Protons for Breakfast Global Warming Week 4 In the event of…In the event of an attack of mutant...
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Transcript of Protons for Breakfast Global Warming Week 4 In the event of…In the event of an attack of mutant...
- Slide 1
- Slide 2
- Protons for Breakfast Global Warming Week 4
- Slide 3
- In the event ofIn the event of an attack of mutant bananas In the event of
- Slide 4
- Global Warming Can we collect your facts please
- Slide 5
- What do we mean by Climate? What is the Climate? Its the average weather in a particular area What is the Climate? Its the average weather Over a period a time (30 years usually) Averages of temperatures and rain occurrence Calculated scientifically Things like that determine what we call the Climate Determine what the climate of a place will be.
- Slide 6
- One problem Do you have any personal evidence that the global climate is changing?
- Slide 7
- This Evening 1.Why is the Earths surface the temperature it is? 2.The Earths Atmosphere 3.Increasing Carbon Dioxide 4.Should we be concerned? 5.Whats going to happen? 6.What should we do?
- Slide 8
- Energy Balance
- Slide 9
- How hot does an object get when placed in front of a fire?
- Slide 10
- Light from the Sun heats the Earth The Sun Earth 5400 C
- Slide 11
- Light from the Sun heats the Earth Drawn to Scale The Sun Earth (drawn 100 times too big) (drawn to scale)
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- Light from the Sun heats the Earth The Earth then radiates heat away Light from the Sun Earth
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- Energy Balance heat input from the Sun heat lost from the Earth by radiation When there is balance, the Earths average temperature will be stable Earth Warms Earth Cools
- Slide 14
- The Energy Balance of the Earth
- Slide 15
- Earth Warms Earth Cools Energy Balance: to scale World Energy Production heat input from the Sun heat lost from the Earth
- Slide 16
- Some more details
- Slide 17
- How much light reaches the Earth? Earth At the top of the atmosphere Above the Equator At midday About 1360 W/m 2
- Slide 18
- How much light reaches the Earth? Earth North Pole South Pole Equator 1360 W/m 2 680 Whole Earth Average 340 W/m 2
- Slide 19
- How much light reaches the Earths Surface Light reflected from Earth Average Value 100 watts per square metre Light from the Sun Average Value 340 watts per square metre
- Slide 20
- Hold on a moment! What about all the heat rising up from the Earths hot centre?
- Slide 21
- Earth 6400 km radius 5500 C Heat flow is less than 0.1 Watt per square metre Temperature increases by ~20 C for each kilometre below the Earths surface Heat flow to and from surface from the Sun 240 Watt per Square metre
- Slide 22
- A remarkable fact Heat flow from the centre of the Earth can be completely ignored when considering what determines the surface temperature of the Earth!
- Slide 23
- What determines the surface temperature of the Earth? Infra Red Radiation cools the Earth Light from the Sun heats the Earth
- Slide 24
- Radiation Balance Light from the Sun heats the Earth Average Value 240 watts per square metre Average Value 240 watts per square metre
- Slide 25
- Radiation Balance How hot must the Earth be to radiate 240 W/m 2 ? Average Value 240 watts per square metre -18 C
- Slide 26
- A Question What is the average temperature of the Earth? 1 metre above the surface and averaged over: day and night, all latitudes and longitudes. all seasons (a) 15 C (b) 5 C (c) + 5 C (d) + 15 C
- Slide 27
- Summary -18 C Average Surface Temperature 33 C Temperature for radiation balance +15 C Greenhouse Effect
- Slide 28
- The Earths surface is 33 C warmer than it would be if had no atmosphere
- Slide 29
- This Evening 1.Why is the Earths surface the temperature it is? 2.The Earths Atmosphere 3.Increasing Carbon Dioxide 4.Should we be concerned? 5.Whats going to happen? 6.What should we do?
- Slide 30
- The composition of the atmosphere? Gas% Nitrogen (N 2 )78.1 Oxygen (O 2 )20.1 Argon (Ar)0.93 Water (H 2 O)0.1 to 1 Carbon Dioxide (CO 2 )0.035
- Slide 31
- Illustration of atmospheric composition About 100 molecules O2O2 Ar N2N2
- Slide 32
- Illustration of atmospheric composition About 1200 molecules Water(H 2 O)
- Slide 33
- Illustration of atmospheric composition About 10000 molecules Carbon dioxide (CO 2 )
- Slide 34
- Nitrogen (N 2 ), Oxygen (O 2 ) & Argon (Ar) Suppose the atmosphere contained no carbon dioxide or water N 2, O 2 and Ar is more than 99% of the atmosphere Molecules have one or two atoms Natural frequency of vibration in the ultra-violet Make atmosphere opaque to ultra-violet light Transparent to infra-red and visible radiation
- Slide 35
- Nitrogen (N 2 ), Oxygen (O 2 ) & Argon (Ar) With an atmosphere of only Nitrogen Oxygen & Argon, what would be the surface temperature? Average Value 240 watts per square metre Average Value 240 watts per square metre -18 C
- Slide 36
- Greenhouse warming is caused by Water (H 2 O) Carbon Dioxide (CO 2 )
- Slide 37
- What is special about H 2 O and CO 2 Molecules have three atoms Natural frequencies of vibration in the infra-red They make the atmosphere opaque to certain infra- red frequencies
- Slide 38
- Vibrations of CO 2 and H 2 0 Different types of molecular jiggling occur at different frequencies Water H 2 0 Carbon dioxide C0 2
- Slide 39
- Absorption demo Frequency
- Slide 40
- The Transparency of the Atmosphere
- Slide 41
- Warning! Complicated diagram !
- Slide 42
- Infra RedUltra VioletVisible Absorption bands
- Slide 43
- Infra Red Radiation cools the Earth
- Slide 44
- Radiation Balance in the 20 th Century On Average 240 W/m 2 On Average 390 W/m 2 150 W/m 2 sent back to Earth Average Value 240 W/m 2 On Average + 15 C
- Slide 45
- Greenhouse Warming 33 C Others