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En-en adult card 10 aerosols: Difference between revisions
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== Definitions == | == Definitions == | ||
Aerosols are solid or liquid particles suspended in the air, generally ranging in size from a few nanometres to 10 micrometres and which remain in the atmosphere for at least several hours. Aerosols can be of natural or human origin (through [[En-en adult card 4 transportation|transportation]] or [[En-en adult card 2 industry|industry]]). | Aerosols are solid or liquid particles suspended in the air, generally ranging in size from a few nanometres to 10 micrometres and which remain in the atmosphere for at least several hours. Aerosols can be of natural or human origin (through [[En-en adult card 4 transportation|transportation]] or [[En-en adult card 2 industry|industry]]). They can affect the climate in a variety of ways: [[En-en adult card 15 radiative forcing|directly]], by scattering or absorbing radiation, and [[En-en adult card 15 radiative forcing|indirectly]] by acting as condensation nuclei of clouds or glaciogenic cores, by modifying the optical properties and lifetime of clouds. | ||
== To go further == | |||
=== Origin of anthropogenic aerosols === | |||
Aerosols are a local pollution caused by the incomplete combustion of hydrocarbons. When we burn fossil fuels, a perfect and complete combustion produces only CO2 and water vapour. However, the hydrocarbons we burn are not pure and the combustion is not complete. Therefore, polluting gases such as NOx or carbon monoxide and aerosols such as black carbon (soot) or hydrogen sulphide are also emitted. | |||
=== Natural Aerosols === | |||
If clouds already existed before the industrial era, it is because aerosols exist in their natural state. They are for example microscopic grains of sand, salt crystals, volatile organic compounds (VOCs) such as microorganisms blown by the wind from the leaves of trees. The micro-droplets of water that make up clouds can only form on a condensation core such as an aerosol. | |||
=== Uncertainty related to the calculation of the influence of aerosols === | |||
Although aerosols are thought to cool the climate on average, their total contribution is the result of warming and cooling effects with great uncertainty. The sum of the two is therefore highly subject to uncertainty. The Futura Science article [https://www.futura-sciences.com/planete/dossiers/climatologie-tant-incertitudes-previsions-climatiques-638/ Why so many uncertainties in climate predictions?] (in French) provides a good understanding of the origin of these uncertainties. | |||
=== Other possible links === | |||
==== Causes ==== | |||
[[En-en adult card 3 building|Building usage]] Buildings emit few aerosols directly. The only significant emissions are chimney fires. In Chamonix, 85% of the fine particles present in the atmosphere come from wood heating<ref>[https://www.lemonde.fr/pollution/article/2016/12/08/dans-la-vallee-de-chamonix-le-chauffage-au-bois-est-le-principal-coupable-de-la-pollution_5045636_1652666.html In the Chamonix valley, wood heating is the main culprit of pollution (French).]</ref>. | |||
==== Consequences ==== | |||
[[En-en adult card 38 human health|Human health]] Although aerosols are not alone in the "fine particle" category, every year 391 000 people in EU countries die from air pollution<ref>[https://www.eea.europa.eu/fr/highlights/la-pollution-atmospherique-reste-trop Air pollution remains too high throughout Europe (French)]</ref>, and it causes 1.1 million premature deaths in India and China<ref>[https://www.sciencesetavenir.fr/nature-environnement/l-inde-rattrape-la-chine-en-nombre-de-morts-de-la-pollution_110560 India catches up with China in the number of deaths from pollution (French)]</ref>. | |||
== References == | |||
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