Water vapour - Revision history

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	[[Category:Done ~~2015~~-09-06]]		[[Category:Done 2017-07-01]]
	[[File:kettle-653673_640.jpg\|360px\|thumb\|right\|Figure 1. Although invisible, water vapour is one component of the steam released by a boiling kettle.<ref>Pixabay. (September 3, 2015). ''Kettle Steam'' [Online]. Available: https://pixabay.com/p-653673/?no_redirect</ref>]]		[[File:kettle-653673_640.jpg\|360px\|thumb\|right\|Figure 1. Although invisible, water vapour is one component of the [[wet steam]] released by a boiling kettle, the visible portion is microscopic droplets of water suspended in the air.<ref>Pixabay. (September 3, 2015). ''Kettle Steam'' [Online]. Available: https://pixabay.com/p-653673/?no_redirect</ref>]]

	<onlyinclude>'''Water vapour''' is ~~simply~~ [[water]] ~~that is present~~ in ~~its~~ [[gas]]eous ~~form~~ instead of [[liquid]] form. It can be formed either through a process of [[evaporation]] or [[sublimation]]. Unlike [[cloud]]s, fog, or mist which are simply suspended particles of liquid water in the [[air]], water vapour itself cannot be seen because it is in gaseous form.</onlyinclude><ref name=climap/>		<onlyinclude>'''Water vapour''' is [[water]] in [[gas]]eous instead of [[liquid]] form.
			It can be formed either through a process of [[evaporation]] or [[sublimation]]. Unlike [[cloud]]s, fog, or mist which are simply suspended particles of liquid water in the [[air]], water vapour itself cannot be seen because it is in gaseous form.</onlyinclude><ref name=climap/>

	It is ~~important to distinguish~~ water ~~vapour from~~ [[steam]], ~~as the two tend to be confused with each other as the difference between the two~~ is ~~not always clear~~. ~~Both steam~~ and water vapour are ~~water in gaseous forms~~, ~~but the~~ [[~~temperature~~]] ~~difference between~~ the ~~two is what sets them apart. Water vapour is gaseous~~ water ~~that is below its~~ [[~~boiling point~~]]~~, meaning that vapour can be condensed by increasing~~ [[~~pressure~~]] ~~without actually changing the temperature~~. ~~Essentially~~, ~~water vapour is~~ ''~~cooler~~'' ~~than steam~~, ~~which is~~ water vapour in ~~gaseous~~ form ~~above its boiling point~~.		Water vapour in the [[atmosphere]] is often below its [[boiling point]]. When water is boiled the water evaporates much faster and makes [[steam]]. Steam often has droplets of water, which is what is seen water is boiling. Since both water droplets and water vapour are present, this is called [[wet steam]] (also called [[wet vapour]]). As the mixture gets hotter, the water droplets go away and it becomes [[dry steam]] (also called [[dry vapour]]).<ref name=Bhatt> Bhattacharjee, ''Thermodynamics: an interactive Approach''. Pearson, 2015.</ref> [[Power plant]]s use water vapour in the form of steam (dry is better, but wet is used too) as a [[working fluid]] to turn their [[turbine]]s to make [[electricity]].

	==Atmospheric Water Vapour==		==Atmospheric Water Vapour==
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	Water vapour is actually the most abundant [[greenhouse gas]] in the atmosphere, and the most potent of all the greenhouse gases as a result of its [[chemical]] structure. Its presence accounts for around two thirds of the natural [[greenhouse effect]].<ref name=climap>Climap. (September 3, 2015). ''Water Vapour'' [Online]. Available: http://climap.net/water-vapor</ref> In the past there has been debate over how severe an impact water vapour has on [[global warming]], but recently studies have confirmed that the amplification that water vapour has on heat is strong enough to double climate warming caused by increased CO<sub>2</sub> levels.<ref>Kathryn Hansen, NASA. (September 3, 2015). ''Water Vapor Confirmed as Major Player in Climate Change'' [Online]. Available: http://www.nasa.gov/topics/earth/features/vapor_warming.html</ref>		Water vapour is actually the most abundant [[greenhouse gas]] in the atmosphere, and the most potent of all the greenhouse gases as a result of its [[chemical]] structure. Its presence accounts for around two thirds of the natural [[greenhouse effect]].<ref name=climap>Climap. (September 3, 2015). ''Water Vapour'' [Online]. Available: http://climap.net/water-vapor</ref> In the past there has been debate over how severe an impact water vapour has on [[global warming]], but recently studies have confirmed that the amplification that water vapour has on heat is strong enough to double climate warming caused by increased CO<sub>2</sub> levels.<ref>Kathryn Hansen, NASA. (September 3, 2015). ''Water Vapor Confirmed as Major Player in Climate Change'' [Online]. Available: http://www.nasa.gov/topics/earth/features/vapor_warming.html</ref>

	As a greenhouse gas, water vapour serves as a [[positive feedback ~~mechanism~~]] for global warming. This means that the warmer the world gets, the more water vapour will exist in the air as evaporation rates from [[ocean]]s, lakes, and streams increase.<ref name=quest/> Since there is then more water vapour in the air, the water vapour itself contributes to more warming. Human activities do not increase the overall water vapour content in the atmosphere, but human activities can cause more water to evaporate as a result of increased temperature of the atmosphere. Thus [[anthropogenic]] warming is enhanced by a greater water vapour content in the atmosphere.<ref name=climap/>		As a greenhouse gas, water vapour serves creates a [[Positive climate feedback\|positive feedback cycle]] for global warming. This means that the warmer the world gets, the more water vapour will exist in the air as evaporation rates from [[ocean]]s, lakes, and streams increase.<ref name=quest/> Since there is then more water vapour in the air, the water vapour itself contributes to more warming. Human activities do not increase the overall water vapour content in the atmosphere, but human activities can cause more water to evaporate as a result of increased temperature of the atmosphere. Thus [[anthropogenic]] warming is enhanced by a greater water vapour content in the atmosphere.<ref name=climap/>

	==References==		==References==
	{{reflist}}		{{reflist}}[[Category:Uploaded]]

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[[Category:Done 2015-09-06]]
[[File:kettle-653673_640.jpg|360px|thumb|right|Figure 1. Although invisible, water vapour is one component of the steam released by a boiling kettle.<ref>Pixabay. (September 3, 2015). ''Kettle Steam'' [Online]. Available: https://pixabay.com/p-653673/?no_redirect</ref>]]

<onlyinclude>'''Water vapour''' is simply [[water]] that is present in its [[gas]]eous form instead of [[liquid]] form. It can be formed either through a process of [[evaporation]] or [[sublimation]]. Unlike [[cloud]]s, fog, or mist which are simply suspended particles of liquid water in the [[air]], water vapour itself cannot be seen because it is in gaseous form.</onlyinclude><ref name=climap/>

It is important to distinguish water vapour from [[steam]], as the two tend to be confused with each other as the difference between the two is not always clear. Both steam and water vapour are water in gaseous forms, but the [[temperature]] difference between the two is what sets them apart. Water vapour is gaseous water that is below its [[boiling point]], meaning that vapour can be condensed by increasing [[pressure]] without actually changing the temperature. Essentially, water vapour is ''cooler'' than steam, which is water vapour in gaseous form above its boiling point.

==Atmospheric Water Vapour==
Water vapour is important for a number of different reasons, but its presence in the [[atmosphere]] is one of the most important. Water vapour is present within the atmosphere in varying amounts but is a vital component of the [[hydrologic cycle]]. In the atmosphere, water vapour can exist in trace amounts or even make up as much as 4% of the atmosphere. This concentration depends largely on where the water vapour levels are measured. On average, the value of water vapour in the atmosphere is 2-3%. In arid or very cold locations - such as polar regions - the amount of water vapour in the air is much lower.<ref name=atm>The Weather Prediction. (September 3, 2015). ''Atmospheric Water Vapour'' [Online]. Available: http://www.theweatherprediction.com/habyhints/40/</ref>

Even on a clear day, water vapour exists in the atmosphere as an invisible gas - unlike clouds which are droplets of liquid water that can be seen. If the conditions are right, water vapour in the air can collect on small particles of dust, salt, or [[smoke]] in the air to form small droplets. These droplets gradually increase in size and over time become various forms of [[precipitation]]. Since water vapour is so prominent in the atmosphere and forms precipitation, water vapour is a major component of the hydrologic cycle. When [[water storage|water holding areas]] are heated by the [[Sun]], some of the water being held evaporates and becomes vapour, powering the cycle.<ref>USGS. (September 10, 2015). Precipitation - The Water Cycle [Online]. Available: http://water.usgs.gov/edu/watercycleprecipitation.html</ref>

In addition to being created by evaporating water, plants are capable of producing water vapour through a process of [[transpiration]].

==Product of Combustion==
When [[hydrocarbon]]s undergo [[combustion]], water is created by the chemical reactions. However, the high temperatures mean that the water is in its gaseous form: water vapour. An example of a hydrocarbon combustion reaction is shown below to illustrate how water is created during this process.

[[File:combustion_of_methane.jpg|800px|thumbnail|center|Figure 2. Methane combining with 2 oxygen to form carbon dioxide, two water molecules (in the form of water vapour) and heat.<ref name="image">American Chemical Society. (September 3, 2015). ''Methane and oxygen react'' [Online]. Available: http://www.middleschoolchemistry.com/multimedia/chapter6/lesson1, [October 25,2013]</ref>]]

Since water vapour is released when hydrocarbons are burned, water vapour is a fairly large component of the [[flue gas]]es released from [[coal]] fired [[power plant]]s or [[natural gas power plant]]s. A surprisingly large amount of water is released when coal is burned. For example, when burning [[bituminous coal]] roughly 0.4 [[kilogram]]s of water are produced for every kilogram of coal burned. This means that [[tonne]]s of water are be produced per hour at a large-scale coal fired power plant.

==Climate Impacts==
Water vapour moves across the Earth's surface, cycling through a variety of storage areas. It is this cycling that shapes the [[climate]] of different regions across the globe, providing precipitation and supporting life. As the climate changes, the distribution and cycling of water vapour changes as well.<ref name=quest>QUEST. (September 10, 2015). ''Water Vapour - Positive Feedback Cycle'' [Online]. Available: http://science.kqed.org/quest/2014/12/12/water-vapors-role-in-climate-change/</ref>

Water vapour is actually the most abundant [[greenhouse gas]] in the atmosphere, and the most potent of all the greenhouse gases as a result of its [[chemical]] structure. Its presence accounts for around two thirds of the natural [[greenhouse effect]].<ref name=climap>Climap. (September 3, 2015). ''Water Vapour'' [Online]. Available: http://climap.net/water-vapor</ref> In the past there has been debate over how severe an impact water vapour has on [[global warming]], but recently studies have confirmed that the amplification that water vapour has on heat is strong enough to double climate warming caused by increased CO<sub>2</sub> levels.<ref>Kathryn Hansen, NASA. (September 3, 2015). ''Water Vapor Confirmed as Major Player in Climate Change'' [Online]. Available: http://www.nasa.gov/topics/earth/features/vapor_warming.html</ref>

As a greenhouse gas, water vapour serves as a [[positive feedback mechanism]] for global warming. This means that the warmer the world gets, the more water vapour will exist in the air as evaporation rates from [[ocean]]s, lakes, and streams increase.<ref name=quest/> Since there is then more water vapour in the air, the water vapour itself contributes to more warming. Human activities do not increase the overall water vapour content in the atmosphere, but human activities can cause more water to evaporate as a result of increased temperature of the atmosphere. Thus [[anthropogenic]] warming is enhanced by a greater water vapour content in the atmosphere.<ref name=climap/>

==References==
{{reflist}}