Talk:Water cycle

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Former good article Water cycle was one of the Natural sciences good articles, but it has been removed from the list. There are suggestions below for improving the article to meet the good article criteria. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.
Article milestones
Date Process Result
December 3, 2006 Good article nominee Listed
May 22, 2007 Peer review Reviewed
May 4, 2008 Good article reassessment Delisted
Current status: Delisted good article
edit·history·watch·refresh Stock post message.svg To-do list for Water cycle:

--> expand section on climate regulation, or remove --> expand section on changes over time --> expand section on biogeochemical cycling, or remove --> insure all references are in place --> improve da writing The water cycle — technically known as the hydrologic cycle or hydrological cycle — is the continuous circulation of water within the Earth's hydrosphere, and is driven by solar radiation and cloud condensation nuclei


The text removed as follows is not accurate: dominiuqe "Precipitation seldom falls in the oceans, because under normal circumstances, mountain ranges are needed to induce condensation and the formation of clouds."

I was thinking about fixing it...but removal may be the best fix. Hard Raspy Sci 02:53, 7 Feb 2005 (UTC)


You can know about the new hydrological cycle discovered recently at the following address:

Simplified Cycle[edit]

Most people looking up "Water cycle" are not looking for the amount of information available on this page. I am not suggesting, of course, that detailed information should be removed, as that would defeat the purpose of Wikipedia. However, why not create a section that is a simplified version of the water cycle; something that would be useful for an elementary or middle school teacher, not a scientist.


What happened to the image from USGS (Water_cycle.png)? --WCFrancis 13:58, 13 May 2005 (UTC)

Hey, I just found this. I am with USGS and I built our Water Cycle site ( We did just "adjust" the diagram in order to add "sublimation", changed "transpiration" to "evapotranspiration", and added a needed "evaporation" arrow from surface water (the lake), to show that evaporation also occurs on land.

I'm afraid there never was a PNG version, but we are trying to create a library of various sized JPGs and PDFs that users will be able to download (sadly, this depends on funding).

Email me ( if you have a specific need.

Also, note the diagram is available in almost 60 language and we are now getting in translation of summary text.

Significant Figures[edit]

Any useful reason for reporting calculation results to 14 significant figures? -- WCFrancis 18:31, 16 Jun 2005 (UTC)

I wrote down whatever the calculator showed, leaving it up to the reader to round results as required. QUITTNER 18:51, 16 Jun 2005 (UTC)

How much water ...?[edit]

Remove the following section from the article for discussion:

==How much water==

Clouds can hold only a limited amount of water:[1]

At 32°F = 0°C the specific volume is 3305.7 cu ft/lb
At 120°F = 49°C the specific volume is 203.47 cu ft/lb

Converting the reciprocal to metric, 1 lb/cu ft = 1.60x104 g/m3.

If a cloud hits a cold front, then it sheds water/hail/snow until the amount of water it holds is not above the saturation point at that particular lower temperature.

Curve fitting can help. To find out how much moisture a cloud can hold use x=°C at the cloud, and y=the maximum moisture (="at saturation") the cloud can hold in gram per cubic meter (g/m3) at that temperature, where E-6 means "times 10 to the power of minus 6", use:

An Example:
Assuming that it is known that at the cloud the temperature is 32°C, and it has just started to rain, it would be reasonable to conclude that the moisture contained by the cloud would be at the saturation level, which, at 32°C, is 33.8 g/m3. Later, when the temperature at the cloud has been reduced to 20°C, the maximum moisture the cloud can hold is only 17.3 g/m3. Therefore the amount of water that came down as rain so far is about 33.8-17.3=16.5 g/m3.

Similarly, to find out y=the minimum temperature in °C at the cloud at which the given x=amount of moisture in g/m3 can be retained by the cloud use

  1. ^ "Steam Tables. Properties of Saturated and Superheated Steam" (1940), The Superheater Company Limited.

It seems there is a bit of confusion here. Is the section referring to water or water vapor? The saturation comments imply water vapor, but the content implies liquid water. And clouds are liquid water or ice crystals. Something amiss here. Also I don't think we need the curve fitting equations. And the outdated reference with its cu ft/lb ... surely we don't need that and can do better. Vsmith 00:29, 8 August 2005 (UTC)

Compartment or reservoir[edit]

I have a technical bias, if it's not obvious, so I should ask what term would be best: compartment or reservoir? Either way, the idea should be illustrated. Reservoir already connotes water storage, but behind a dam, and I prefer the term. What thoughts? Cheers, Daniel Collins 16:34, 27 March 2006 (UTC).

Removed example: residence time[edit]

I removed the following text (which was initially added by me anyhow). I should concede it's a bit too textbookish. Daniel Collins 18:21, 7 September 2006 (UTC)

Example: Calculating the residence time of the oceans
As an example of how the residence time is calculated, consider the oceans. The volume of the oceans is roughly 1,370×106 km³. Precipitation over the oceans is about 0.398×106 km³/year and the flow of water to the oceans from rivers and groundwater is about 0.036×106 km³/year. By dividing the total volume of the oceans by the rate of water added (in units of volume over time) we obtain the residence time of 3,200 years—the average time it takes a water molecule that reaches an ocean to evaporate.

What's so special about marsupials?[edit]

The text indicates that water in the atmosphere also comes through persiration from mammals and marsupials. Wikipedia specifies that marsupials are also mammals. What is so special about marsupials to make them worth mentioning separately? Could we not confine the text to mammals?

I would have done it myself if I was sure that the author of the text did not have something special in mind.

Afil 01:06, 19 September 2006 (UTC)

By all means, do make such changes yourself. Daniel Collins 15:09, 19 September 2006 (UTC)

Conservation of mass: Appropriate for this article?[edit]

I originally added it, but now I'm not so sure, so I'm moving it here. Daniel Collins 18:57, 24 October 2006 (UTC)

Average annual water transport[1]
Water flux Average rate
(10³ km³/year)
Precipitation over land 107
Evaporation from land 71
Runoff & groundwater from land 36
Precipitation over oceans 398
Evaporation from oceans 434
The total amount, or mass, of water in the water cycle remains essentially constant, as does the amount of water in each reservoir of the water cycle. This means that rate of water added to one reservoir must equal, on average over time, the rate of water leaving the same reservoir.
The adjacent table contains the amount of water that falls as precipitation or rises as evaporation, for both the land and oceans. The runoff and groundwater discharge from the land to the oceans is also included. From the law of the conservation of mass, whatever water moves into a reservoir, on average, the same volume must leave. For example, 107 thousand cubic km (107 × 10³ km³) of water falls on land each year as precipitation. This is equal to the sum of the evaporation (71 × 10³ km³/year) and runoff (36 × 10³ km³/year) of water from the land.
Water that cycles between the land and the atmosphere in a fixed area is referred to as moisture recycling.

I was wondering that myself. People pollute portions of the water supply to such a degree that a small percentage may not get back into the cycle, like in Superfund sites where there have been chemical spills and nuclear contanimation. Thegreatdr 19:08, 24 October 2006 (UTC)
Sure, it's not completely accurate at the local scale. It's just a very useful concept. Violations of the principle are usually of more interest. Daniel Collins 19:27, 24 October 2006 (UTC)
Seems fair enough for the article. There are some other terms - like groundswater storage, and aquifer mining - which might affect the small scale balance William M. Connolley 20:17, 24 October 2006 (UTC)


I felt that the article satisfied all the criteria. I'm a non-specialist and I found it interesting and thorough. Congratulations. Readro 22:26, 6 December 2006 (UTC)

Time for reassessment. I don't think this article fit the criteria from late 2006, let alone today. The lead has become inadequate for the article, and there are too few inline references. Thegreatdr (talk) 20:17, 2 May 2008 (UTC)


Who discovered the Hydrologic Water Cycle, or at least figured out the process, and when? I think that should be noted.


"Water Travels in a Cycle ,yes it does. Water travels in a cycle, yes it does. It goes up as evaporation, forms clouds as condensation, and falls down as precipitation ,yes it does"

I was wondering about the energetics of the water cycle. Water absorbs latent heat as it turns to vapor. At this point an interesting thin happens, as water vapor mixes with dry air, the resulting moist air is lighter than dry air.

The moist light air begins to rise upwards under the action of gravity, (lighter moist air rising as denser dry air comes down to replace it). At a certain altitude the vapor condenses back to water and comes down as rain. However as the moist air has not preformed any 'work' the heat that the vapor gives out at the higher altitude must be exactly equal to the heat that was absorbed as the water turned to vapor at sea level.

The above may be confirmed by looking upo the Newmans Encyclopedia of Science.

Looking at the Rain cycle as a heat engine we would notice that this is one 'Heat Engine' that absorbs a quantity of heat say 'H' from a 'source' and gives back exactly the same quantity of heat 'H' to the 'sink'.

By the application of heat and work laws the Rain cycle must produce zero work (H - H = 0)yet a large mass of water has obtained a considerable amount of potential energy.

I would be able to give more details in a few days.

Adess Singh 17:47, 28 February 2007 (UTC)Adess Singh

Mr Singh: Work is done as the water evaporates. The water vapour performs work against the atmosphere. Potential gravitational energy is lost when the warm moist air rises. — Preceding unsigned comment added by (talkcontribs) 03:49, 9 May 2016 (UTC)

I'm majoring in Geography and I am fairly new.[edit]

I have a question regarding the following in this article. "Over the past century the water cycle has become more intense, with the rates of evaporation and precipitation both increasing. This is an expected outcome of global warming, as higher temperatures increase the rate of evaporation due to warmer air's higher capacity for holding moisture."

Would having a more intense water cycle result in having more fresh water rain in the ocean? From what I know having too much fresh water in the ocean is bad because it disrupts the Gulf Stream due to the fact that fresh water is less dense than salt water. —The preceding unsigned comment was added by Axinthevoid (talkcontribs) 04:33, 11 April 2007 (UTC).

Can someone fix "atoms of water"[edit]

I'm sorry the page is protected. I wanted to correct the reference to "atoms of water", which should be "molecules of water". Maybe someone with the necessary power or knowledge can take care of that. TIA. --Sfulle 13:02, 22 May 2007 (UTC)

Lead is a copy-and-paste job.[edit]

The lead is identical to this. It could be in reverse order, but I assume that an editor has just copy-and-pasted it. Looking at this article altogether, it's seems hardly deserving of GA. Ashnard Talk Contribs 15:49, 6 December 2007 (UTC)

It needs more inline references as well. Nowadays, this wouldn't pass as GA. Thegreatdr (talk) 06:49, 24 January 2008 (UTC)
Unverifiable content relating to evapotranspiration and to atmospheric circulation has been removed. The inline reference concern appears to be satisfied. --Paleorthid (talk) 16:30, 24 January 2008 (UTC)
Not particularly. Normally, GA articles have an inline reference frequency of at least one per paragraph. There are whole "un-inline referenced" sections to this article. I've put it up for reassessment, just in case my GA senses are off here. Thegreatdr (talk) 20:18, 2 May 2008 (UTC)

water cycle[edit]

The water cycle is have 5 process: 1. evaporation 2. condensation 3. precipitation 4. infiltration 5. percolation —Preceding unsigned comment added by (talk) 11:33, 11 February 2008 (UTC)

it evaporates so it gets clean and goes to companies to double check if its clean then it goes to different countries —Preceding unsigned comment added by (talk) 20:25, 15 January 2009 (UTC)

I am not experienced enough but there's an unnoticed bit of vandalism that needs reverting. a huge chunk of text has been removed about 6 edits ago. can an experienced editor please get it back. thanks. this is the page where the text was deleted. Hornsofthebull (talk) 17:49, 28 January 2009 (UTC)

Done. Mikenorton (talk) 17:53, 28 January 2009 (UTC)

History of discovery[edit]

Could we have a section regarding the history of thought regarding the water cycle? Faro0485 (talk) 22:59, 6 July 2009 (UTC) As far as history section goes it isn't very detailed. It talks of early attempts to explain which are not very accurate. Earliest description of complete water cycle is found in Mahabharata.

Interesting Biblical Reference[edit]

Wording varies from one translation to another, this translation is from NCV. The Book of Job was written between the second millennium B.C.(2000-1000), likely closer to the end, because in Job 19:14 make reference to iron which was not available till the 12th Century B.C. (1200 to 1101 B.C.).

27 "He evaporates the drops of water from the earth and turns them into rain. 28 The rain then pours down from the clouds, and showers fall on people. 29 No one understands how God spreads out the clouds or how he sends thunder from where he lives. Job 36:27-29

"Scripture taken from the New Century Version. Copyright © 2005 by Thomas Nelson,

  Inc. Used by permission. All rights reserved." 

--wolf wood j 17:14 24 November 2009 (PST)

Individual water molecules can come and go[edit]

The lead ends with the phrase "individual water molecules can come and go". I find this to be rather badly worded, and not absolutely sure what it means, though I guess it is referring to dissociation and reverse processes. Could an expert clarify this please. Derek Andrews (talk) 23:31, 10 September 2009 (UTC)

Contradictory wording?[edit]

In paragraph one, it says "Since the water cycle is truly a cycle, there is no beginning or end."

Paragraph two finishes with: "Over time, the water returns to the ocean, where our water cycle started."

If it has no beginning, saying it "started" is contradictory. IMO Wanderer57 (talk) 18:10, 14 September 2009 (UTC)

the water cycle starts with a droplet from the ocean and goes in to the sky and forms a cloud then it rains and then the droplet comes down as a rain drop and from the raindrop it starts all over again after it evaporates and goes back to the sea. —Preceding unsigned comment added by (talk) 15:42, 25 October 2009 (UTC)

What happens: it rains (condensation) and it rains water, of course (precipitation). The water goes into the runoff and becomes ground water in which eventually goes to the ocean. Then the water evaporates and the cycle repeats over and over and over again. — Preceding unsigned comment added by (talk) 20:51, 19 March 2012 (UTC)

Add stratosphere and global warming connection reference[edit]

  • Anderson, J. G.; Wilmouth, D. M.; Smith, J. B.; Sayres, D. S. (2012). "UV Dosage Levels in Summer: Increased Risk of Ozone Loss from Convectively Injected Water Vapor". Science. 337 (6096): 835. doi:10.1126/science.1222978. (talk) 03:58, 30 July 2012 (UTC)

History of hydrologic cycle theory[edit]

I came to this page looking for the answer to the question: who discovered the water cycle? I have found this question on several question/answer sites on the web, which tells me that it is a relevant question to answer. I added something, but note that it is based on mostly just one source. -- leuce (talk) 18:39, 14 July 2013 (UTC)

Interestingly enough, most initial sources are in the Bible. Ecclesiastes is mentioned in the text, and Job is mentioned in the Talk page. I found it in Isiah 55: "As the rain and snow come down from heaven, and do not return to it without watering the earth and making it bud and flourish ...."

[2] T3mplar (talk) 12:54, 1 June 2016 (UTC)


Description: "Runoff and and water emerging from the ground" - Can someone with access remove the extra and? — Preceding unsigned comment added by (talk) 14:01, 18 October 2013 (UTC)

 Done, thanks. — Reatlas (talk) 11:38, 19 October 2013 (UTC)

Image: Hydrological Cycle E vs P.jpg[edit]

I found the "Hydrological Cycle E vs P" graph rather confusing. It claims to show precipitation and evaporation as a function of latitude using an idealised model, but the y-axis shows a unit of solar insolation (W/m^2). The assumptions of the model are explained in jargon and acronyms. I think this is a useful and interesting graph that shows the fundamental science behind the trends shown in another image on this page (the global map which shows evaporation minus precipitation) but it is not at all clear. Could someone with a better understanding of the subject than me please write a clearer explanation of the graph? — Preceding unsigned comment added by (talk) 03:40, 9 May 2016 (UTC)

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  1. ^ Dr. Art's Guide to Planet Earth. The Water Cycle. Retrieved on 2006-10-24.
  2. ^ Scripture quotations taken from The Holy Bible, New International Version NIV Copyright 1973, 1978, 1984, 2011 by Biblica, Inc. Used by permission. All rights reserved worldwide.