Outline Ulrike Lohmann and Marc W¨uest(IAC Institut Klima f¨urAtmosph¨areund Ulrike Lohmann and ETH, Oct 26, 2005 Importance Marc W¨uest ETH Z¨urich Thermodynamics, Clouds and Precipitation Atmospheric Physics ETH Cloud types ) Atmospheric Physics e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Importance Cloud types Individual clouds Cloud formation Miscellaneous I Lecturers: Ulrike Lohmann (CHN O11, Tel: 044 633 0514, [email protected]) Marc W¨uest (CHN P18, Tel: 044 633 3781, [email protected]) I Textbook: A Short Course in Cloud Physics, R. R. Rogers and e c n M. K. Yau, Pergamon Press, 1989 e i Sc I Prerequisite: Any introduction to Atmospheric Science e t a m I Objective: Understanding the importance of cloud and i l C d precipitation physics n a c i I Grading Scheme: 3 credit points; marked; 5 assignments r he p I Slides: English in order for you to get familiar with scientific s o tm English terminology A H T I Notes: one day before lecture at: for E tute http : //www.iac.ethz.ch/education/atmospheric physics C ti s A n I I Ulrike Lohmann and Marc W¨uest(IACETH) Atmospheric Physics ETH, Oct 26, 2005 Outline Ulrike Lohmann and Marc W¨uest(IAC Course Outline: first half (Ulrike Lohmann) 7. 6. 5. 4. 3. 2. 1. Dec 7: Formation and growth of ice crystals Nov 30: Formation and growthNov of 23: cloud droplets Aerosols, cloud condensation and ice nuclei Nov 16: Mixing and convection Nov 9: Parcel buoyancy and atmospheric stability Nov 2: Review thermodynamics necessary for clouds Oct 26: Introduction to aerosols and clouds Importance ETH Cloud types ) Atmospheric Physics e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Course Outline: second half (Marc W¨uest) 7. 6. 5. 4. 3. 2. 1. Lohmann) Feb 8: Radiative effects of clouds and aerosols (Ulrike Feb 1: Weather modification Jan 25: Severe storms and hail Jan 18: Precipitation processes Jan 11: Weather radar Dec 21: Rain and snow Dec 14: Initiation of rain in non-freezing clouds Importance ETH Cloud types ) Atmospheric Physics e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Importance of clouds I I I I I I temperature and moisture. determine the vertical redistribution ofUpdrafts trace and species, downdrafts associated withand clouds production largely of secondary species. Clouds provide a medium forthem aqueous-phase to chemical the reactions surface (wetClouds deposition). scavenge gaseous and particulatesurface materials as and rain return or snow Clouds deliver water from theradiation atmosphere emitted to by the the Earth’s Earth’sreflecting surface. sunlight back to spaceClouds and are trapping a infrared major factorof in different the sizes. Earth’s radiationDefinition: budget, Clouds consist of cloud droplets and/or ice crystals Importance ETH Cloud types ) Atmospheric Physics → hydrological cycle e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Global mean energy budget Importance Figure: Kiehl and Trenberth, BAMS, 1997 ETH Cloud types ) Atmospheric Physics e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Motivation Figure: Importance Components of 2xCO ETH Cloud types ) Atmospheric Physics 2 warming, from Ruddiman [2001] e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Mean total cloud amount 1983-2001 Importance Figure: International Cloud Climatology Program ETH Cloud types ) Atmospheric Physics e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Importance Cloud types Individual clouds Cloud formation Geographic distribution of the “cloud forcing” e c n e i Sc e t a m i l C d n a c i r he So p shortwave cloud forcing (SCF) = FSW -FSW ,cs = (αcs − αcld ) ⇒ s I 4 o albedo effect of clouds tm A H T longwave cloud forcing (LCF) = F -F ⇒ greenhouse effect for I LW ,cs LW E tute of clouds C ti s A n I I Ulrike Lohmann and Marc W¨uest(IACETH) Atmospheric Physics ETH, Oct 26, 2005 Figure: Cloud forcings from ERBE, cloud cover from ISCCP Outline Ulrike Lohmann and Marc W¨uest(IAC Geographic distribution of the “cloud forcing” Figure: Importance SCF Global mean values: =-49 W m Cloud forcings from ERBE, cloud cover from ISCCP ETH − Cloud types 2 ) ; Atmospheric Physics LCF =32 W m e c Individual clouds n e i − Sc 2 e t a ; m CF i l C d =-17 W m n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm − A H 2 T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Hydrological cycle Importance Figure: ETH Cloud types ) Quante, J. Phys IV, 2004 Atmospheric Physics e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Mean total precipitation 1979-2001 Importance Figure: Global Precipitation Climatology Project ETH Cloud types ) Atmospheric Physics e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Seasonal variation in total precipitation Importance Figure: ETH Cloud types ) Atmospheric Physics Adler et al., 2003 e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Time series of total precipitation Importance Figure: ETH Cloud types ) Atmospheric Physics Adler et al., 2003 e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC 10 cloud types in 4 families: Cloud types I I I I I I I 1 heights refer to mid latitudes High altitude ice clouds (7-16Mid km): level Ci, clouds Cs, (2-7 Cc km):Low As, base Ac and layered (0-2 km Low base with vertical extent: Cu, Cb, Ns Cirrus (Ci): ice clouds Stratus (St): layered cloud Cumulus (Cu): vertical development Importance ETH Cloud types ) Atmospheric Physics 1 ): St, Sc e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC From: Quante, J. Phys IV, [2004] surface observations Annual average cloud amounts [%] from Cirrus Altocumulus Altostratus Nimbostratus Cumulonimbus Cumulus Stratocumulus Stratus Cloud type Importance ETH Cloud types ) Atmospheric Physics e 22 17 4 5 4 5 12 5 Land c Individual clouds n e i Sc e t a m i l C d n a c i r 13 22 6 4 12 22 11 Ocean he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Importance Cloud types Individual clouds Cloud formation CONVECTIVE CLOUDS Stratosphere strong Tropopause wind ice Troposphere e c n -40 C e i Sc e t a m i l C d n a c i r he Shallow Moderate Cond. Deep Cond. Unst. p s Cond. Unst. layer layer o Cb cloud tm Unst. Cu congestus A H layer cloud T Cu cloud for E Figure: Houze’s cloud atlas: www.atmos.washington.edu/gcg/Atlas/ tute C ti s A n I I Ulrike Lohmann and Marc W¨uest(IACETH) Atmospheric Physics ETH, Oct 26, 2005 Outline Ulrike Lohmann and Marc W¨uest(IAC Schematic of layer clouds Importance Figure: STRATUS (St) STRATOCUMULUS (Sc) ETH St layer broken up Cloud types ) liquid usually Atmospheric Physics <2 km <2 km Houze’s cloud atlas NIMBOSTRATUS (Ns) COLD e c Individual clouds n e i (DEEP) Sc e <2 km t a m i l FOG Steam Fog C Like St d n Cold a c i Water r he Fog p ETH, Oct 26, 2005 s o Cloud formation tm St A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Schematic of mid-level clouds Importance Figure: ETH Cloud types ) Atmospheric Physics MIDDLE CLOUDS (bases 2 - 7 km A.G.) Houze’s cloud atlas ALTOSTRATUS (As) ALTOCUMULUS (Ac) SUN e c Individual clouds n Liquid and e i Ice (usually) Sc corona e t 2-7 2-7 a m km ° i 15 km l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC Schematic of cirrus clouds Importance Figure: ETH Cloud types ) Atmospheric Physics Houze’sCIRROSTRATUS cloud atlas (Cs) CIRROCUMULUS SUN (Like Ac) (ICE) e c ICE Individual clouds n e "halo" i > 6 km Sc e ° t 22 a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC bands, rounded masses Altocumulus castellanus (Houze): gray or white broken sheets, elements, Importance ETH Cloud types ) Atmospheric Physics e c Individual clouds n e i Sc e t a m i l C d n a c i r he p ETH, Oct 26, 2005 s o Cloud formation tm A H T for E tute C ti s A n I I Outline Ulrike Lohmann and Marc W¨uest(IAC very low, gray, uniform layer (sunStratus outline (Karlsruher very Wolkenatlas: distinct when visible) Importance ETH Cloud types ) Atmospheric Physics http : // e c www Individual clouds n e i Sc .