This article is about the CERN experiment. For clouds in meteorology, see Cloud. For other uses, see Cloud (disambiguation).
Cosmics Leaving Outdoor Droplets (CLOUD)[1] is an experiment being run at CERN by a group of researchers led by Jasper Kirkby to investigate the microphysics between galactic cosmic rays (GCRs) and aerosols under controlled conditions. This is a fixed-target experiment that began operation in November 2009,[2] though it was originally proposed in 2000.[3]
The CLOUD experiment at CERN
The primary goal is to understand the influence of galactic cosmic rays (GCRs) on aerosols and clouds, and their implications for climate. Although its design is optimised to address the possibility of cosmic rays nucleating cloud particles, (as posed by, for example, Henrik Svensmark and colleagues[4]) CLOUD allows as well to measure aerosol nucleation and growth under controlled laboratory conditions. Atmospheric aerosols and their effect on clouds are recognised by the IPCC as the main source of uncertainty in present radiative forcing and climate models, since an increase in cloud cover reduces global warming.
The core of the experiment is a stainless steel chamber of 26 m3 volume filled with synthetic air made from liquid nitrogen and liquid oxygen. The chamber atmosphere and pressure is being measured and regulated by various instrumentations. The aerosol chamber can be exposed to an adjustable particle beam simulating GCRs at various altitude or latitude. UV illumination allows photolytic reaction. The chamber contains an electric field cage to control the drift of small ions and charged aerosols.[1] The ionisation produced by cosmic rays can be removed with a strong electric field. Besides, humidity and temperature inside the chamber can be regulated, allowing for fast adiabatic expansion for artificial clouds (compare cloud chamber) or experiments on ice microphysics. According to Kirkby "the level of cleanliness and control in a laboratory experiment is at the limit of current technology, and CERN know-how has been crucial for CLOUD being the first experiment to achieve this performance."[5]
Resultsedit
CERN posted a 2009 progress report on the CLOUD project.[6] J. Kirkby (2009) reviews developments in the CERN CLOUD project and planned tests. He describes cloud nucleation mechanisms which appear energetically favourable and depend on GCRs.[7][8]
On 24 August 2011, preliminary research published in the journal Nature showed there was a connection between Cosmic Rays and aerosol nucleation. Kirkby went on to say in the definitive CERN press Release "Ion-enhancement is particularly pronounced in the cool temperatures of the mid-troposphere and above, where CLOUD has found that sulphuric acid and water vapour can nucleate without the need for additional vapours.[9]
Process producing new aerosol particles
The first CLOUD experiments showed that sulphuric acid (derived from sulphur dioxide, for which fossil fuels are the predominant source) as such has a much smaller effect than had been assumed. In 2014, CLOUD researchers presented newer experimental results showing an interaction between oxidised biogenic vapours (e.g., alpha-pinene emitted by trees) and sulphuric acid. Ions produced in the atmosphere by galactic cosmic rays enhance the formation rate of these particles significantly, provided the concentrations of sulphuric acid and oxidised organic vapours are quite low. This new process may account for seasonal variations in atmospheric aerosol particles, which are being related to higher global tree emissions in the northern hemisphere summer.[5]
Besides biogenic vapours produced by plants, another class of trace vapours, amines have been shown by CLOUD to cluster with sulphuric acid to produce new aerosol particles in the atmosphere. These are found close to their primary sources, e.g. animal husbandry, while alpha-pinene is generally found over landmasses. The experiments show that sulfuric acid and oxidized organic vapors at low concentrations reproduce suitable particle nucleation rates. The nucleation mechanism used on global aerosol models yields a photochemically and biologically driven seasonal cycle of particle concentrations and cloud formation in good agreement with observations. CLOUD insofar allows to explain a large fraction of cloud seeds in the lower atmosphere involving sulphuric acid and biogenic aerosols.[10] CLOUD researchers note that cosmic rays have little influence on the formation of sulphuric acid–amine particle formation: "The ion-induced contribution is generally small, reflecting the high stability of sulphuric acid–dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation, except at low overall formation rates."[11] This result does not support the hypothesis that cosmic rays significantly affect climate, although a CERN press release states that neither does it "rule out a role for cosmic radiation" in climate.[12]
Dunne et al. (2016) have presented the main outcomes of 10 years of results obtained at the CLOUD experiment performed at CERN. They have studied in detail the physico-chemical mechanisms and the kinetics of aerosols formation. The nucleation process of water droplets/ice micro-crystals from water vapor reproduced in the CLOUD experiment and also directly observed in the Earth atmosphere do not only involve ions formation due to cosmic rays but also a range of complex chemical reactions with sulfuric acid, ammonia and organic compounds emitted in the air by human activities and by organisms living on land or in the oceans (plankton).[13] Although they observe that a fraction of cloud nuclei is effectively produced by ionisation due to the interaction of cosmic rays with the constituents of Earth atmosphere, this process is insufficient to attribute all of the present climate modifications to the fluctuations of the cosmic rays intensity modulated by changes in the solar activity and Earth magnetosphere.
^CLOUD experiment provides unprecedented insight into cloud formation, CERN
^The Cloud Collaboration (2001-04-16). "A study of the link between cosmic rays and clouds with a cloud chamber at the CERN PS". arXiv:physics/0104048.
^Svensmark, Henrik; Friis-Christensen, Eigil (1997-07-01). "Variation of cosmic ray flux and global cloud coverage—a missing link in solar-climate relationships". Journal of Atmospheric and Solar-Terrestrial Physics. 59 (11): 1225–1232. Bibcode:1997JASTP..59.1225S. doi:10.1016/S1364-6826(97)00001-1. ISSN 1364-6826.
^ ab"CERN experiment sheds new light on cloud formation | CERN". home.cern. Dan Noyes. 16 May 2014. Retrieved 2015-12-02.
^2009 Progress report on PS215/CLOUD Kirkby, Jasper, The CLOUD Collaboration, CERN, Geneva, SPS and PS Experiments Committee, CERN-SPSC-2010-013, April 7, 2010
^Cosmic Rays and Climate Video Jasper Kirkby, CERN Colloquium, 4 June 2009
^Cosmic Rays and Climate Presentation Jasper Kirkby, CERN Colloquium, 4 June 2009
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This article is about the CERN experiment For clouds in meteorology see Cloud For other uses see Cloud disambiguation Cosmics Leaving Outdoor Droplets CLOUD 1 is an experiment being run at CERN by a group of researchers led by Jasper Kirkby to investigate the microphysics between galactic cosmic rays GCRs and aerosols under controlled conditions This is a fixed target experiment that began operation in November 2009 2 though it was originally proposed in 2000 3 The CLOUD experiment at CERN The primary goal is to understand the influence of galactic cosmic rays GCRs on aerosols and clouds and their implications for climate Although its design is optimised to address the possibility of cosmic rays nucleating cloud particles as posed by for example Henrik Svensmark and colleagues 4 CLOUD allows as well to measure aerosol nucleation and growth under controlled laboratory conditions Atmospheric aerosols and their effect on clouds are recognised by the IPCC as the main source of uncertainty in present radiative forcing and climate models since an increase in cloud cover reduces global warming Contents 1 Setup 2 Results 3 References 4 External linksSetup edit nbsp View inside the chamber of the CLOUD experiment The core of the experiment is a stainless steel chamber of 26 m3 volume filled with synthetic air made from liquid nitrogen and liquid oxygen The chamber atmosphere and pressure is being measured and regulated by various instrumentations The aerosol chamber can be exposed to an adjustable particle beam simulating GCRs at various altitude or latitude UV illumination allows photolytic reaction The chamber contains an electric field cage to control the drift of small ions and charged aerosols 1 The ionisation produced by cosmic rays can be removed with a strong electric field Besides humidity and temperature inside the chamber can be regulated allowing for fast adiabatic expansion for artificial clouds compare cloud chamber or experiments on ice microphysics According to Kirkby the level of cleanliness and control in a laboratory experiment is at the limit of current technology and CERN know how has been crucial for CLOUD being the first experiment to achieve this performance 5 Results editCERN posted a 2009 progress report on the CLOUD project 6 J Kirkby 2009 reviews developments in the CERN CLOUD project and planned tests He describes cloud nucleation mechanisms which appear energetically favourable and depend on GCRs 7 8 On 24 August 2011 preliminary research published in the journal Nature showed there was a connection between Cosmic Rays and aerosol nucleation Kirkby went on to say in the definitive CERN press Release Ion enhancement is particularly pronounced in the cool temperatures of the mid troposphere and above where CLOUD has found that sulphuric acid and water vapour can nucleate without the need for additional vapours 9 nbsp Process producing new aerosol particles The first CLOUD experiments showed that sulphuric acid derived from sulphur dioxide for which fossil fuels are the predominant source as such has a much smaller effect than had been assumed In 2014 CLOUD researchers presented newer experimental results showing an interaction between oxidised biogenic vapours e g alpha pinene emitted by trees and sulphuric acid Ions produced in the atmosphere by galactic cosmic rays enhance the formation rate of these particles significantly provided the concentrations of sulphuric acid and oxidised organic vapours are quite low This new process may account for seasonal variations in atmospheric aerosol particles which are being related to higher global tree emissions in the northern hemisphere summer 5 Besides biogenic vapours produced by plants another class of trace vapours amines have been shown by CLOUD to cluster with sulphuric acid to produce new aerosol particles in the atmosphere These are found close to their primary sources e g animal husbandry while alpha pinene is generally found over landmasses The experiments show that sulfuric acid and oxidized organic vapors at low concentrations reproduce suitable particle nucleation rates The nucleation mechanism used on global aerosol models yields a photochemically and biologically driven seasonal cycle of particle concentrations and cloud formation in good agreement with observations CLOUD insofar allows to explain a large fraction of cloud seeds in the lower atmosphere involving sulphuric acid and biogenic aerosols 10 CLOUD researchers note that cosmic rays have little influence on the formation of sulphuric acid amine particle formation The ion induced contribution is generally small reflecting the high stability of sulphuric acid dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation except at low overall formation rates 11 This result does not support the hypothesis that cosmic rays significantly affect climate although a CERN press release states that neither does it rule out a role for cosmic radiation in climate 12 Dunne et al 2016 have presented the main outcomes of 10 years of results obtained at the CLOUD experiment performed at CERN They have studied in detail the physico chemical mechanisms and the kinetics of aerosols formation The nucleation process of water droplets ice micro crystals from water vapor reproduced in the CLOUD experiment and also directly observed in the Earth atmosphere do not only involve ions formation due to cosmic rays but also a range of complex chemical reactions with sulfuric acid ammonia and organic compounds emitted in the air by human activities and by organisms living on land or in the oceans plankton 13 Although they observe that a fraction of cloud nuclei is effectively produced by ionisation due to the interaction of cosmic rays with the constituents of Earth atmosphere this process is insufficient to attribute all of the present climate modifications to the fluctuations of the cosmic rays intensity modulated by changes in the solar activity and Earth magnetosphere References edit a b CLOUD official website CLOUD experiment provides unprecedented insight into cloud formation CERN The Cloud Collaboration 2001 04 16 A study of the link between cosmic rays and clouds with a cloud chamber at the CERN PS arXiv physics 0104048 Svensmark Henrik Friis Christensen Eigil 1997 07 01 Variation of cosmic ray flux and global cloud coverage a missing link in solar climate relationships Journal of Atmospheric and Solar Terrestrial Physics 59 11 1225 1232 Bibcode 1997JASTP 59 1225S doi 10 1016 S1364 6826 97 00001 1 ISSN 1364 6826 a b CERN experiment sheds new light on cloud formation CERN home cern Dan Noyes 16 May 2014 Retrieved 2015 12 02 2009 Progress report on PS215 CLOUD Kirkby Jasper The CLOUD Collaboration CERN Geneva SPS and PS Experiments Committee CERN SPSC 2010 013 April 7 2010 Cosmic Rays and Climate Video Jasper Kirkby CERN Colloquium 4 June 2009 Cosmic Rays and Climate Presentation Jasper Kirkby CERN Colloquium 4 June 2009 Kirkby Jasper Curtius Joachim Almeida Joao Dunne Eimear Duplissy Jonathan Ehrhart Sebastian Franchin Alessandro Gagne Stephanie Ickes Luisa Kurten Andreas Kupc Agnieszka Metzger Axel Riccobono Francesco Rondo Linda Schobesberger Siegfried Tsagkogeorgas Georgios Wimmer Daniela Amorim Antonio Bianchi Federico Breitenlechner Martin David Andre Dommen Josef Downard Andrew Ehn Mikael Flagan Richard C Haider Stefan Hansel Armin Hauser Daniel Jud Werner Junninen Heikki Kreissl Fabian Kvashin Alexander Laaksonen Ari Lehtipalo Katrianne Lima Jorge Lovejoy Edward R Makhmutov Vladimir Mathot Serge Mikkila Jyri Minginette Pierre Mogo Sandra Nieminen Tuomo Onnela Antti Pereira Paulo Petaja Tuukka Schnitzhofer Ralf Seinfeld John H Sipila Mikko Stozhkov Yuri Stratmann Frank Tome Antonio Vanhanen Joonas Viisanen Yrjo Vrtala Aron Wagner Paul E Walther Hansueli Weingartner Ernest Wex Heike Winkler Paul M Carslaw Kenneth S Worsnop Douglas R Baltensperger Urs Kulmala Markku 2011 08 25 Role of sulphuric acid ammonia and galactic cosmic rays in atmospheric aerosol nucleation PDF Nature 476 7361 429 433 Bibcode 2011Natur 476 429K doi 10 1038 nature10343 ISSN 0028 0836 PMID 21866156 S2CID 4326159 Riccobono Francesco Schobesberger Siegfried Scott Catherine E Dommen Josef Ortega Ismael K Rondo Linda Almeida Joao Amorim Antonio Bianchi Federico 2014 05 16 Oxidation products of biogenic emissions contribute to nucleation of atmospheric particles Science 344 6185 717 721 Bibcode 2014Sci 344 717R doi 10 1126 science 1243527 ISSN 0036 8075 PMID 24833386 S2CID 206551402 Almeida et al 2013 Molecular understanding of sulphuric acid amine particle nucleation in the atmosphere Nature 502 359 363 At http www readcube com articles 10 1038 nature12663 CERN s CLOUD experiment shines new light on climate change Dunne E M Gordon H Kurten A Almeida J Duplissy J Williamson C Ortega I K Pringle K J Adamov A Baltensperger U Barmet P Benduhn F Bianchi F Breitenlechner M Clarke A Curtius J Dommen J Donahue N M Ehrhart S Flagan R C Franchin A Guida R Hakala J Hansel A Heinritzi M Jokinen T Kangasluoma J Kirkby J Kulmala M Kupc A Lawler M J Lehtipalo K Makhmutov V Mann G Mathot S Merikanto J Miettinen P Nenes A Onnela A Rap A Reddington C L S Riccobono F Richards N A D Rissanen M P Rondo L Sarnela N Schobesberger S Sengupta K Simon M Sipila M Smith J N Stozkhov Y Tome A Trostl J Wagner P E Wimmer D Winkler P M Worsnop D R Carslaw K S 2016 12 02 Global atmospheric particle formation from CERN CLOUD measurements PDF Science 354 6316 1119 1124 Bibcode 2016Sci 354 1119D doi 10 1126 science aaf2649 ISSN 0036 8075 PMID 27789796 S2CID 9426269 External links editTED CERN Project website Archived 2014 07 25 at the Wayback Machine CLOUD experiment record on INSPIRE HEP Retrieved from https en wikipedia org w index php title CLOUD experiment amp oldid 1219287063, wikipedia, wiki, book, books, library,
