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CLOUD un experimento del CERN ofrece nuevas pistas sobre la formación de nubes

El experimento CLOUD del CERN (Organización Europea para la Investigación Nuclear) publicó el jueves 25 de agosto en la revista Nature los primeros resultados de su investigación. Este experimento ha sido diseñado para estudiar en condiciones de laboratorio el efecto de los rayos cósmicos, partículas subatómicas de alta energía procedentes del espacio exterior, en la formación de aerosoles atmosféricos, diminutas partículas líquidas o sólidas suspendidas en la atmósfera. Se cree que los aerosoles atmosféricos son responsables de una gran parte de las agrupaciones de moléculas que forman las gotas de las nubes, por lo que entender el proceso de formación de aerosoles es importante para entender el clima.

Los resultados de CLOUD muestran que los rastros de vapores que hasta ahora eran considerados responsables de la formación de aerosoles en la parte más baja de la atmósfera pueden explicar sólo una pequeña fracción de la producción de aerosoles atmosféricos. Los resultados muestran también que la ionización producida por los rayos cósmicos aumenta significativamente la formación de aerosoles. Mediciones precisas como éstas son importantes para lograr una comprensión cuantitativa de la formación de nubes, y contribuirá a una mejor evaluación de los efectos de las nubes en los modelos climáticos.

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“Estos nuevos resultados son importantes porque hemos hecho primeras observaciones de algunos procesos atmosféricos muy importantes”, dijo el portavoz del experimento, Jasper Kirkby. “Hemos encontrado que los rayos cósmicos aumentan significativamente la formación de partículas de aerosoles en la troposfera media y superior, aerosoles que pueden llegar a convertirse en nubes. Sin embargo, hemos encontrado que los vapores que se pensaba daban cuenta de toda la formación de aerosoles en la atmósfera inferior sólo pueden explicar una pequeña fracción, incluso con el aumento producido por los rayos cósmicos”.

Los aerosoles atmosféricos juegan un papel importante en el clima: reflejan la luz solar y producen gotas de las nubes. La producción de aerosoles adicionales, por tanto, aclara las nubes y permite extender su vida útil. Según estimaciones actuales, alrededor de la mitad de todas las gotas de las nubes comienzan con la agrupación de moléculas que están presentes en la atmósfera solo en pequeñas cantidades. Algunos de estos grupos de moléculas crecen lo suficiente con el tiempo como para convertirse en las ‘semillas’ de las gotas de las nubes. Asimismo se cree que rastros de ácido sulfúrico y vapores de amoníaco son importantes, por lo que se utilizan en todos los modelos para estudiar la atmósfera, pero el mecanismo y el tipo por el que se agrupan junto con las moléculas de agua son poco conocidos.

Los resultados de CLOUD muestran que a pocos kilómetros en la atmósfera, el ácido sulfúrico y de vapor de agua pueden formar rápidamente grupos de moléculas que dan lugar a nubes, y que los rayos cósmicos favorecen la tasa de formación hasta diez veces o más. Sin embargo, en la capa más baja de la atmósfera, a un kilómetro aproximadamente de la superficie terrestre, los resultados muestran que el proceso de formación de nubes requiere vapores adicionales como los del amoníaco. Sin embargo, los resultados muestran que ácido sulfúrico, agua y amoníaco solo, incluso con la mejora experimentada por los rayos cósmicos, no son suficientes para explicar la formación de aerosoles observada en la atmósfera. Por lo tanto debes participar sustancias adicionales, y descubrir su identidad será el siguiente paso del experimento.

“Fue una gran sorpresa descubrir que la formación de aerosoles en la parte baja de la atmósfera no se debe solo al ácido sulfúrico, agua y amoníaco”, dijo Kirby. “Ahora es de vital importancia descubrir qué sustancias adicionales están involucradas, ya sean naturales o de origen humano, y cómo influyen en las nubes. Esta será nuestra próxima labor”.

El experimento CLOUD consiste en una cámara en la que se pueden simular las condiciones atmosféricas con control y precisión, incluyendo el estudio de las concentraciones de vapores que lleva a la formación de aerosoles. Un haz de partículas procedente del acelerador sincrotrón de protones del CERN proporciona una fuente artificial y ajustable de la radiación cósmica. CLOUD (acrónimo de Cosmics Leaving OUtdoor Droplets) es una colaboración internacional de científicos de Austria, Finlandia, Alemania, Portugal, Rusia, Suiza, Reino Unido y los Estados Unidos.

In a paper published in the journal ‘Nature’, the CLOUD experiment at CERN has reported its first results. The CLOUD experiment has been designed to study the effect of cosmic rays on the formation of atmospheric aerosols – tiny liquid or solid particles suspended in the atmosphere – under controlled laboratory conditions. Atmospheric aerosols are thought to be responsible for a large fraction of the seeds that form cloud droplets. Understanding the process of aerosol formation is therefore important for understanding the climate.

The CLOUD results show that trace vapours assumed until now to account for aerosol formation in the lower atmosphere can explain only a tiny fraction of the observed atmospheric aerosol production. The results also show that ionisation from cosmic rays significantly enhances aerosol formation. Precise measurements such as these are important in achieving a quantitative understanding of cloud formation, and will contribute to a better assessment of the effects of clouds in climate models.

“These new results from CLOUD are important because we’ve made a number of first observations of some very important atmospheric processes,” said the experiment’s spokesperson, Jasper Kirkby. “We’ve found that cosmic rays significantly enhance the formation of aerosol particles in the mid troposphere and above. These aerosols can eventually grow into the seeds for clouds. However, we’ve found that the vapours previously thought to account for all aerosol formation in the lower atmosphere can only account for a small fraction of the observations – even with the enhancement of cosmic rays.”

Atmospheric aerosols play an important role in the climate. Aerosols reflect sunlight and produce cloud droplets. Additional aerosols would therefore brighten clouds and extend their lifetime. By current estimates, about half of all cloud droplets begin with the clustering of molecules that are present in the atmosphere only in minute amounts. Some of these embryonic clusters eventually grow large enough to become the seeds for cloud droplets. Trace sulphuric acid and ammonia vapours are thought to be important, and are used in all atmospheric models, but the mechanism and rate by which they form clusters together with water molecules have remained poorly understood until now.

The CLOUD results show that a few kilometres up in the atmosphere sulphuric acid and water vapour can rapidly form clusters, and that cosmic rays enhance the formation rate by up to ten-fold or more. However, in the lowest layer of the atmosphere, within about a kilometre of Earth’s surface, the CLOUD results show that additional vapours such as ammonia are required. Crucially, however, the CLOUD results show that sulphuric acid, water and ammonia alone – even with the enhancement of cosmic rays – are not sufficient to explain atmospheric observations of aerosol formation. Additional vapours must therefore be involved, and finding out their identity will be the next step for CLOUD.

“It was a big surprise to find that aerosol formation in the lower atmosphere isn’t due to sulphuric acid, water and ammonia alone,” said Kirkby. “Now it’s vitally important to discover which additional vapours are involved, whether they are largely natural or of human origin, and how they influence clouds. This will be our next job.”

The CLOUD experiment consists of a state-of-the-art chamber in which atmospheric conditions can be simulated with high control and precision, including the concentrations of trace vapours that drive aerosol formation. A beam of particles from CERN’s Proton Synchrotron accelerator provides an artificial and adjustable source of cosmic radiation.

http://www.fpa.csic.es

Enlaces:

• Nota de prensa del CERN (inglés/francés)
• Web del experimento CLOUD en el CERN

CERN’s CLOUD experiment provides unprecedented insight into cloud formation

Geneva, 25 August 2011. In a paper published in the journal Nature today, the CLOUD¹ experiment at CERN² has reported its first results. The CLOUD experiment has been designed to study the effect of cosmic rays on the formation of atmospheric aerosols – tiny liquid or solid particles suspended in the atmosphere – under controlled laboratory conditions. Atmospheric aerosols are thought to be responsible for a large fraction of the seeds that form cloud droplets. Understanding the process of aerosol formation is therefore important for understanding the climate.

The CLOUD results show that trace vapours assumed until now to account for aerosol formation in the lower atmosphere can explain only a tiny fraction of the observed atmospheric aerosol production. The results also show that ionisation from cosmic rays significantly enhances aerosol formation. Precise measurements such as these are important in achieving a quantitative understanding of cloud formation, and will contribute to a better assessment of the effects of clouds in climate models…..[+

Supporting information

Download supporting information [PDF]: CLOUD_SI_press-briefing_29JUL11.pdf

Multimedia resources

• Video News Release: http://cdsweb.cern.ch/record/1364842
• CERN News (video): http://cdsweb.cern.ch/record/1370582
• Illustration: http://cdsweb.cern.ch/record/1375156
• Photos of the CLOUD experiment: http://cdsweb.cern.ch/record/1374405, http://cdsweb.cern.ch/record/1221293

Contact

CERN Press Office, press.office@cern.ch
+41 22 767 34 32
+41 22 767 21 41
http://www.cern.ch/Press

Follow CERN at:

• www.cern.ch
• http://twitter.com/cern/

http://press.web.cern.ch/press/PressReleases/Releases2011/PR15.11E.html

1. The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment is conducted by an international and interdisciplinary collaboration of scientists from Austria (University of Innsbruck, University of Vienna), Finland (Finnish Meteorological Institute, Helsinki Institute of Physics, University of Eastern Finland, University of Helsinki), Germany (Johann Wolfgang Goethe University Frankfurt, Leibniz Institute for Tropospheric Research), Portugal (University of Beira Interior, University of Lisbon), Russia (Lebedev Physical Institute), Switzerland (CERN, Paul Scherrer Institut), the United Kingdom (University of Leeds) and the United States of America (California Institute of Technology).

2. CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

Video News Release : CLOUD

CLOUD experiment interview Jasper Kirkby

Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation DOI: 10.1038/nature10343 Jasper Kirkby1, Joachim Curtius,2, João Almeida2,3, Eimear Dunne4, Jonathan Duplissy1,5,6, Sebastian Ehrhart2, Alessandro Franchin5, Stéphanie Gagné5,6, Luisa Ickes2, Andreas Kürten2, Agnieszka Kupc7, Axel Metzger8, Francesco Riccobono9, Linda Rondo2, Siegfried Schobesberger5, Georgios Tsagkogeorgas10, Daniela Wimmer2, Antonio Amorim3, Federico Bianchi9,11, Martin Breitenlechner8, André David1, Josef Dommen9, Andrew Downard12, Mikael Ehn5, Richard C. Flagan12, Stefan Haider1, Armin Hansel8, Daniel Hauser8, Werner Jud8, Heikki Junninen5, Fabian Kreissl2, Alexander Kvashin14, Ari Laaksonen15, Katrianne Lehtipalo5, Jorge Lima3, Edward R. Lovejoy13, Vladimir Makhmutov14, Serge Mathot1, Jyri Mikkilä5, Pierre Minginette1, Sandra Mogo3, Tuomo Nieminen5, Antti Onnela1, Paulo Pereira3, Tuukka Petäjä5, Ralf Schnitzhofer8, John H. Seinfeld12, Mikko Sipilä5,6, Yuri Stozhkov14, Frank Stratmann10, Antonio Tome3, Joonas Vanhanen5, Yrjo Viisanen16, Aron Vrtala7, Paul E. Wagner7, Hansueli Walther9, Ernest Weingartner9, Heike Wex10, Paul M. Winkler7, Kenneth S. Carslaw4, Douglas R. Worsnop5,17, Urs Baltensperger9, and Markku Kulmala5 1CERN, Geneva, Switzerland 2Goethe-University of Frankfurt, Institute for Atmospheric and Environmental Sciences, Frankfurt am Main, Germany 3SIM, University of Lisbon and University of Beira Interior, Lisbon, Portugal 4University of Leeds, School of Earth and Environment, Leeds, United Kingdom 5Department of Physics, University of Helsinki, Finland 6Helsinki Institute of Physics, University of Helsinki, Finland 7University of Vienna, Faculty of Physics, Vienna, Austria 8Ionicon Analytik GmbH and University of Innsbruck, Institute for Ion and Applied Physics, Innsbruck, Austria 9Paul Scherrer Institut, Laboratory of Atmospheric Chemistry, Villigen, Switzerland 10Leibniz Institute for Tropospheric Research, Leipzig, Germany 11University of Milan, Department of Inorganic, Metallorganic, and Analytical Chemistry, Milan, Italy 12California Institute of Technology, Division of Chemistry and Chemical Engineering, Pasadena, USA 13NOAA Earth System Research Laboratory, Boulder, Colorado, USA 14Lebedev Physical Institute, Solar and Cosmic Ray Research Laboratory, Moscow, Russia 15University of Eastern Finland, Kuopio, Finland 16Finnish Meteorological Institute, Helsinki, Finland 17Aerodyne Research Inc., Billerica, Massachusetts, USA The following funding acknowledgements from the authors appear at the end of the paper: This research has received funding from the EC Seventh Framework Programme under grant agreement no. 215072 (Marie Curie Initial Training Network, “CLOUD-ITN”) and ERC-Advanced Grant “ATMNUCLE” no. 227463, the German Federal Ministry of Education and Research (project no. 01LK0902A), the Swiss National Science Foundation, the Academy of Finland Center of Excellence program (project no. 1118615), the Austrian Science Fund (FWF; project no. P19546 and L593), and the Russian Academy of Sciences and Russian Foundation for Basic Research (grant N08-02-91006-CERN).

http://cdsweb.cern.ch/record/1364842

Saturday, August 27th, 2011, by Manuel and is filed under "CERN, Ciencia, Science | , CERN, Ciencia, CLOUD experiment, Science ". Both comments and pings are currently closed.