SIT ANYWHERE TODAY: Topic #10 The Global Energy Balance & 2 Sustainability Segments! Tuesday Oct 19 ANNOUNCEMENTS • RQ-5 REMINDER: Cutoff is this THURSDAY Oct 21st, 30-minutes before class begins. • ASSIGNMENT I-3 is due IN CLASS a week from TODAY (Oct 26th) . The directions are posted in D2L. Please bring your WORKSHEET to class ALREADY STAPLED! (the Written Part of the assignment should be deposited in the Dropbox) • REMEMBER TO CHECK THE WEEKLY D2L CHECKLIST for what to do each week. NOTE: We’ll be reading more in the Dire Predictions text in upcoming
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SIT ANYWHERE TODAY: Topic #10 The Global Energy
Balance & 2 Sustainability Segments!
Tuesday Oct 19
ANNOUNCEMENTS
• RQ-5 REMINDER: Cutoff is this THURSDAY Oct 21st, 30-minutes before class begins.
• ASSIGNMENT I-3 is due IN CLASS a week from TODAY (Oct 26th) . The directions are posted in D2L. Please bring your WORKSHEET to class ALREADY STAPLED! (the Written Part of the assignment should be deposited in the Dropbox)
• REMEMBER TO CHECK THE WEEKLY D2L CHECKLIST for what to do each week. NOTE: We’ll be reading more in the Dire Predictions text in upcoming weeks.
• The EXAMS are being graded this week. You should have them back early next week.
CLICKER UPDATE:
- If get >50% of answers correct, get credit for being here today
GOAL: Enhanced Understanding Of Global Change Science, How It Operates, & What It Means To Me Personally
The Science of Global Change
How science is done
How it linksto my life
“Hands on”assignments
Sustainability
Segments
Physical Science foundation
(matter& energy, electromagnetism,thermodynamics, laws of motion)
Q3: What will happen to incoming SW over the Amazon Rain Forest if parts of it are deforested?
1 = more SW will be absorbed
2 = less SW will be absorbed
Before After
“CARTOON” SYMBOLS:
To represent TERRESTRIAL (longwave IR) radiation emitted upward by the Earth’s surface or the atmosphere
Return to p 122
“CARTOON” SYMBOLS:
To represent TERRESTRIAL (longwave IR) re-radiation emitted downward by the Earth’s ATMOSPHERE
p 122
PUTTING IT TOGETHER:
RNET =
+ - - +
RNET= (Q + q ) - a - Lu + Ld
Can you place + and – signs where they ought to go in the equation?
p 123
Now we’ll look at the energy pathways in a bit more detail by combining the cartoon symbols in various ways . . .
See top p 49
First, what if . . .
. . . The Earth didn’t have an atmosphere, and therefore didn’t have a greenhouse effect??
What would the energy pathways in the Earth-Sun system look like?
Which terms are not involved?
No scattering by atmosphere
No re-radiation of infrared by GHG’s
p 123
To describe the real Earth-Atmosphere system, more detail is needed in our simple representation . . . . . We’ll use our symbols to build an energy balance “model”
SW BEAMED DIRECTLY TO EARTH’SSURFACE WHERE IT IS ABSORBED:
p 123
Incoming SW
SW REFLECTED BACK TO SPACE:
By clouds
By Earth’s surface
p 123
This is determined by the ALBEDO of the clouds or surface
SW SCATTERED BACK TO SPACE BY ATMOSPHERE:
p 123
SW SCATTERED DOWN TO EARTH’s SURFACE where it is absorbed
p 123
SW ABSORBED IN ATMOSPHERE
BY GASES, DUST, etc.
(including Ozone absorbing shortwave
UV)
p 123
Incoming UV SW
absorbed by O3, O2
Incoming Visible SW
absorbed by dust, O3, O2
SW ABSORBED In ATMOSPHERE BY CLOUDS & H2O vapor:
p 124
(NOTE: clouds are made up of tiny droplets of water surrounded by lots of water vapor)
Absorption curve for water vapor
Incoming Visible & Near IR SW absorbed by water vapor
& clouds
LW (IR) EMITTED FROM EARTH’S
SURFACE ESCAPING TO
SPACE THROUGH THE “OUTGOING IR
ATMOSPHERIC WINDOW”
p 124
Outgoing LW
IR EMITTED FROM EARTH’S SURFACE BUT ABSORBED IN THE ATMOSPHERE BY GREENHOUSE GASES (H2O,CO2,
CH4, ETC.)
p 124
IR EMITTED FROM
ATMOSPHERE ESCAPING TO
SPACE
p 124
IR EMITTED FROM
ATMOSPHERE AND RADIATED
BACK TO SURFACE
WHERE IT IS ABSORBED
p 124
All together now:
Can you sketch all the pathways in yourself? p 124
Compare with simpler model of energy balance with NO atmosphere:
p 125
Which terms are not involved?
NOTE: Technically, the SUN does give off incoming longwave infrared radiation (in addition to shortwave UV, visible, etc.) – but if we view the incoming LW symbol above as TERRESTRIAL radiation that has been absorbed and RE-RADIATED BACK TO EARTH by the GHG’s in the atmosphere, this simplification is correct.
If some energy is “left over,” it can be used to DRIVE WEATHER &
CLIMATE through HEAT TRANSFER processes or it can STORED by the
Earth (in the ground or ocean).
The RIGHT side of the ENERGY BALANCE
EQUATION . . .
FINAL PART OF TOPIC #10:
Left side of equation
Right side of equation
R net = “net” left over energy can be used to DRIVE WEATHER & CLIMATE through HEAT TRANSFER processes or it can STORED by the Earth (in the ground or ocean).
p 50 top
Review of: THERMODYNAMICS & HEAT TRANSFER
Conduction = passage of thermal energy through a body without large‑scale movement of matter within the body. Most effective in SOLIDS.
Convection = passage of thermal energy through a fluid (liquid or gas) by means of large‑scale movements of material within the fluid, as in a convection cell. Most effective in GASES & LIQUIDS.
Radiation = the transfer of thermal energy by electromagnetic radiation. The only one of the three mechanisms of heat transfer that does not require atoms or molecules to facilitate the transfer process, i.e., does not even need MATTER as a medium to transfer energy! p 51
of p 61
CONDUCTIONJiggling molecule jiggling molecule
transfer of heat (kinetic energy at molecular scale)
CONVECTION
Mass of warm air or liquid heats, expands, rises
RADIATIONPhoton /wave transport:
even through a void!
review
H = SENSED (via thermometer) ENERGY
(LE released, hence it can be sensed as H)
LE = LATENT (hidden) ENERGY(LE stored)
HEAT TRANSFER & STORAGE DURING PHASE CHANGES: LE & H
Review p 51
Link to the Left Side of Equation:
Radiation = the transfer of heat by electromagnetic radiation.
It doesn’t need MATTER to transfer energy! (sun earth, earth atmosphere, atmosphere earth, earth space)
Link to the Right Side of Equation:
p 51
Conduction & convection plus energy stored & released during phase changes (latent energy => sensible heat, etc.)
Back to p 50
G
SHORTWAVE & LONGWAVE ENERGY FLOW & BUDGET:
Encore: Energy Balance Animation
showing energy flow pathways & “units” of energy that eventually balance out:
9. leads to distinct shadows, while diffuse SW radiation does not
10. All visible wavelengths scattered & transmitted in a colored spectrum by raindrops
11. Attempt to increase absorption & reduce into eyes; reduces glare
12. More is absorbed, leads to more which can then warm up car
13. Hot air (less dense than surrounding cool air) rises in a convection current & lifts balloon
H
14. Wet mud evaporates from pig & cools him: Heat from pig’s body is conducted into soil:
LEG
LE H
15. June is dryer, hence air can hold more water vapor, more evaporation occurs, hence more energy goes into instead of
The RIGHT Side of the Equation:
BE SURE TO REVIEW THE CLASS FOLLOW-UP IF YOU WANT TO GO OVER THESE
ANSWERS AGAIN . . . . .
See you on Thursday
Don’t forget RQ-5!
SOME APPLICATIONS OF THE ENERGY BALANCE IN DIFFERENT
PARTS OF THE GLOBE:
http://www.earthweek.com/
GLOBAL CHANGE in the News!
Warmer-than-average conditions dominated the world’s land areas. The most prominent warmth was in western Alaska, most of the contiguous United States, eastern Canada, Greenland, the Middle East, eastern and central Europe, western and far eastern Russia and northeastern Asia. Cooler-than-average regions included much of Australia, western Canada, parts of the northern United States, parts of western and central Europe, and central Russia.
This year also marked the 14th consecutive September with below-average Arctic sea ice extent.
Antarctic sea ice reached its annual maximum in September. September 2010 was the third largest sea ice extent on record (2.3 percent above average), behind 2006 (largest) and 2007 (second largest).
This summer marks the fourth consecutive year--and fourth time in recorded history--that the fabled passage has opened for navigation. Over the past four days, warm temperatures and southerly winds over Siberia have also led to intermittent opening of the Northeast Passage, the shipping route along the north coast of Russia through the Arctic Ocean. It is now possible to completely circumnavigate the Arctic Ocean in ice-free waters, and this will probably be the case for at least a month. This year marks the third consecutive year--and the third time in recorded history--that both the Northwest Passage and Northeast Passage have melted free, according to the National Snow and Ice Data Center. The Northeast Passage opened for the first time in recorded history in 2005, and the Northwest Passage in 2007. It now appears that the opening of one or both of these northern passages is the new norm, and business interests are taking note--commercial shipping in the Arctic is on the increase, and there is increasing interest in oil drilling. The great polar explorers of past centuries would be astounded at how the Arctic has changed in the 21st century.