[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/mt\/article\/modal\/7331\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n      \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n      1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n      2) Linking back to our original story\u003Cbr \/\u003E\n      3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n      \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n      \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n        \n\u003Cdiv\u003E\n  \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003ECloud shapes and formations impact global warming \u2013 but we still don\u2019t understand them\u003C\/h2\u003E\u003Cp\u003EClouds are one of the biggest question marks in global climate models, and a wild card in predicting what will happen to the climate as temperatures rise. They play a vital role in how much of the sun\u2019s radiation makes it into and gets trapped in our atmosphere. The more clouds there are, the more radiation bounces off their tops and is reflected back into space; it also means that if there are more clouds, the radiation reflected by Earth gets trapped. Historically researchers have struggled to understand cloud properties, how they currently behave, and how they will react to the increased temperatures caused by climate change.\u003C\/p\u003E\u003Cp\u003EIt comes down to an issue of scale, explains Dr Bony. From the microscopic interactions of atoms to atmospheric currents that act over thousands of kilometres, many forces affect how clouds form, their composition and behaviour.\u003C\/p\u003E\u003Cp\u003EThe clouds resembling cotton wool in the Atlantic, which Dr Bony and her colleagues study, are a good example. \u2018A little change in their properties has a huge impact on the global radiative balance (the balance between how much of the sun\u2019s energy makes it into Earth\u2019s atmosphere and how much escapes),\u2019 she said. Because these fair-weather clouds (known as \u003Ca href=\u0022https:\/\/www.eoas.ubc.ca\/courses\/atsc113\/flying\/met_concepts\/01-met_concepts\/01a-clouds\/cumuliform.html#:~:text=Convective%20clouds%20or%20cumuliform%20clouds,warm%20air%20drives%20strong%20updrafts.\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Ecumuliform clouds\u003C\/a\u003E) are so common, a small change carries \u2018huge\u2019 statistical weight in the global climate.\u003C\/p\u003E\u003Cp\u003E\u0027It\u2019s the biggest question \u2013 there is no bigger question,\u2019 said Professor Bjorn Stevens, a director of the Max Planck Institute for Meteorology in Germany and Dr Bony\u2019s co-leader on the\u0026nbsp;\u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/694768\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EEUREC4A\u003C\/a\u003E\u0026nbsp;project which set out to investigate these fluffy white clouds. \u2018For 50 years, people have been making climate projections, but all of them have had a false representation of clouds.\u0027\u0026nbsp;These projections, he says, have suffered from an\u0026nbsp;inadequate understanding of\u0026nbsp;the\u0026nbsp;factors\u0026nbsp;determining\u0026nbsp;how\u0026nbsp;cloudy climate will be and have not been properly represented in the models.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EField experiment\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe EUREC4A project, which began as a modest field experiment to measure air motion and cloudiness, attracted numerous partners and expanded in scope. In the end, it encompassed five\u0026nbsp;crewed and six\u0026nbsp;remotely piloted research aircraft, four\u0026nbsp;ocean-going research vessels, a flotilla of drifters and gliders, an array of satellites, and measurements from the\u0026nbsp;\u003Ca href=\u0022https:\/\/journals.ametsoc.org\/bams\/article\/97\/5\/787\/69884\/The-Barbados-Cloud-Observatory-Anchoring\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EBarbados Cloud Observatory\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003E\u2018The experiment grew in complexity and scope to address a number of other fascinating questions,\u2019 said Prof. Stevens, such as how much and how easily clouds rain, and how eddies in the ocean and the clouds above affect each other. The team is currently writing up their results, and hopes that\u0026nbsp;their measurements will provide the answers to these questions. \u2018We will be setting a ground truth for a new set of climate models,\u2019 he said.\u003C\/p\u003E\u003Cp\u003EFor Dr Bony, the next step extends beyond understanding cloud properties and the area they cover.\u003C\/p\u003E\u003Cp\u003E\u2018Now, we\u2019re discovering that it\u2019s not only the total area, but also the way that clouds are distributed and organised,\u2019 she said. The patterns that they form could also influence how they block or absorb radiation, and this information could have implications for the role of clouds in climate change.\u003C\/p\u003E\u003Cp\u003EDr Jan H\u00e4rter, an atmospheric complexity specialist at the Leibniz Centre for Tropical Marine Research, the Jacobs University Bremen, Germany and the \u003Ca href=\u0022https:\/\/www.nbi.ku.dk\/english\/research\/biocomplexity\/atmospheric_complexity\/pictures\/billeder\/people\/\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003ENiels Bohr Institute in Denmark\u003C\/a\u003E, is investigating this question in his \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/771859\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EINTERACTION\u003C\/a\u003E project. \u2018Many types of clouds show features of organisation, but thunderstorm clouds (in the tropics) show self-organisation,\u2019 he said. INTERACTION looks at how thunderstorms cluster, using simulation as well as developing basic models for their behaviour.\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022text-center text-blue font-bold text-2xl w-full lg:w-1\/2 border-2 border-blue p-12 my-8 lg:m-12 lg:-ml-16 float-left\u0022\u003E\n  \u003Cspan class=\u0022text-5xl rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n  \u003Cp class=\u0022font-serif italic\u0022\u003E\u2018For 50 years, people have been making climate projections, but all of them have had a false representation of clouds.\u2019\u003C\/p\u003E\n  \u003Cfooter\u003E\n    \u003Ccite class=\u0022not-italic font-normal text-sm text-black\u0022\u003EProf. Bjorn Stevens, Max Planck Institute for Meteorology, Germany \u003C\/cite\u003E\n  \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ESelf-organisation\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EClouds can organise for many reasons, such as when they are above an urban area which tends to be hotter than the countryside because of all the concrete and asphalt. Self-organisation occurs when clouds form and cluster even though the conditions below and the sunlight above them are uniform.\u003C\/p\u003E\u003Cp\u003EThunderstorm clouds, known as \u003Ca href=\u0022https:\/\/cloudatlas.wmo.int\/en\/cumulonimbus-cb.html\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Ecumulonimbus\u003C\/a\u003E (which comes from the Latin \u003Cem\u003Ecumulus\u003C\/em\u003E \u2018heaped\u2019 and \u003Cem\u003Enimbus\u003C\/em\u003E \u2018rainstorm\u2019), are tall vertical clouds that often bring rain. These clouds are the dominant type of cloud in the tropics and are also key to understanding the global radiative balance.\u0026nbsp; \u2018They are at the latitude where most of the heat comes to Earth, and the sun\u2019s radiation is much stronger there,\u2019 said Dr H\u00e4rter. These tower-like clouds affect how much sunlight enters the atmosphere, which has direct implications for warming.\u003C\/p\u003E\u003Cp\u003E\u2018The question is how much do these tall clouds change in clustering when, for example, temperature changes,\u2019 he said. However, like most issues involving clouds, this is a difficult question to answer.\u003C\/p\u003E\u003Cp\u003EINTERACTION is approaching the matter from two different perspectives: one is to run simulations, which require a large amount of computing time, and another is to develop \u2018toy\u2019 models that explain fundamental thunderstorm-cloud interactions.\u003C\/p\u003E\u003Cp\u003E\u2018Toy\u2019 models are very basic simulations that speak to the fundamental interactions between thunderstorm clouds. For example, Dr H\u00e4rter and his colleagues are trying to understand how these clouds \u2018speak\u2019 to each other and self-organise by breaking down these complex physical interactions into their basic components.\u003C\/p\u003E\u003Cp\u003EWhen there is a thunderstorm, most of the rain falls to the ground but some of it evaporates in the air under the cloud. This air, having incorporated the chilly moisture, becomes a \u2018cold pool\u2019, H\u00e4rter explains. \u2018This evaporation is crucial in communicating signals from one cloud to another.\u2019\u003C\/p\u003E\u003Cp\u003EIf there are hundreds and thousands of clouds in a large area, the cold pools underneath them bump into each other, pushing air up into the colder parts of the atmosphere and seeding new thunderstorm clouds.\u003C\/p\u003E\u003Cp\u003EOne of their \u2018toy\u2019 models portrays how these cold pools interact and this cycle \u2013 of cold pools colliding and generating new clouds \u2013 can last for generations (one lasts about six hours) of clouds, encoding the memories of past clouds and storms into the present topical cloud. The cold pools can continue to influence cloud generation for weeks.\u003C\/p\u003E\u003Cp\u003EThese very basic models are necessary, says Dr H\u00e4rter, in order to remove some of the unknowns for simulating cloud behaviour, such as how these cold pools interact. The team\u2019s simulations already incorporate parameters such as wind speed, humidity, temperature, and cloud composition, which is the different ratios of water, ice, and an icy mixture called graupel.\u003C\/p\u003E\u003Cp\u003EEchoing EUREC4A\u2019s Dr Bony and Prof. Stevens, Dr H\u00e4rter said: \u2018We don\u2019t know how clouds work, especially these thunderstorm clouds that take place at scales that are hard or impossible to resolve with the current climate models.\u2019\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ESimulation\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003ETo take the sheer scale of cloud and their driving forces into consideration, an accurate simulation would have to include disparate variables from the motion of atoms and the energy they dissipate (nanometres) through to the Earth\u2019s rotation and global winds on the scale of about 10,000km. \u2018The very best we can do for, say, a week of simulations is to resolve (the 100-metre scale) for an area of one kilometre by one kilometre, or so,\u2019 he said. \u2018And that is a big simulation.\u2019\u003C\/p\u003E\u003Cp\u003EThe ultimate goal of the project is to have a model for cloud organisation that captures the interactions between past and present thunderstorm clouds, and feed this information into the next generation of climate models. The next step is to begin a field work and feed new measurements into their models.\u003C\/p\u003E\u003Cp\u003E\u2018We need to have a clearer understanding of the different cloud-system feedbacks to make a strong statement on climate change here,\u2019 Dr H\u00e4rter said. \u2018The models have different ways of representing tall clouds and low clouds, and that is something that cannot be resolved without closer observational data.\u2019\u003C\/p\u003E\u003Cp\u003EAnd in order to prepare for a warming climate, and predict how the world\u2019s insulating cloud layer will change, first we need to understand how it operates now.\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the European Research Council. 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