Slide 1Slide 2Slide 3Slide 4Video: cloud formation in TucsonQuestionsVideoClouds Roles - Importance of CloudsSlide 9Slide 10Slide 11Slide 12Slide 13Slide 15Slide 16Water in the atmosphereCondensationSlide 20Slide 21Slide 22Clouds and radiationClouds and day to day temperaturesWhich day would be warmer?Which evening would be warmer?Slide 27Low and High cloudsClouds and climateChanges in cloudsChanges in cloudsSlide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51MET 112 Global Climate Change -CLOUDS and CLIMATEProf. Menglin Susan JinDepartment of Meteorology, San Jos State UniversityOutlineClouds FormationClouds Climatology Clouds and the Radiation BudgetClouds by Christina RossettiWhite sheep, white sheep,On a blue hill,When the wind stopsYou all stand stillWhen the wind blowsYou walk away slow.White sheep, white sheep,Where do you go?Clouds are formed when air containing water vapor is cooled below a critical temperature called the dew point and the resulting moisture condenses into droplets on microscopic dust particles (condensation nuclei) in the atmosphere. A Scientists’ view of Clouds CLOUDS: A visible mass of liquid water droplets suspended in the atmosphere above Earth's surface. http://earthobservatory.nasa.gov/Library/glossary.php3A good repository of cloud photos in various categories can be foundat www.cloudappreciationsociety.org/gallery5 MET 112 Global Climate ChangeVideo: cloud formation in Tucsonhttp://www.youtube.com/watch?v=NiCSk1zxMEs Timelapse of Tucson cloud formationsQuestionsWhat role do clouds play on the Earth’s climate?What would happen to our climate if clouds were to increase/decrease?How does clouds formation change with pollution?7 MET 112 Global Climate ChangeVideohttp://www.met.sjsu.edu/metr112-videos/MET%20112%20Video%20Library-MP4/clouds/DTS-5.mp4Clouds-1.mp4 –clouds and aerosols8 MET 112 Global Climate ChangeClouds Roles - Importance of CloudsClouds is part of hydrological cycle to move waterClouds is key in energy–Clouds absorb/reflect short wave radiation(clouds alebedo effect)–Clouds emit longwave radiation back to space–clouds absorb surface longwave radiation and keep the heat in the atmosphere to warm the surface(clouds greenhouse effect)Earth System Water Cycle100% of the incoming energy from the sun is balanced by 100% percent total energy outgoing from the earth. incoming energy from the Sun = outgoing energy from the Earth.11 MET 112 Global Climate Changesince the Earth is much cooler than the Sun, its radiating energy is much weaker (long wavelength) infrared energy. energy radiation into the atmosphere as heat, rising from a hot road, creating shimmers on hot sunny days. The earth-atmosphere energy balance is achieved as the energy received from the Sun balances the energy lost by the Earth back into space. So, the Earth maintains a stable average temperature and therefore a stable climate. http://www.srh.noaa.gov/jetstream//atmos/energy.htmClouds are formed when air containing water vapor is cooled below a critical temperature called the dew point and the resulting moisture condenses into droplets on microscopic dust particles (condensation nuclei) in the atmosphere. Clouds FormationCLOUDS: A visible mass of liquid water droplets suspended in the atmosphere above Earth's surface. http://earthobservatory.nasa.gov/Library/glossary.php315 MET 112 Global Climate ChangeWater freely evaporating and condensingSince more water molecules are evaporating than condensing, then net evaporation is occurring.Clouds can form along warm and cold fronts, where air flows up the side of the mountain and cools as it rises higher into the atmosphere, and when warm air blows over a colder surface, such as a cool body of water.Water in the atmosphereDefinitions:–Evaporation:–Condensation:–Precipitation:Process where a liquid changes into a gasAny liquid or solid water that falls from the atmosphere to the ground. (i.e. RAIN!)Process where a gas changes into a liquidCondensationThe process by which water vapor changes to a cloud droplet Water vapor molecules may ‘stick’ to condensation nuclei and grow (billions) to eventually form cloud droplet.Examples of condensation nuclei include:a. Dustb. Saltc. Smoke Condensation occurs primarily as temperature cools:-colder the molecules more likely they are to ‘stick’ to other molecules21 MET 112 Global Climate ChangeAerosols Affect Cloud Droplet SizeCCN1.Aerosols serve as cloud condensation nuclie (CCN)CCN2. More aerosols, they will compete for water vapor to condense on, so smaller cloud dropletOcean caseLand caseZonal Mean Cloud Effective Radius(M. D. King, S. Platnick et al. – NASA GSFC)July 2006 (Collection 5)AquaWhy ocean has larger cloud droplets than land?Clouds and radiationCloud - Climate InteractionsAlbedo effect - COOLINGClouds reflect incoming solar radiation. The cloud droplet size and total water content determine the overall reflectivity. Greenhouse effect - WARMINGClouds are good absorbers (and emitters) of long wave (infrared) radiation.Clouds and day to day temperaturesImagine that you are going camping in the Sierras with your friends. On the first day (and evening) it is clear, while on the second day (and evening) it is cloud. Based on this information alone:Which day would be warmer?Which evening would be warmer?Explain your answers.Which day would be warmer?1. First day (clear)2. Second day (cloudy)3. Both the sameWhich evening would be warmer?1. First day (clear)2. Second day (cloudy)3. Both the sameClouds typesLow and High cloudsConsider two types of clouds:1. Low levels clouds 2. High levels cloudsQ: How is the Earth’s surface energy budget different for low clouds compared to high clouds?Clouds and climateCloud A: Low level, (dark, thick)Cloud B: High level, light (sub visible or thin)Excellent reflector of incoming radiation; good absorber/emitter of infrared radiationFair/poor reflector of incoming radiation; good/excellent absorber/emitter of infrared radiationSo, clouds both warm and cool the earth. Overall, though, clouds act to cool the earthChanges in cloudsIncreases in low level clouds will:– Increases in high level clouds will:Changes in cloudsIncreases in low level clouds will:–cool the surface (cooling outweighs warming)Increases in high level clouds will:–warm the