Quant à la formation des nuages, elle n'est guère expliquée. Job xxxvii Par contre, nous entendons ici ou là parler de la provenance des nuages. 1 Rois xviii. La glace est présente dans de nombreux types de nuages et joue un rôle clef dans la formation des précipitations. Malgré leur importance en. La formation des nuages. Directed by: Marie-Hélène Turcotte. Genres: Animation.


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Ice is present in many clouds and is known to play a central role in precipitation formation. Despite the important role in climate, processes associated with clouds represent some of the largest uncertainties in climate models Boucher et al.

Pollen, chimie et nuages - Quoi de neuf - CMOS Bulletin SCMO

To better represent clouds in climate models, our fundamental understanding of the underlying processes controlling their formation and evolution need to be la formation des nuages. Challenges span from the need to investigate microphysical processes, occurring on the molecular scale, to the macro structure of clouds, driven by radiation and dynamics.

Findings from experimental research in the field or laboratory need to be developed into a quantitative format for la formation des nuages in complex climate models. With clouds having a significant impact on the climate and water resources, their representation in climate models requires well developed parametrizations of the experimental and modelling studies.

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  • Orage de masse d'air

With respect to the specific microphysics of ice-forming processes in the atmosphere, more studies on the pathways on the components involved la formation des nuages impacting the ice forming stage are needed. With my research I contribute to a better la formation des nuages of the microscale processes of ice formation under cloud conditions and specifically focus on biological materials in the atmosphere and their ability to facilitate ice nucleation.

In the following brief article, I will give an insight to my ice nucleation research on pollen particles.

Météorologie de la montagne

To date, the specifics of INP surfaces which make ice nucleation a highly selective process are not fully understood. La formation des nuages INP concentrations in the atmosphere being extremely low — only 1 in particles in the atmosphere serves as an INP Rogers et al.

Particles from various sources — including deserts, oceans and urban areas — get emitted into the atmosphere in large quantities. When experiencing cloud conditions with low temperatures and high relative humidity, some of the la formation des nuages have properties which facilitate ice nucleation.

Pollen, chimie et nuages

These particles are referred to as ice nucleating particles INPs and impact cloud la formation des nuages, radiative forcing and precipitation formation. Better understanding of INPs and their role in cloud processes requires a comprehensive investigation of INP processing pathways possible in the atmosphere.

Pollen INPs From the variety of INPs, biological particles have received much attention in recent years after la formation des nuages estimated amounts of primary biological aerosol particles PBAPs emitted into the atmosphere were increased substantially Jaenicke but remain poorly quantified.

Given their organic composition, such biological INPs may experience chemical processing in the atmosphere.


In particular, their surfaces consist of numerous chemical functional groups which are highly susceptible to chemical reaction, especially oxidation via common atmospheric oxidants such as ozone and the hydroxyl la formation des nuages OH.

These effects of atmospheric oxidants on biological INPs are unexplored. In my study, I focused on pollen INPs, which are emitted into the atmosphere in large numbers during vegetation blooming seasons, and investigated their IN ability when exposed to the hydroxyl radical in simulated cloud water Gute and Abbatt Pollen comprise significant amounts of water extractable compounds which are also referred to as subpollen particles SPP on their surface and inside the la formation des nuages.

The SPPs are of submicron sizes, which compared to the relatively large pollen grains few tens of micrometers can be easily suspended and transported by atmospheric winds. These small particles are believed to be polysaccharides and have been shown to be active as La formation des nuages.

Image taken by Ilya Gourevich, University of Toronto.

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Based on this knowledge and motivated la formation des nuages the very small number of prior studies, which investigated the effect of ozone on organic and biological INPs, I investigated OH oxidation in simulated cloud water and its effect on the INP activity of pollen SPP.

Silver birch Betula pendula and grey alder Alnus incana pollen were suspended in water and only the water extractable compounds, which contain the SPP, were used for oxidation experiments. More details of the full experimental procedure are available in Gute and Abbatt In this initial study, I found the IN activity for both birch and alder pollen to significantly la formation des nuages upon OH oxidation.