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Water

H 2 Oliquid wateraqueous
The water cycle, also known as the hydrological cycle or the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth.
Water moves continually through the water cycle of evaporation, transpiration (evapotranspiration), condensation, precipitation, and runoff, usually reaching the sea.

Evaporation

evaporateevaporatedevaporates
The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow. Evaporation: The transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere. The source of energy for evaporation is primarily solar radiation. Evaporation often implicitly includes transpiration from plants, though together they are specifically referred to as evapotranspiration. Total annual evapotranspiration amounts to approximately 505000 km3 of water, 434000 km3 of which evaporates from the oceans. 86% of global evaporation occurs over the ocean.
Evaporation is an essential part of the water cycle.

Condensation

condensecondensescondensed
The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow.
The word most often refers to the water cycle.

Ice

water iceicyicing
In doing so, the water goes through different forms: liquid, solid (ice) and vapor.
It is abundant on Earth's surface – particularly in the polar regions and above the snow line – and, as a common form of precipitation and deposition, plays a key role in Earth's water cycle and climate.

Precipitation

rainfallhydrometeorannual precipitation
The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow. Precipitation: Condensed water vapor that falls to the Earth's surface. Most precipitation occurs as rain, but also includes snow, hail, fog drip, graupel, and sleet. Approximately 505000 km3 of water falls as precipitation each year, 398000 km3 of it over the oceans. The rain on land contains 107000 km3 of water per year and a snowing only 1000 km3. 78% of global precipitation occurs over the ocean.
Precipitation is a major component of the water cycle, and is responsible for depositing the fresh water on the planet.

Climate change

climatic changeclimatechanging climate
The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables.
Life affects climate through its role in the carbon and water cycles and through such mechanisms as albedo, evapotranspiration, cloud formation, and weathering.

Rain

rainfallrainstormtorrential rain
Precipitation: Condensed water vapor that falls to the Earth's surface. Most precipitation occurs as rain, but also includes snow, hail, fog drip, graupel, and sleet. Approximately 505000 km3 of water falls as precipitation each year, 398000 km3 of it over the oceans. The rain on land contains 107000 km3 of water per year and a snowing only 1000 km3. 78% of global precipitation occurs over the ocean.
Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth.

Evapotranspiration

potential evapotranspirationevaporationevapotranspired
Evapotranspiration is water transpired from plants and evaporated from the soil. Evaporation: The transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere. The source of energy for evaporation is primarily solar radiation. Evaporation often implicitly includes transpiration from plants, though together they are specifically referred to as evapotranspiration. Total annual evapotranspiration amounts to approximately 505000 km3 of water, 434000 km3 of which evaporates from the oceans. 86% of global evaporation occurs over the ocean.
Evapotranspiration is an important part of the water cycle.

Snowmelt

snow meltmeltwatermelt snow
Snowmelt: The runoff produced by melting snow.
Water produced by snowmelt is an important part of the annual water cycle in many parts of the world, in some cases contributing high fractions of the annual runoff in a watershed.

Surface runoff

runoffagricultural runoffrun-off
The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow. Runoff: The variety of ways by which water moves across the land. This includes both surface runoff and channel runoff. As it flows, the water may seep into the ground, evaporate into the air, become stored in lakes or reservoirs, or be extracted for agricultural or other human uses.
This might occur because soil is saturated to full capacity, because rain arrives more quickly than soil can absorb it, or because impervious areas (roofs and pavement) send their runoff to surrounding soil that cannot absorb all of it. Surface runoff is a major component of the water cycle.

Earth

terrestrialworldGlobal
The water cycle, also known as the hydrological cycle or the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth.
This water cycle is a vital mechanism for supporting life on land and is a primary factor in the erosion of surface features over geological periods.

Subsurface flow

subsurfacesub-surface flowssubsurface runoff
Subsurface flow: The flow of water underground, in the vadose zone and aquifers. Subsurface water may return to the surface (e.g. as a spring or by being pumped) or eventually seep into the oceans. Water returns to the land surface at lower elevation than where it infiltrated, under the force of gravity or gravity induced pressures. Groundwater tends to move slowly and is replenished slowly, so it can remain in aquifers for thousands of years.
Subsurface flow, in hydrology, is the flow of water beneath earth's surface as part of the water cycle.

Streamflow

stream flowflowriver flow
Runoff: The variety of ways by which water moves across the land. This includes both surface runoff and channel runoff. As it flows, the water may seep into the ground, evaporate into the air, become stored in lakes or reservoirs, or be extracted for agricultural or other human uses.
Streamflow, or channel runoff, is the flow of water in streams, rivers, and other channels, and is a major element of the water cycle.

Water vapor

water vapourvaporevaporation
In doing so, the water goes through different forms: liquid, solid (ice) and vapor.
Dew point temperature and relative humidity act as guidelines for the process of water vapor in the water cycle.

Groundwater

ground waterunderground waterground
Runoff and water emerging from the ground (groundwater) may be stored as freshwater in lakes.
Groundwater can be a long-term 'reservoir' of the natural water cycle (with residence times from days to millennia), as opposed to short-term water reservoirs like the atmosphere and fresh surface water (which have residence times from minutes to years).

Snow

snowfallsnow covernival
Precipitation: Condensed water vapor that falls to the Earth's surface. Most precipitation occurs as rain, but also includes snow, hail, fog drip, graupel, and sleet. Approximately 505000 km3 of water falls as precipitation each year, 398000 km3 of it over the oceans. The rain on land contains 107000 km3 of water per year and a snowing only 1000 km3. 78% of global precipitation occurs over the ocean.
Snow science often leads to predictive models that include snow deposition, snow melt, and snow hydrology—elements of the Earth's water cycle—which help describe global climate change.

Fresh water

freshwaterfreshlimnic
The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables.
Water cycle

Deforestation

deforestedland clearingforest clearing
deforestation and afforestation
The water cycle is also affected by deforestation.

Advection

advectiveadvectedadvection equation
Advection: The movement of water through the atmosphere. Without advection, water that evaporated over the oceans could not precipitate over land.
Advection is important for the formation of orographic clouds and the precipitation of water from clouds, as part of the hydrological cycle.

Plant

plantsfloraplant kingdom
Evaporation: The transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere. The source of energy for evaporation is primarily solar radiation. Evaporation often implicitly includes transpiration from plants, though together they are specifically referred to as evapotranspiration. Total annual evapotranspiration amounts to approximately 505000 km3 of water, 434000 km3 of which evaporates from the oceans. 86% of global evaporation occurs over the ocean.
Land plants are key components of the water cycle and several other biogeochemical cycles.

Hydrosphere

waterhydrosphericatmospheric cycling
The water cycle describes the processes that drive the movement of water throughout the hydrosphere.
The water cycle refers to the transfer of water from one state or reservoir to another.

SAC-D

Aquarius
An instrument carried by the SAC-D satellite Aquarius, launched in June, 2011, measured global sea surface salinity.
By measuring ocean salinity, scientists are better able to understand the Earth's water cycle and ocean circulation.

Carbon cycle

carboncarbon cyclingglobal carbon cycle
Runoff also plays a part in the carbon cycle, again through the transport of eroded rock and soil.
Along with the nitrogen cycle and the water cycle, the carbon cycle comprises a sequence of events that are key to make Earth capable of sustaining life.

Residence time

turnover timemean residence timeflushing time
The residence time of a reservoir within the hydrologic cycle is the average time a water molecule will spend in that reservoir (see adjacent table). It is a measure of the average age of the water in that reservoir.
More specifically it is the time during which water remains within an aquifer, lake, river, or other water body before continuing around the hydrological cycle.

Biogeochemical cycle

biogeochemical cyclesbiogeochemical cyclingbiogeochemical
While the water cycle is itself a biogeochemical cycle, flow of water over and beneath the Earth is a key component of the cycling of other biogeochemicals.
There are biogeochemical cycles for the chemical elements calcium, carbon, hydrogen, mercury, nitrogen, oxygen, phosphorus, selenium, and sulfur; molecular cycles for water and silica; macroscopic cycles such as the rock cycle; as well as human-induced cycles for synthetic compounds such as polychlorinated biphenyl (PCB).