{"id":25508,"date":"2024-12-05T23:35:29","date_gmt":"2024-12-05T17:50:29","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=25508"},"modified":"2024-12-05T23:40:28","modified_gmt":"2024-12-05T17:55:28","slug":"cloud-experiment-resolves-puzzle-of-new-aerosol-particles-in-upper-troposphere","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/cloud-experiment-resolves-puzzle-of-new-aerosol-particles-in-upper-troposphere\/","title":{"rendered":"CLOUD experiment resolves puzzle of new aerosol particles in upper troposphere"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

Geneva– In a\u00a0paper<\/a>\u00a0published today in the journal\u00a0Nature<\/em>, the\u00a0CLOUD collaboration<\/a>\u00a0at CERN reveals a new source of atmospheric aerosol particles that could help scientists refine climate models.<\/p>\n\n\n\n

Aerosols are microscopic particles suspended in the atmosphere that arise from both natural sources and human activities. They play an important role in Earth\u2019s climate system because they seed clouds and influence their reflectivity\u00a0and coverage. <\/p>\n\n\n\n

Most\u00a0aerosols\u00a0arise from the spontaneous condensation of molecules that are present in the atmosphere only in minute concentrations. However, the vapours responsible for their formation are not\u00a0well understood, particularly in the remote upper troposphere.<\/p>\n\n\n\n

The CLOUD (Cosmics Leaving Outdoor Droplets) experiment at CERN is designed to investigate the formation and growth of atmospheric aerosol particles in a controlled laboratory environment. CLOUD comprises a 26\u00a0m3<\/sup>\u00a0ultra-clean chamber and a suite of advanced instruments that continuously analyse its contents. The chamber contains a precisely selected mixture of gases under atmospheric conditions, into which beams of charged pions are fired from CERN\u2019s proton synchrotron to mimic the influence of galactic cosmic rays.<\/p>\n\n\n\n

\u201cHigh concentrations of aerosol particles have been observed\u00a0high\u00a0over the Amazon rainforest for the past twenty years, but their source has remained a puzzle until now,\u201d says CLOUD spokesperson Jasper Kirkby. <\/p>\n\n\n\n

\u201cOur latest study shows that the source is isoprene emitted by the rainforest and lofted in deep convective clouds to high altitudes, where it is oxidized to form highly condensable vapours.\u00a0Isoprene represents a vast source of biogenic particles in both the present-day and pre-industrial atmospheres that is currently missing in atmospheric chemistry and climate models.\u201d<\/p>\n\n\n\n

Isoprene is a hydrocarbon containing five carbon atoms and eight hydrogen atoms. It is\u00a0emitted by broad-leaved trees and other vegetation and is the most abundant non-methane hydrocarbon released into the atmosphere. Until now, isoprene\u2019s ability to form new particles has been considered negligible.<\/p>\n\n\n\n

The\u00a0CLOUD results change this picture. By studying the reaction of hydroxyl radicals with isoprene at upper tropospheric temperatures of \u221230 \u00b0C and \u221250 \u00b0C, the collaboration discovered that isoprene oxidation products form copious particles at ambient isoprene concentrations.\u00a0 This new source of aerosol particles does not require any additional vapours. <\/p>\n\n\n\n

However, when minute concentrations of sulphuric acid or iodine oxoacids were introduced into the CLOUD chamber, a 100-fold increase in the aerosol formation rate was observed. Although sulphuric acid derives mainly from anthropogenic\u00a0sulphur dioxide emissions, the acid concentrations used in CLOUD can also arise from natural sources.

In addition, the team found that isoprene oxidation products drive rapid growth of\u00a0particles to sizes at which they can seed clouds and influence the climate\u2014a behavior that persists in the presence of nitrogen oxides produced by lightning at upper-tropospheric concentrations. After continued growth and descent to lower altitudes, these particles may provide a globally\u00a0important source for seeding shallow continental and marine clouds, which influence Earth\u2019s radiative balance (the amount of incoming solar radiation compared to outgoing longwave radiation).<\/p>\n\n\n\n

\u201cThis new source of biogenic particles in the upper troposphere may impact estimates of Earth’s climate sensitivity, since it implies that more aerosol particles were produced in the pristine pre-industrial atmosphere than previously thought,\u201d adds Kirkby. \u201cHowever, until our findings have been evaluated in global climate models, it\u2019s not possible to quantify the effect.\u201d<\/p>\n\n\n\n

The CLOUD findings are consistent with aircraft observations over the Amazon, as reported in an\u00a0accompanying paper\u00a0<\/a>in the same issue of\u00a0Nature<\/em>. Together, the two papers provide a compelling picture\u00a0of the importance of isoprene-driven aerosol formation and its relevance to the atmosphere.<\/p>\n\n\n\n

Since it began operation in 2009, the CLOUD experiment has unearthed several mechanisms by which aerosol particles form and grow in different regions of Earth\u2019s atmosphere.<\/p>\n\n\n\n

\u201cIn addition to helping climate researchers understand the critical role of aerosols in Earth\u2019s climate, the new CLOUD result demonstrates the rich diversity of CERN\u2019s scientific program and the power of accelerator-based science to address societal challenges,\u201d says CERN Director for Research and Computing, Joachim Mnich.<\/p>\n","protected":false},"excerpt":{"rendered":"

In a\u00a0paper\u00a0published today in the journal\u00a0Nature, the\u00a0CLOUD collaboration\u00a0at CERN reveals a new source of atmospheric aerosol particles that could help scientists refine climate models.<\/p>\n","protected":false},"author":2,"featured_media":25509,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,15],"tags":[],"class_list":["post-25508","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research","category-environment"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest.jpg",1100,619,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-200x200.jpg",200,200,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-675x380.jpg",675,380,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-768x432.jpg",750,422,true],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-675x380.jpg",675,380,true],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest.jpg",1100,619,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest.jpg",1100,619,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest.jpg",1100,619,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-870x570.jpg",870,570,true],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-600x619.jpg",600,619,true],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-600x600.jpg",600,600,true],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-760x490.jpg",760,490,true],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-550x360.jpg",550,360,true],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest-95x65.jpg",95,65,true],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest.jpg",640,360,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest.jpg",96,54,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/12\/Isoprene-from-forest.jpg",150,84,false]},"author_info":{"info":["RevoScience"]},"category_info":"Research<\/a> Environment<\/a>","tag_info":"Environment","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/25508","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=25508"}],"version-history":[{"count":5,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/25508\/revisions"}],"predecessor-version":[{"id":25515,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/25508\/revisions\/25515"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/25509"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=25508"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=25508"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=25508"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}