Clouds and PrecipitationClouds and PrecipitationPressure and WindStability of AtmosphereStability of Atmosphere• Air rises due to a number of factors• Expands as it rises: cools as it does so–Can calculate the new temperatureCan calculate the new temperature – Use the adiabatic lapse rate: •Dry for unsaturated•Dry for unsaturated• Wet for saturated–Compare the temperature of the air that has–Compare the temperature of the air that has risen to the temperature of the air at that height–Use the environmental lapse rate–Use the environmental lapse rate• Higher density air that has risen is stable (cooler)•Lower density air that has risen is unstable (warmer)Lower density air that has risen is unstable (warmer)Stable conditionsStable conditionsStabilityStability• Environmental lapse rate¾5°C/1000 m• Dry adiabatic lapse rate¾10°C/1000¾10°C/1000 m• Rising air is cooler than area it rises intog• Stable!!Absolute instabilityAbsolute instabilityStabilityStability• Environmental lapse rate¾12°C/1000 m• Dry adiabatic lapse rate¾10°C/1000¾10°C/1000 m• Rising air becomes warmer than area it grises into•Unstable!!•Unstable!!• More unstable upon reaching dew point!Conditional stabilityConditional stabilitySurface inversionSurface inversion• Note the environmental temperature is cool at the surface, increases for some distance, then decreases at greater heightInversion aloftInversion aloft•These inversions are stable because theThese inversions are stable because the warmer air is buoyant over colder surfaceLA Basin InversionLA Basin InversionInversion LayerLos AngelesInversion Layer—Los AngelesCloud DevelopmentCloud Development• Air cools upon rising•Cools to dew–point temperatureCools to dewpoint temperature• Condensation begins• “Lifting condensation level”Cloud ShapesCloud Shapes• Cirrus—curl (of hair): thin wisps•Stratus—blanket: extensive layersStratusblanket: extensive layers• Cumulus—pile: puffy massesAdditional modifier of name• Nimbus = rain¾Cumulonimbus: puffy rain clouds¾Cumulonimbus: puffy rain clouds¾Nimbostratus : layered rain cloudsCloud GroupsCloud Groups• High clouds—6000 m or more above surface•Middle clouds—2000 m to 6000 m aboveMiddle clouds2000 m to 6000 m above• Low clouds—less than 2000 m above surface• Clouds of vertical development–Present through more than one levelPresent through more than one level– Product of atmospheric instabilitycirruscirrusCirrocumulusCirrocumulusCirrostratusCirrostratusAltocumulusAltocumulusAltostratusAltostratusNimbostratusNimbostratusCumulusCumulusCumulonimbusCumulonimbusCloud classificationleftCloud classification—leftCloud classificationrightCloud classification—rightFogGolden Gate BridgeFog—Golden Gate BridgeFogTule FogFog—Tule FogCondensation in cloudsCondensation in cloudsBergeron notesBergeron notesBergeron Process of ice-crystal growthCollision coalescenceGlaze iceGlaze iceGiant hailstoneGiant hailstoneHail damageHail damageRime iceRime icePogonipPogoniphttp://grannysatticquilts.com/pogonip.htmlPrecipitation measurementPrecipitation measurementPrecipitation Map of Washingtonhttp://www.ptguide.com/weather/index.htmlPrecipitation Map of WashingtonWeather radar displayWeather radar displayWindfarm in CaliforniaWindfarm in CaliforniaHurricane at Corpus ChristiHurricane at Corpus ChristiMercury BarometerMercury BarometerAneroid BarometerAneroid BarometerAneroid BarographAneroid BarographIsobarsIsobarsNo Coriolis EffectNo Coriolis EffectCoriolis EffectCoriolis EffectGeostrophic WindsGeostrophic Winds500 millibar altitude chart500 millibar altitude chartRidge and trough of 500 mbRidge and trough of 500 mbUpper level windUpper level windSurface WindSurface WindCyclonic and anticyclonic windsCyclonic and anticyclonic windsCyclonic circulation—northern hemisphereCyclonic winds—southern hemisphereVertical Airflow around cyclonic/anticyclonic
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