Atmospheric TU Delft Stephan de Roode, Harm Jonker clouds, climate and weather air quality in the urban environmentenergy

Conservation equations Mass Momentum "Navier Stokes" Water Heat

Clouds & Climate Landsat satellite 65 km 10 km Large Eddy Model ~mm~100m ~1  m-100  m Earth ~13000 km

Cloud dynamics 10 m100 m1 km10 km100 km1000 km10000 km turbulence  Cumulus clouds Cumulonimbus clouds Mesoscale Convective systems Extratropical Cyclones Planetary waves Large Eddy Simulation (LES) Model Limited Area Weather Model (LAM) Numerical Weather Prediction (NWP) Model Global Climate Model The Zoo of Atmospheric Models DNS mm Cloud microphysics Fundamental Engineering

Cloud dynamics 10 m100 m1 km10 km100 km1000 km10000 km turbulence  Cumulus clouds Cumulonimbus clouds Mesoscale Convective systems Extratropical Cyclones Planetary waves Large Eddy Simulation (LES) Model Current developments DNS mm Cloud microphysics Limited Area Weather Model (LAM) Global Climate Model Numerical Weather Prediction (NWP) Model Fundamental Engineering

Cloud dynamics 10 m100 m1 km10 km100 km1000 km10000 km turbulence  Cumulus clouds Cumulonimbus clouds Mesoscale Convective systems Extratropical Cyclones Planetary waves Large Eddy Simulation (LES) Model The Zoo of Atmospheric Models DNS mm Cloud microphysics Limited Area Weather Model (LAM) Global Climate Model Numerical Weather Prediction (NWP) Model Harm Jonker Stephan de Roode Pier Siebesma (KNMI/TUD)

Computing the weather

Wien’s law: Stefan-Boltzmann Planck:

Solar radiation UV image of the sun source: SOHO EIT The sun Surface temperature T sun = 5778 K Radius R sun = ×10 5 km Total energy production: Q =  T sun 4 x 4  R sun 2 = 3.85×10 26 W energy emitted (W/m 2 ) total surface area (m 2 )

Solar constant S 0 : flux of solar energy at the top of the Earth's atmosphere Distance R E-S = 1.496×10 11 m Energy conservation: Flux integrated over the imaginairy surface area of a sphere centered around the sun is constant => Q =  T sun 4 x 4  R sun 2 = S 0 x 4  R E-S 2

Radiative equilibrium for an Earth without an atmosphere Radiative equilibrium temperature  p = Earth surface albedo Fraction of solar radiation absorbed by the Earth = Radiation emitted by the Earth

Radiative Earth equilibrium temperature (no atmosphere) sea land ice snow mean albedo Earth real mean T earth = 288 K

Scattering and absorption absorption cross section  a : effective area of the molecule for removing energy from the incident beam shortwave longwave scattering cross section  sca absorption cross section  a

Apply energy balance Energy conservation of the system

Apply energy balance Energy conservation of the system Radiative energy balance of the atmosphere

Apply energy balance Energy conservation of the system Radiative energy balance of the atmosphere Radiative equilibrium temperature of the Earth surface

Radiative equilibrium temperature for an Earth with an atmosphere mean emissivity atmosphere 16°C enhanced greenhouse effect

Stephens et al., 2012

Clouds in a future climate Dufresne & Bony, Journal of Climate 2008 Radiative effects only Water vapor feedback Surface albedo feedback Cloud feedback

The playground for cloud physicists: Hadley circulation deep convectionshallow cumulusstratocumulus

Study the evolution of a low cloud deck during its advection towards the tropics deep convectionshallow cumulusstratocumulus

Study the effects of clouds on the radiation budget with a high- resolution turbulence model

Clouds are strong reflectors of solar radiation cloud layer geometric thickness [m] A total amount of about 0.1 mm of liquid water in an atmospheric column is sufficient to reflect 50% of the downward solar radiation courtesy Kees Floor stratocumulus

The Eddington (E) Index Arthur Eddington (Einstein and Eddington, HBO-BBC co-production, 2008 ) Chandrasekhar (Nobel prize for physics 1983) (E-Index 84!)

Navier Stokes in DWDD

Journal papers writing a paper, how to deal with citations, co-authors? H-index peer review journal impact factor open access journals

Exercises 22 October: Paper discussions Stephens et al., 2012: An update on Earth's energy balance in light of the latest global observations, Nature Geosciences. (group 1 presents, group 2 asks questions) Stevens and Bony, 2013: Water in the atmosphere, Physics Today. (group 3 presents, group 4 asks questions) 29 October?: One paper, one exercise Dufresne and Bony, 2008: An assessment of the primary sources of spread of global warming estimates from coupled atmosphere-ocean models, J. Climate. (group 2 presents, group 1 asks questions) Exercise on equilibrium state solutions of low clouds. (group 3 presents, group 4 asks questions)