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Greenhouse Effect: the details

Detailed energy balanceGreenhouse Gases

Introduction

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Wavelength (micron)

I n t e n s i t y

( A . I U . )

1 2

10

5

0

288 K

5 15

x 2,000,000

Short wavelength in, long out

Black Body Curve: Planck’s Law

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Main ideas • Visible (short) wavelength radiation is

absorbed by the Earth’s surface

• The surface of the Earth heats up

• The Earth re-radiates mostly at infrared (long) wavelengths

• The infrared radiation is absorbed by themolecules in the Earth’s atmosphere

• The Earth’s atmosphere heats up, re-radiates upwards AND downwards

•

The Earth’s surface heats up ….

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77

168

67

390

30

324

390

30

Reected solar Radiation 107 Wm -2

Incident solar radiation 342 Wm -2

Radiated infrared radiation 235 Wm -2

Reected by clouds & gasesin atmosphere

Surface reection

Absorbed bySurface Thermals

Evapotranspiration SurfaceEmission Absorbed by Surface

radiated back towardsEarth

324 Wm -2

Absorbed byAtmosphere

Emitted by

Atmosphere Greenhouse

Gases

78 24

Warning! Youratmosphere is

absorbing some ofthe incoming solar

radiation

1,370 W/m2 at 12 noon Average 342 W/m 2 over 24 hours

Gives the average temperature of +15 oC

205

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Colder 6oC per km

Absorb heat lowin the warmatmosphere

Radiate heathigh in the coldatmosphere

Warm airrises and

cools

High absorption

E* = Twarm4 Wm -2

Low radiation

E* = Tcold4 Wm -2

The Greenhouse Effect

H e

i g h t

( k m

)

5

10

–50 0

Temperature ( oC)

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The Greenhouse gases

Ar

Tri-atomic or greater Bi-atomic or lesser

H2O

CO 2

CH 4

N2 , O 2 NO 2

Moon seen through the atmosphere, Credit: NASA; Molecular models, Credit: after Wikipedia

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Svante Arrhenius (1859-1927)

“On the influence of Carbonic Acid in the Air Uponthe Temperature of the Ground”

Phil Mag 41 237-76 (1896)

Conclusion: Double CO 2 = Temperature rise of5-6 oC

(Predicted would take 3,000 years)

h t t p : / / e n . w

i k i p e

d i a

. o r g

/ w i k i / S v a n

t e_

A r r h e n

i u s

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Greenhouse Effect: the details

• Detailed energy balance• Tri-atomic gases absorb infrared

radiation• Svante Arrhenius: first to

understand the role of CO 2 inheating Earth’s atmosphere

Summary

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Slide Details

2 Swirling Maelstrom ( http://sdo.gsfc.nasa.gov/assets/gallery/preview/Swirling_304_Sept2010.jpg ) by NASA [Public Domain]Full Earth (http://www.nasa.gov/images/content/115334main_image_feature_329_ys_full.jpg ) by NASA/Apollo 17 [Public Domain]Black body curves of Planck ( https://en.wikipedia.org/wiki/File:Black_body.svg) by Darth Kule (Own Work) [Public Domain], via WikimediaCommons

4 (partial) Swirling Maelstrom ( http://sdo.gsfc.nasa.gov/assets/gallery/preview/Swirling_304_Sept2010.jpg ) by NASA [Public Domain]#View of the crescent moon through the top of the earth's atmosphere ( http://commons.wikimedia.org/wiki/File:Top_of_Atmosphere.jpg )By NASA Earth Observatory [Public domain], via Wikimedia Commons#Greenhouse Diagram by David Jamieson based on concepts expressed in (Houghton J) Global Warming. #Cambridge University Press(2009).Panorama Hueckeswagen-Pleuse ( http://www.ickr.com/photos/lestidae/5436828569/ ) by Andre Schaefer (CC BY-SA 2.0)

5 View of the crescent moon through the top of the earth's atmosphere ( http://commons.wikimedia.org/wiki/File:Top_of_Atmosphere.jpg ) ByNASA Earth Observatory [Public domain], via Wikimedia Commons#Distribution of temperature diagram by David Jamieson

6 View of the crescent moon through the top of the earth's atmosphere ( http://commons.wikimedia.org/wiki/File:Top_of_Atmosphere.jpg ) ByNASA Earth Observatory [Public domain], via Wikimedia Commons#Carbon-dioxide-3D-vdW ( http://commons.wikimedia.org/wiki/File:Carbon-dioxide-3D-vdW.svg ) By Jacek FH (Own work based onImage:Carbon-dioxide-3D-vdW.png), (CC-BY-SA-3.0), via Wikimedia Commons Nitrogen-dioxide-3D-vdW ( http://commons.wikimedia.org/wiki/File:Nitrogen-dioxide-3D-vdW.png ) By Benjah-bmm27 (Own work) [PublicDomain], via Wikimedia Commons Nitrogen-3D-vdW ( https://en.m.wikipedia.org/wiki/File:Nitrogen-3D-vdW.png ) By Benjah-bmm27 (Own work) [Public Domain], viaWikimedia Commons Water molecule 3D By Dbc334( http://commons.wikimedia.org/wiki/File:Water_molecule_3D.svg ) (rst version); Jynto (second version)

(File:Water-3D-vdW.png ) [Public domain], via Wikimedia Commons Methane-3D-space-lling ( http://en.wikipedia.org/wiki/File:Methane-3D-space-lling.svg) (rst version); Jynto (second version)(File:Water-3D-vdW.png ) [Public domain], via Wikimedia Commons Ar by David Jamieson

7 vante Arrhenius ( http://commons.wikimedia.org/wiki/File:Arrhenius2.jpg ) by Author Unknown [Public Domain], via Wikimedia Commons

Image Credits