The absorption and reflection properties of clouds depend on the cloud optical depth (COD), which is partly linked to their liquid water content ( Stephens, 1984 Zhang et al., 1996). The net cloud radiative effect – the balance between these opposite contributions – is notably determined by the surface albedo ( Bintanja and van den Broeke, 1996 Hofer et al., 2017) and cloud properties, i.e their temperature ( Stephens, 1984), structure ( Barrett et al., 2017 Gilbert et al., 2020), and water phase (ice or liquid) ( Lachlan-Cope, 2010 Van Tricht et al., 2016 Hines et al., 2019 Gilbert et al., 2020). They can have opposing effects by reflecting solar (shortwave) radiation towards space and by emitting trapped energy through thermal (longwave) radiation towards the surface. As liquid-containing clouds are projected to increase the melt spread associated with a given warming rate, they could be a major source of uncertainties in projections of the future Antarctic contribution to sea level rise.Ĭlouds are key drivers of the surface energy budget (SEB) of snow and ice. Clouds containing a larger amount of supercooled liquid water lead to stronger melt, subsequently favouring the absorption of solar radiation due to the snowmelt–albedo feedback. Furthermore, we highlight that differences in meltwater production for the same climate warming rate depend on cloud properties and particularly cloud phase. We show that clouds enhance future surface melt by increasing the atmospheric emissivity and longwave radiation towards the surface. Here we use the polar-oriented regional climate model MAR (Modèle Atmosphérique Régional) to study the physical mechanisms that would control future surface melt over the Antarctic ice shelves in high-emission scenarios RCP8.5 and SSP5-8.5. So far it remains unclear whether these differences are due to variations in warming rates in individual models or whether local feedback mechanisms of the surface energy budget could also play a notable role. However, model projections with similar greenhouse gas scenarios suggest large differences in cumulative 21st-century surface melting. Share your favorite shelfies (photos or video of shelf clouds) to our /photos gallery, our Facebook page, or via Twitter MORE PHOTOS: 10 Spectacular Clouds | Earth's Highest Clouds | Hole-Punch Clouds) MORE ON WEATHER.Recent warm atmospheric conditions have damaged the ice shelves of the Antarctic Peninsula through surface melt and hydrofracturing and could potentially initiate future collapse of other Antarctic ice shelves. The National Weather Service in Lubbock, Texas, documented a spectacular case of cold-frontal roll clouds in late September 2007. Either the gust front surged well away from the parent thunderstorm(s), or the thunderstorm(s) may have fizzled, leaving this remnant roll cloud.Īdvancing cold fronts have also triggered roll clouds on occasion. Unlike a shelf cloud, the roll cloud is detached from its parent thunderstorm(s). Wind gusts once the shelf cloud has passed may be quite strong, causing downed trees, tree limbs and power outages. When this warm, moist air condenses, you see the shelf cloud.Īs the shelf cloud passes, you feel an abrupt shift in wind direction and increased wind speed, followed within minutes by heavy rain or hail. Warmer, more moist air is lifted at the leading edge, or gust front, of this rain-cooled air. Rain-chilled air descends in a thunderstorm's downdraft, then spreads laterally when reaching Earth's surface. What you're seeing in a shelf cloud is the boundary between a downdraft and updraft of a thunderstorm or line of thunderstorms. ( PHOTOS: Scary Clouds That Are Not Tornadoes) While menacing in appearance, shelf clouds are not tornadoes or wall clouds. Shelf clouds are typically seen at the leading edge of a thunderstorm or squall line of thunderstorms. To understand how roll clouds form, we first must explain how shelf clouds develop. The first two photos in the slideshow from Lake Hendricks, Minnesota, on June 20, 2015, show a terrific example of a roll cloud. Based on their appearance, we certainly understand why.Ī more rare variety of this type of cloud, a roll cloud, resembles a giant rolling pin in the sky. A shelf cloud, also known as an arcus or arc cloud, may be the most frequently submitted cloud photo to our photo gallery and Facebook page.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |