Editing Temperature gradient

{{Short description|Temperature difference per unit of length}}
A '''temperature gradient''' is a [[physical quantity]] that describes in which direction and at what rate the [[temperature]] changes the most rapidly around a particular location. The temperature [[spatial gradient]] is a [[vector quantity]] with [[Dimensional analysis|dimension]] of temperature difference per unit [[length]]. The [[International System of Units|SI]] [[Units of measurement|unit]] is [[kelvin]] per [[meter]] (K/m).

Temperature gradients in the [[Earth's atmosphere|atmosphere]] are important in the atmospheric sciences ([[meteorology]], [[climatology]] and related fields).

== Mathematical description ==
Assuming that the temperature ''T'' is an [[intensive quantity]], i.e., a single-valued, [[Continuous function|continuous]] and [[Derivative|differentiable]] [[Function (mathematics)|function]] of three-dimensional space (often called a [[scalar field]]), i.e., that

:<math>T=T(x,y,z)</math>

where ''x'', ''y'' and ''z'' are the [[Cartesian coordinate system|coordinates]] of the location of interest, then the temperature gradient is the [[vector (geometric)|vector]] quantity defined as

:<math>\nabla T = \begin{pmatrix}
{\frac{\partial T}{\partial x}},  
{\frac{\partial T}{\partial y}}, 
{\frac{\partial T}{\partial z}}
\end{pmatrix}</math>

== Physical processes ==

=== Meteorology ===
Differences in air temperature between different locations are critical in weather forecasting and climate. The absorption of solar light at or near the planetary surface increases the temperature gradient and may result in [[convection]] (a major process of [[cloud]] formation, often associated with [[Precipitation (meteorology)|precipitation]]). 
[[Surface weather analysis|Meteorological fronts]] are regions where the horizontal temperature gradient may reach relatively high values, as these are boundaries between [[air mass]]es with rather distinct properties.

Clearly, the temperature gradient may change substantially in time, as a result of diurnal or seasonal heating and cooling for instance. This most likely happens during an [[Inversion (meteorology)|inversion]]. For instance, during the day the temperature at [[Lithosphere|ground level]] may be cold while it's warmer up in the atmosphere. As the day shifts over to night the temperature might drop rapidly while at other places on the land stay warmer or cooler at the same [[elevation]]. This happens on the [[West Coast of the United States]] sometimes due to geography.

=== Weathering ===
Expansion and contraction of rock, caused by temperature changes during a [[wildfire]], through [[Weathering#Thermal stress|thermal stress weathering]], may result in [[thermal shock]] and subsequent structure failure.

== Indoor temperature ==
{{Main|Thermal destratification in buildings}}
{{empty section|date=December 2022}}

== See also ==
* [[Atmospheric temperature]] for gradient of Earth's atmosphere
* [[Geothermal gradient]]
* [[Gradient]]
* [[Lapse rate]]
* [[Weak temperature gradient approximation]]

== References ==
* {{cite book|author=Edward N. Lorenz|title=The Nature and Theory of the General Circulation of the Atmosphere|url=https://archive.org/details/naturetheoryofge0000lore|url-access=registration|series=Publication No. 218|year=1967|publisher=World Meteorological Organization|location=Geneva, Switzerland}}
* {{cite book|author=M. I. Budyko|year=1978|title=Climate and Life|url=https://archive.org/details/climatelife00mibu|publisher=Academic Press|series=International Geophysics Series|volume=18|isbn=0-12-139450-6|url-access=registration}}
* {{cite book|title=An introduction to atmospheric physics|url=https://books.google.com/books?id=6oIuAAAAIAAJ|author1=Robert G. Fleagle|author2=Joost A. Businger|author2-link=Joost A. Businger|date=1980|publisher=Academic Press|series=International Geophysics Series|volume=25|isbn=0-12-260355-9}}
* {{cite book|author=David Miller|title=Energy at the surface of the earth : an introduction to the energetics of ecosystems|url=https://archive.org/details/energyatsurfaceo0000mill|url-access=registration|year=1981|publisher=Academic Press|isbn=978-0-08-095460-8}}
* {{cite book|author1=John M. Wallace|author2=Peter V. Hobbs|title=Atmospheric Science: An Introductory Survey|url=https://books.google.com/books?id=HZ2wNtDOU0oC|year=2006|publisher=Elsevier|isbn=978-0-08-049953-6}}
{{Reflist}}

==External links==
* [http://www.grida.no/climate/ipcc_tar/wg1/index.htm IPCC Third Assessment Report]
* [http://visualdaq.com/DaqPlaner/ Pictorial Representation of Temperature Gradient (Tools)].

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[[Category:Atmospheric dynamics]]
[[Category:Climatology]]
[[Category:Spatial gradient]]
[[Category:Temperature]]
[[Category:Physical quantities]]

[[fr:Gradient#Gradient de température]]