Water Cycle -Prince Kumar

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The Mini Book Of

By

Prince Kumar.


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The Book Contains Of1. The Meaning of Water Cycle.2. Water..3. The Resources of Water...4. The Uses of Water5. Evaporation6. Transpiration..7. Condensation..8. Precipitation...9. Infiltration.....10. Run Off...

ll the Best


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1. The Meaning of Water Cycle.

The water cycle, also known as the hydrologic cycle or the H2O cycle,

describes the continuous movement of water on, above and below the surface

of the Earth. The mass water on Earth remains fairly constant overtime 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. The water moves from one reservoir toanother, such as from river to ocean, or from the ocean to the atmosphere,

by the physical processes of evaporation, condensation, precipitation,

infiltration, runoff, and subsurface flow. In so doing, the water goes

through different phases: liquid, solid (ice), and gas (vapor).

The water cycle involves the exchange of energy, which leads totemperature changes. For instance, when water evaporates, it takes up

energy from its surroundings and cools the environment. When itcondenses, it releases energy and warms the environment. These heat

exchanges influence climate. The evaporative phase of the cycle purifieswater which then replenishes the land with freshwater. The flow of liquid

water and ice transports minerals across the globe. It is also involved inreshaping the geological features of the Earth, through processes including


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erosion and sedimentation. The water cycle is also essential for the

maintenance of most life and ecosystems on the planet.


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2. Water.

Water is a chemical compound with the chemical formula H2O.

A water molecule contains one oxygen and two hydrogen atoms

connected by covalent bonds. Water is a liquid at standard ambient

temperature and pressure, but it often co-exists on Earth with its solid

state, ice, and gaseous state, steam (water vapor). Water also exists in a

liquid crystal state near hydrophilic surfaces.Water covers 71% of the Earth's surface, and is vital for all known

forms of life. On Earth, 96.5% of the planet's water is found in seas

and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of

Antarctica and Greenland, a small fraction in other large waterbodies, and 0.001% in the air as vapor, clouds (formed of solid and

liquid water particles suspended in air), and precipitation. Only 2.5%of the Earth's water is fresh water, and 98.8% of that water is in ice

and groundwater. Less than 0.3% of all freshwater is in rivers, lakes,

and the atmosphere, and an even smaller amount of the Earth'sfreshwater (0.003%) is contained within biological bodies and

manufactured products.


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Water on Earth moves continually through the water cycle of

evaporation and transpiration, condensation, precipitation, and runoff,

usually reaching the sea. Evaporation and transpiration contribute to theprecipitation over land.

Safe drinking water is essential to humans and other life forms even

though it provides no calories or organic nutrients. Access to safe

drinking water has improved over the last decades in almost every part ofthe world, but approximately one billion people still lack access to safe water

and over 2.5 billion lack accesses to adequate sanitation. There is a clear

correlation between access to safe water and GDP per capita.However, some observers have estimated that by 2025 more than half of

the world population will be facing water-based vulnerability. A report,issued in November 2009, suggests that by 2030, in some developingregions of the world, water demand will exceed supply by 50%. Water

plays an important role in the world economy, as it functions as a solvent

for a wide variety of chemical substances and facilitates industrial cooling

and transportation. Approximately 70% of the fresh water used byhumans goes to agriculture.


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ater


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3. The Resources of Water.

Water resources are sources of water that are useful or potentially useful.

Uses of water include agricultural, industrial, household, recreational

and environmental activities. The majority of human uses require freshwater.

97 percent of the water on the Earth is salt water and only three percent

is fresh water; slightly over two thirds of this is frozen in glaciers and polarice caps. The remaining unfrozen fresh water is found mainly as

groundwater, with only a small fraction present above ground or in the

air.

Fresh water is a renewable resource, yet the world's supply ofgroundwater is steadily decreasing, with depletion occurring most

prominently in Asia and North America, although it is still unclearhow much natural renewal balances this usage, and whether ecosystems

are threatened. The framework for allocating water resources to water

users (where such a framework exists) is known as water rights.


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The

Resources of

Water

GlaciersPonds

Dams

Oceans Rivers


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4. The Uses of Water.

Water use can mean the amount of water used by a household or a

country, or the amount used for a given task or for the production of a

given quantity of some product or crop. The term "water footprint" isoften used to refer to the amount of water used by an individual,

community, business, or nation.

World water use has been growing rapidly in the last hundred years.From 1900 to 2000, water use for agriculture went from about 500

to 2,500 cubic kilometers per year, while total use rose from around

600 to more than 3,000 cubic kilometers per year. Agriculture uses

70% of water resources.

In the U.S, the typical single family home uses about 69.3 gallons

(262 liters) of water per day (2008 estimate). This includes (indecreasing order) toilet use, washing machine use, showers, baths, faucet

use, and leaks.


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Irrigation Industries

Other Uses


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5. Evaporation.

Evaporation is a type of vaporization of a liquid that occurs from the

surface of a liquid into a gaseous phase that is not saturated with the

evaporating substance. The other type of vaporization is boiling, which ischaracterized by bubbles of saturated vapor forming in the liquid phase.

Steam produced in a boiler is another example of evaporation occurring

in a saturated vapor phase. Evaporation that occurs directly from thesolid phase below the melting point, as commonly observed with ice at or

below freezing or moth crystals (naphthalene or paradichlorobenzine), is

called sublimation.

On average, a fraction of the molecules in a glass of water have enough

heat energy to escape from the liquid. Water molecules from the air enterthe water in the glass, but as long as the relative humidity of the air in

contact is less than 100% (saturation), the net transfer of watermolecules will be to the air. The water in the glass will be cooled by the

evaporation until equilibrium is reached where the air supplies the amountof heat removed by the evaporating water. In an enclosed environment

the water would evaporate until the air is saturated.


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With sufficient temperature, the liquid would turn into vapor quickly (see

boiling point). When the molecules collide, they transfer energy to each

other in varying degrees, based on how they collide. Sometimes thetransfer is so one-sided for a molecule near the surface that it ends up with

enough energy to 'escape'.

Evaporation is an essential part of the water cycle. The sun (solar

energy) drives evaporation of water from oceans, lakes, moisture in thesoil, and other sources of water. In hydrology, evaporation and

transpiration (which involves evaporation within plant stomata) are

collectively termed evapotranspiration. Evaporation of water occurs whenthe surface of the liquid is exposed, allowing molecules to escape and form

water vapor; this vapor can then rise up and form clouds.


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6. Transpiration.

The Vaporization of water from Trees, plants .Water vapor is a gas

that cannot be seen. In this process water is even evaporated from lands.


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7. Condensation.

Condensation is the change of the physical state of matter from gas phase

into liquid phase, and is the reverse of vaporization. It can also be defined

as the change in the state of water vapor to water/any liquid when incontact with any surface. When the transition happens from the gaseous

phase into the solid phase directly, the change is called deposition.

Condensation is initiated by the formation of atomic/molecular clustersof that species within its gaseous volumelike rain drop or snow-flake

formation within cloudsor at the contact between such gaseous phase and

a liquid or solid surface. Condensation commonly occurs when a vapor is

cooled and/or compressed to its saturation limit when the molecular

density in the gas phase reaches its maximal threshold. Vapor coolingand compressing equipment that collects condensed liquids is called a"condenser. Condensation is a crucial component of distillation, an

important laboratory and industrial chemistry application.

Because condensation is a naturally occurring phenomenon, it can oftenbe used to generate water in large quantities for human use. Many

structures are made solely for the purpose of collecting water fromcondensation, such as air wells and fog fences. Such systems can often be


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used to retain soil moisture in areas where active desertification is

occurringso much so that some organizations educate people living in

affected areas about water condensers to help them deal effectively with thesituation.

It is also a crucial process in forming particle tracks in a cloud chamber.

In this case, ions produced by an incident particle act as nucleation

centers for the condensation of the vapor producing the visible "cloud"trails.


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8. Precipitation.

In meteorology, precipitation (also known as one of the classes of

hydrometeors, which are atmospheric water phenomena) is any product of

the condensation of atmospheric water vapor that falls under gravity. Themain forms of precipitation include drizzle, rain, sleet, snow, grapple and

hail. Precipitation occurs when a local portion of the atmosphere becomes

saturated with water vapor, so that the water condenses and"precipitates". Thus, fog and mist are not precipitation but suspensions,

because the water vapor does not condense sufficiently to precipitate. Two

processes, possibly acting together, can lead to air becoming saturated:

cooling the air or adding water vapor to the air. Generally, precipitation

will fall to the surface; an exception is virago which evaporates beforereaching the surface. Precipitation forms as smaller droplets coalesce viacollision with other rain drops or ice crystals within a cloud. Rain drops

range in size from oblate, pancake-like shapes for larger drops, to small

spheres for smaller drops. Unlike raindrops, snowflakes grow in a variety

of different shapes and patterns, determined by the temperature andhumidity characteristics of the air the snowflake moves through on its way to

the ground. While snow and ice pellets require temperatures close to the


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ground to be near or below freezing, hail can occur during much warmer

temperature regimes due to the process of its formation.

Moisture overriding associated with weather fronts is an overall majormethod of precipitation production. If enough moisture and upward

motion is present, precipitation falls from convective clouds such as

cumulonimbus and can organize into narrow rain bands. Where

relatively warm water bodies are present, for example due to waterevaporation from lakes, lake-effect snowfall becomes a concern downwind

of the warm lakes within the cold cyclonic flow around the backside of extra

tropical cyclones. Lake-effect snowfall can be locally heavy. Thundersnow is possible within a cyclone's comma head and within lake effect

precipitation bands. In mountainous areas, heavy precipitation is possiblewhere upslope flow is maximized within windward sides of the terrain atelevation. On the leeward side of mountains, desert climates can exist due

to the dry air caused by compression heating. The movement of the

monsoon trough, or intertropical convergence zone, brings rainy seasons

to savannah climes.

Precipitation is a major component of the water cycle, and is responsible

for depositing the fresh water on the planet. Approximately 505,000


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cubic kilometers (121,000 cu mi) of waterfalls as precipitation each

year; 398,000 cubic kilometers (95,000 cu mi) of it over the oceans

and 107,000 cubic kilometers (26,000 cu mi) over land. Giventhe Earth's surface area, that means the globally averaged annual

precipitation is 990 millimeters (39 in), but over land it is only 715

millimeters (28.1 in). Climate classification systems such as theKoppel climate classification system use average annual rainfall to help

differentiate between differing climate regimes.

The urban heat island effect may lead to increased rainfall, both in

amounts and intensity, downwind of cities. Global warming is alsocausing changes in the precipitation pattern globally.

Precipitation may occur on other celestial bodies, e.g. when it gets cold,Mars has precipitation which most likely takes the form of ice needles,

rather than rain or snow.


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9. Infiltration.

The flow of water from the ground surface into the ground is known as

Infiltration. Once infiltrated, the water becomes soil moisture or

groundwater.


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10. Run off.

There is 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 is keeping the process always interchanging. Again the same process

will be held. In this process all of water that is why this Cycle is known as

The Water Cycle.

By,

Prince Kumar.

The Mini Book of Water Cycle.

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Water Cycle -Prince Kumar