[{"@context":"http:\/\/schema.org\/","@type":"BlogPosting","@id":"https:\/\/wiki.edu.vn\/en\/vapour-pressure-deficit-wikipedia\/#BlogPosting","mainEntityOfPage":"https:\/\/wiki.edu.vn\/en\/vapour-pressure-deficit-wikipedia\/","headline":"Vapour-pressure deficit – Wikipedia","name":"Vapour-pressure deficit – Wikipedia","description":"before-content-x4 From Wikipedia, the free encyclopedia Global distribution of Vapour-pressure deficit averaged over the years 1981-2010 from the CHELSA-BIOCLIM+ data","datePublished":"2014-01-26","dateModified":"2014-01-26","author":{"@type":"Person","@id":"https:\/\/wiki.edu.vn\/en\/author\/lordneo\/#Person","name":"lordneo","url":"https:\/\/wiki.edu.vn\/en\/author\/lordneo\/","image":{"@type":"ImageObject","@id":"https:\/\/secure.gravatar.com\/avatar\/cd810e53c1408c38cc766bc14e7ce26a?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/cd810e53c1408c38cc766bc14e7ce26a?s=96&d=mm&r=g","height":96,"width":96}},"publisher":{"@type":"Organization","name":"Enzyklop\u00e4die","logo":{"@type":"ImageObject","@id":"https:\/\/wiki.edu.vn\/wiki4\/wp-content\/uploads\/2023\/08\/download.jpg","url":"https:\/\/wiki.edu.vn\/wiki4\/wp-content\/uploads\/2023\/08\/download.jpg","width":600,"height":60}},"image":{"@type":"ImageObject","@id":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/2\/2e\/VPD_wiki.png\/220px-VPD_wiki.png","url":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/2\/2e\/VPD_wiki.png\/220px-VPD_wiki.png","height":"157","width":"220"},"url":"https:\/\/wiki.edu.vn\/en\/vapour-pressure-deficit-wikipedia\/","wordCount":3196,"articleBody":"     (adsbygoogle = window.adsbygoogle || []).push({});before-content-x4From Wikipedia, the free encyclopedia  Global distribution of Vapour-pressure deficit averaged over the years 1981-2010 from the CHELSA-BIOCLIM+ data set[1]       (adsbygoogle = window.adsbygoogle || []).push({});after-content-x4Vapour-pressure deficit, or VPD, is the difference (deficit) between the amount of moisture in the air and how much moisture the air can hold when it is saturated.  Once air becomes saturated, water will condense out to form clouds, dew or films of water over leaves.  It is this last instance that makes VPD important for greenhouse regulation.  If a film of water forms on a plant leaf, it becomes far more susceptible to rot.  On the other hand, as the VPD increases, the plant needs to draw more water from its roots. In the case of cuttings, the plant may dry out and die.  For this reason the ideal range for VPD in a greenhouse is from 0.45\u00a0kPa to 1.25\u00a0kPa, ideally sitting at around 0.85\u00a0kPa.  As a general rule, most plants grow well at VPDs of between 0.8 and 0.95\u00a0kPa.[citation needed]       (adsbygoogle = window.adsbygoogle || []).push({});after-content-x4In ecology, it is the difference between the actual water vapour pressure and the saturation water vapour pressure at a particular temperature. Unlike relative humidity, vapour-pressure deficit has a simple nearly straight-line relationship to the rate of evapotranspiration and other measures of evaporation.Table of ContentsComputing VPD for plants in a greenhouse[edit]Climate[edit]Application in contexts of wildfire[edit]See also[edit]References[edit]Computing VPD for plants in a greenhouse[edit]To compute the VPD,[2] we need the ambient (greenhouse) air temperature, the relative humidity and, if possible, the canopy air temperature.  We must then compute the saturation pressure.  Saturation pressure can be looked up in a psychrometric chart or derived from the Arrhenius equation; a way to compute it directly from temperature is       (adsbygoogle = window.adsbygoogle || []).push({});after-content-x4vpsat=eA\/T+B+CT+DT2+ET3+Fln\u2061T,{displaystyle vp_{text{sat}}=e^{A\/T+B+CT+DT^{2}+ET^{3}+Fln T},}where:vpsat{displaystyle vp_{text{sat}}} is the saturation vapor pressure in PSI,A=\u22121.0440397\u00d7104{displaystyle A=-1.0440397times 10^{4}},B=\u221211.29465{displaystyle B=-11.29465},C=\u22122.7022355\u00d710\u22122{displaystyle C=-2.7022355times 10^{-2}},D=1.289036\u00d710\u22125{displaystyle D=1.289036times 10^{-5}},E=\u22122.4780681\u00d710\u22129{displaystyle E=-2.4780681times 10^{-9}},F=6.5459673{displaystyle F=6.5459673},T{displaystyle T} is temperature of the air in the Rankine scale.To convert between Rankine and degrees Fahrenheit:T[R]=T[\u2218F]+459.67{displaystyle T[{text{R}}]=T[^{circ }{text{F}}]+459.67}We compute this pressure for both the ambient and canopy temperatures.We then can compute the actual partial pressure of the water vapour in the air by multiplying by the relative humidity [%]:vpair=vpsat\u00d7(relative humidity)\/100{displaystyle vp_{text{air}}=vp_{text{sat}}times ({text{relative humidity}})\/100}and finally VPD using vpsat\u2212vpair{displaystyle vp_{text{sat}}-vp_{text{air}}} orvpcanopy sat\u2212vpair{displaystyle vp_{text{canopy sat}}-vp_{text{air}}}when the canopy temperature is known.Or simplyVPD=vpsat\u00d7(1\u2212relative humidity\/100){displaystyle VPD=vp_{text{sat}}times (1-{text{relative humidity}}\/100)}Climate[edit]VPD can be a limiting factor in plant growth. Climate change is predicted to increase the importance of VPD in plant growth, and will further limit growth rates across ecosystems.[3]Application in contexts of wildfire[edit]The vapour pressure deficit can be utilized when predicting behaviour of a wildfire. Such predictions are an essential tool of wildfire suppression.[4]See also[edit]References[edit]^ Brun, P., Zimmermann, N.E., Hari, C., Pellissier, L., Karger, D.N. (preprint): Global climate-related predictors at kilometre resolution for the past and future. Earth Syst. Sci. Data Discuss. https:\/\/doi.org\/10.5194\/essd-2022-212^ “Greenhouse Condensation Control: Understanding and Using Vapor Pressure Deficit (VPD)”. Ohio State University Extension Fact Sheet. Retrieved November 7, 2017.^ Novick, Kimberly A.; Ficklin, Darren L.; Stoy, Paul C.; Williams, Christopher A.; Bohrer, Gil; Oishi, A. Christopher; Papuga, Shirley A.; Blanken, Peter D.; Noormets, Asko; Sulman, Benjamin N.; Scott, Russell L. (November 2016). “The increasing importance of atmospheric demand for ecosystem water and carbon fluxes”. Nature Climate Change. 6 (11): 1023\u20131027. doi:10.1038\/nclimate3114. hdl:10150\/622526. ISSN\u00a01758-6798.^ Gabbert, Bill (26 January 2015). “The role of vapor pressure deficit in wildland fire”. Wildfire Today. Retrieved 24 August 2020.     (adsbygoogle = window.adsbygoogle || []).push({});after-content-x4"},{"@context":"http:\/\/schema.org\/","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"https:\/\/wiki.edu.vn\/en\/#breadcrumbitem","name":"Enzyklop\u00e4die"}},{"@type":"ListItem","position":2,"item":{"@id":"https:\/\/wiki.edu.vn\/en\/vapour-pressure-deficit-wikipedia\/#breadcrumbitem","name":"Vapour-pressure deficit – Wikipedia"}}]}]