SJSU METR 112 - CLOUDS and CLIMATE (48 pages)

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CLOUDS and CLIMATE



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CLOUDS and CLIMATE

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Pages:
48
School:
San Jose State University
Course:
Metr 112 - Global Climate Changes
Unformatted text preview:

MET 112 Global Climate Change CLOUDS and CLIMATE Prof Menglin Susan Jin Department of Meteorology San Jos State University Outline Clouds Formation Clouds Climatology Clouds and the Radiation Budget Clouds by Christina Rossetti White sheep white sheep On a blue hill When the wind stops You all stand still When the wind blows You walk away slow White sheep white sheep Where do you go A Scientists view of Clouds 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 CLOUDS A visible mass of liquid water droplets suspended in the atmosphere above Earth s surface http earthobservatory nasa gov Library glossary php3 A good repository of cloud photos in various categories can be found at www cloudappreciationsociety org gallery Video cloud formation in Tucson http www youtube com watch v NiCSk1zxME s Timelapse of Tucson cloud formations MET 112 Global Climate Change 5 Questions 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 Video http www met sjsu edu metr112 videos MET 20112 20Video 20Library MP4 clouds DTS 5 mp4 Clouds 1 mp4 clouds and aerosols MET 112 Global Climate Change 7 Clouds 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 MET 112 Global Climate Change 8 Earth System Water Cycle 100 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 since 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 11 MET 112 Global Climate http www srh noaa gov jetstream atmos energy htm Change Clouds Formation 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 CLOUDS A visible mass of liquid water droplets suspended in the atmosphere above Earth s surface http earthobservatory nasa gov Library glossary php3 Water freely evaporating and condensing Since more water molecules are evaporating than condensing then net evaporation is occurring MET 112 Global Climate Change 15 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 Process where a liquid changes into a gas Condensation Process where a gas changes into a liquid Precipitation Any liquid or solid water that falls from the atmosphere to the ground i e RAIN Condensation 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 Dust b Salt c Smoke Condensation occurs primarily as temperature cools colder the molecules more likely they are to stick to other molecules Aerosols Affect Cloud Droplet Size 1 Aerosols serve as cloud condensation nuclie CCN Ocean case CCN Land case CCN 2 More aerosols they will compete for water vapor to condense on so smaller cloud droplet MET 112 Global Climate Change 21 Zonal Mean Cloud Effective Radius Why ocean has larger cloud droplets than land M D King S Platnick et al NASA GSFC July 2006 Collection 5 Aqua Clouds and radiation Cloud Climate Interactions Albedo 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 temperatures Imagine 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 same Which evening would be warmer 1 First day clear 2 Second day cloudy 3 Both the same Clouds types Low and High clouds Consider two types of clouds 1 Low levels clouds 2 High levels clouds Q How is the Earth s surface energy budget different for low clouds compared to high clouds Clouds and climate Cloud A Low level dark thick Excellent reflector of incoming radiation good absorber emitter of infrared radiation Cloud B High level light sub visible or thin Fair 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 earth Changes 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 surface warming outweighs cooling Cirrus Altocumulus possibly cirrocumulus depending on altitude of the clouds Stratocumulus Broken stratocumulus Nimbostratus Cumulus humilis commonly called fair weather cumulus Cumulus Cumulus Cumulus Cumulus Cumulonimbus Stratus Stratus Cirrus Clouds That Look Like Things Explain how the earth s climate would change as a result of aircraft contrails Class Participation Concept Map Activity Water Concept Map Draw a concept map using the following terms You may add additional terms if you wish Water vapor Ice Liquid water Condensation Evaporation Gas High Cloud Low Cloud Precipitation Condensation nuclei Temperature Warming Cooling Air


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