Geothermal gradient - Revision history

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	[[File:Blender3D_EarthQuarterCut.jpg\|thumb\|300px\|Figure 1. The Earth gets hotter as one travels towards the core, known as the geothermal gradient.<ref>Wikimedia Commons [Online], Available: https://commons.wikimedia.org/wiki/File:Blender3D_EarthQuarterCut.jpg</ref>]]		[[File:Blender3D_EarthQuarterCut.jpg\|thumb\|300px\|Figure 1. The Earth gets hotter as one travels towards the core, known as the geothermal gradient.<ref>Wikimedia Commons [Online], Available: https://commons.wikimedia.org/wiki/File:Blender3D_EarthQuarterCut.jpg</ref>]]

	<onlyinclude>'''~~Geothermal~~ gradient''' is the amount the Earth’s [[temperature]] increases with depth~~, indicating~~ [[heat]] ﬂowing from the Earth’s [[cross section of the Earth\|warm interior]] to its surface.</onlyinclude><ref name=IPCC_SRREN> Verbruggen, A., W. Moomaw, J. Nyboer, 2011: Annex I: Glossary, Acronyms, Chemical Symbols and Preﬁxes. In IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation [O. Edenhofer, R. Pichs- Madruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P. Eickemeier, G. Hansen, S. Schlömer, C. von Stechow (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.</ref> '''On average''', the temperature increases by about '''[[celsius\|25°C]]''' for every [[kilometer]] of depth.<ref name=wolf>R. Wolfson, "Energy from Earth and Moon" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 8, pp. 204-224</ref> This difference in temperatures drives the [[geothermal energy]] ~~flows~~ and allows humans to use this energy for [[geothermal district heating\|heating]] and [[geothermal electricity\|electricity generation]]. There are a number of places on the planet where the temperature changes quite a bit faster though, and ~~that's~~ almost always where [[geothermal energy]] is the most viable.		<onlyinclude>The '''geothermal gradient''' is the amount that the Earth’s [[temperature]] increases with depth. It indicates [[heat]] ﬂowing from the Earth’s [[cross section of the Earth\|warm interior]] to its surface.</onlyinclude><ref name=IPCC_SRREN> Verbruggen, A., W. Moomaw, J. Nyboer, 2011: Annex I: Glossary, Acronyms, Chemical Symbols and Preﬁxes. In IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation [O. Edenhofer, R. Pichs- Madruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P. Eickemeier, G. Hansen, S. Schlömer, C. von Stechow (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.</ref> '''On average''', the temperature increases by about '''[[celsius\|25°C]]''' for every [[kilometer]] of depth.<ref name=wolf>R. Wolfson, "Energy from Earth and Moon" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 8, pp. 204-224</ref> This difference in temperatures drives the flow of [[geothermal energy]] and allows humans to use this energy for [[geothermal district heating\|heating]] and [[geothermal electricity\|electricity generation]]. There are a number of places on the planet where the temperature changes quite a bit faster though, and those locations are almost always where [[geothermal energy]] is the most viable.

	The [[cross section of the Earth\|interior of the Earth]] is extremely hot, and ~~even~~ reaches [[temperature]]s of over [[celsius\|5000°C]] ~~towards~~ the core, not much colder than the surface of the [[Sun]] (the [[Nuclear fusion in the Sun\|interior of the sun]] however is ''much'' hotter).<ref>D. Alfè; M. Gillan & G. D. Price (January 30, 2002). "Composition and temperature of the Earth's core constrained by combining ab initio calculations and seismic data" (PDF). Earth and Planetary Science Letters (Elsevier) 195 (1–2): 91–98. Bibcode:2002E&PSL.195...91A. doi:10.1016/S0012-821X(01)00568-4.</ref> In the 19th century it was predicted that the Earth should have cooled off just millions of years after its formation because of [[heat transfer mechanisms]],<ref>J.D. Burchfield, ''Lord Kelvin and the Age of the Earth'', University of Chicago Press, 1990.</ref> but the [[Timescale of the universe\|Earth has been around]] for thousands of times longer than that.		The [[cross section of the Earth\|interior of the Earth]] is extremely hot, and reaches [[temperature]]s over [[celsius\|5000°C]] near the core, which is not much colder than the surface of the [[Sun]] (the [[Nuclear fusion in the Sun\|interior of the sun]] however is ''much'' hotter).<ref>D. Alfè; M. Gillan & G. D. Price (January 30, 2002). "Composition and temperature of the Earth's core constrained by combining ab initio calculations and seismic data" (PDF). Earth and Planetary Science Letters (Elsevier) 195 (1–2): 91–98. Bibcode:2002E&PSL.195...91A. doi:10.1016/S0012-821X(01)00568-4.</ref>

	==Where ~~does this~~ heat ~~come~~ from?==		==Where is the heat from?==

	It was discovered in the early 20th century that the Earth's underground heat is from [[radioactive]] elements. Specifically, ~~this~~ heating is caused by the [[radioactive decay\|decay]] of [[element]]s such as [[potassium]], [[uranium]] and [[thorium]]. These elements ~~aren't~~ found in the core however, with the most popular model suggesting that they are found in the '''lithosphere''' and '''mantle'''. This form of heating is said to account for 50% of the Earth's heat, with the other heat coming from the primordial heat of the Earth (heat from the Earth's formation).<ref>Physics World. (2011). ''Radioactive decay accounts for half of Earth's heat'' [Online] Available: http://physicsworld.com/cws/article/news/2011/jul/19/radioactive-decay-accounts-for-half-of-earths-heat</ref>		It was discovered in the early 20th century that the Earth's underground heat is from [[radioactive]] elements. Specifically, geothermal heating is caused by the [[radioactive decay\|decay]] of [[element]]s such as [[potassium]], [[uranium]] and [[thorium]]. These elements are not found in the core however, with the most popular model suggesting that they are found in the '''lithosphere''' and '''mantle'''. This form of heating is said to account for 50% of the Earth's heat, with the other heat coming from the primordial heat of the Earth (heat from the Earth's formation that has been trapped in the planet).<ref>Physics World. (2011). ''Radioactive decay accounts for half of Earth's heat'' [Online] Available: http://physicsworld.com/cws/article/news/2011/jul/19/radioactive-decay-accounts-for-half-of-earths-heat</ref>

	Figures 2 and 3 below shows ~~the~~ temperature ~~increase with depth~~, along with ~~how this~~ heat ~~flows~~. ~~It can be seen that there is a~~ drastic ~~increase~~ in the lithosphere~~/mantle due to~~ the ~~radioactive isotopes, and then it becomes rather steady towards the core~~.		Figures 2 and 3 below shows how temperature decreases as it approaches Earth's surface, along with the mechanisms of heat flow. Overall, temperature changes are gradual except near the base of the mantle where drastic compositional changes occur, and in the lithosphere where the presence of fluids has a large effect.

	<gallery mode="packed" caption="Earth's Temperature Gradient" widths="250px" heights="320px" >		<gallery mode="packed" caption="Earth's Temperature Gradient" widths="250px" heights="320px" >
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	</gallery>		</gallery>

	==~~See also~~==		==For Further Reading==

	*[[Geothermal electricity]]		*[[Geothermal electricity]]
	*[[Geothermal energy]]		*[[Geothermal energy]]
	*[[Ground source heat pump]]		*[[Ground source heat pump]]
	*[[Geothermal district heating]]		*[[Geothermal district heating]]
			*Or explore a [[Special:Random\|random page]]

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

J.williams: 1 revision imported

2015-08-26T21:31:52Z

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J.williams at 18:50, 24 August 2015

2015-08-24T18:50:42Z

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[[Category:Done 2015-08-21]]
[[File:Blender3D_EarthQuarterCut.jpg|thumb|300px|Figure 1. The Earth gets hotter as one travels towards the core, known as the geothermal gradient.<ref>Wikimedia Commons [Online], Available: https://commons.wikimedia.org/wiki/File:Blender3D_EarthQuarterCut.jpg</ref>]]

<onlyinclude>'''Geothermal gradient''' is the amount the Earth’s [[temperature]] increases with depth, indicating [[heat]] ﬂowing from the Earth’s [[cross section of the Earth|warm interior]] to its surface.</onlyinclude><ref name=IPCC_SRREN> Verbruggen, A., W. Moomaw, J. Nyboer, 2011: Annex I: Glossary, Acronyms, Chemical Symbols and Preﬁxes. In IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation [O. Edenhofer, R. Pichs- Madruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P. Eickemeier, G. Hansen, S. Schlömer, C. von Stechow (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.</ref> '''On average''', the temperature increases by about '''[[celsius|25°C]]''' for every [[kilometer]] of depth.<ref name=wolf>R. Wolfson, "Energy from Earth and Moon" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 8, pp. 204-224</ref> This difference in temperatures drives the [[geothermal energy]] flows and allows humans to use this energy for [[geothermal district heating|heating]] and [[geothermal electricity|electricity generation]]. There are a number of places on the planet where the temperature changes quite a bit faster though, and that's almost always where [[geothermal energy]] is the most viable.

The [[cross section of the Earth|interior of the Earth]] is extremely hot, and even reaches [[temperature]]s of over [[celsius|5000°C]] towards the core, not much colder than the surface of the [[Sun]] (the [[Nuclear fusion in the Sun|interior of the sun]] however is ''much'' hotter).<ref>D. Alfè; M. Gillan & G. D. Price (January 30, 2002). "Composition and temperature of the Earth's core constrained by combining ab initio calculations and seismic data" (PDF). Earth and Planetary Science Letters (Elsevier) 195 (1–2): 91–98. Bibcode:2002E&PSL.195...91A. doi:10.1016/S0012-821X(01)00568-4.</ref> In the 19th century it was predicted that the Earth should have cooled off just millions of years after its formation because of [[heat transfer mechanisms]],<ref>J.D. Burchfield, ''Lord Kelvin and the Age of the Earth'', University of Chicago Press, 1990.</ref> but the [[Timescale of the universe|Earth has been around]] for thousands of times longer than that.

==Where does this heat come from?==

It was discovered in the early 20th century that the Earth's underground heat is from [[radioactive]] elements. Specifically, this heating is caused by the [[radioactive decay|decay]] of [[element]]s such as [[potassium]], [[uranium]] and [[thorium]]. These elements aren't found in the core however, with the most popular model suggesting that they are found in the '''lithosphere''' and '''mantle'''. This form of heating is said to account for 50% of the Earth's heat, with the other heat coming from the primordial heat of the Earth (heat from the Earth's formation).<ref>Physics World. (2011). ''Radioactive decay accounts for half of Earth's heat'' [Online] Available: http://physicsworld.com/cws/article/news/2011/jul/19/radioactive-decay-accounts-for-half-of-earths-heat</ref>

Figures 2 and 3 below shows the temperature increase with depth, along with how this heat flows. It can be seen that there is a drastic increase in the lithosphere/mantle due to the radioactive isotopes, and then it becomes rather steady towards the core.

<gallery mode="packed" caption="Earth's Temperature Gradient" widths="250px" heights="320px" >
File:Temperature_schematic_of_inner_Earth.jpg|Figure 2. Temperature profile of the Earth's layers. Temperature increases with depth.<ref>Wikimedia Commons [Online], Available: https://commons.wikimedia.org/wiki/File:Temperature_schematic_of_inner_Earth.jpg#/media/File:Temperature_schematic_of_inner_Earth.jpg</ref>
File:Heat_flow_of_the_inner_earth.jpg|Figure 3. Heat transfer mechanisms within the Earth, along with the % amount of heat flow in each layer.<Ref>Wikimedia Commons [Online], Available: https://commons.wikimedia.org/wiki/File:Heat_flow_of_the_inner_earth.jpg#/media/File:Heat_flow_of_the_inner_earth.jpg</ref>
</gallery>

==See also==

*[[Geothermal electricity]]
*[[Geothermal energy]]
*[[Ground source heat pump]]
*[[Geothermal district heating]]

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