Sit with your Group for G-3 Topic #11 Systems & Feedbacks

Thursday Oct 21st

ANNOUNCEMENTS

• RQ-5 was due today 30 minutes before class begins. RQ-6 is due NEXT Thursday – will be posted Friday.

• ASSIGNMENT I-3 is due IN CLASS next Tuesday. The directions are posted in D2L. Please bring your worksheet to class ALREADY STAPLED!

• The EXAMS are being graded this week. You should have them back early next week.

G-3 ASSIGNMENT (5 pts)

Applying the Energy Balance Terms

Your task is to decide which component or components working together are most directly related to or responsible for the observed phenomenon.

p 53

# 13 - #15: Right side of equation

# 1 – #12 : Left side of equation

1. blue skies

2. Sunglasses while skiing

3. Bright even though cloudy

4. More intense solar radiation (tan /skin damage, etc.)

at noon vs. dawn or dusk

Solar rays perpendicular to body

Solar rays perpendicular to body

NOON

DAWN or DUSK

Sun just above

horizon

Sun directly

overhead

5. The Greenhouse Effect

A B C

EARTH

SUN

EARTH

SUN

EARTH

SUN

B is better than the others . . . But only the circled part represents the GH

Effect!! . . .

To illustrate the GREENHOUSE EFFECT:

Greenhouse effect

6. Red sunsets

7. Infrared cameras / “night vision”

8. “Tennis whites” tradition

9. Shadow on sunny day

10. Rainbow

11. Black streaks

12. Parking on blacktop

13. Hot air balloon

14. Pigs cooling off in the mud

15. Evaporative coolers work best in the desert

TIME TO WRAP UP FOR TODAY!

G-3 ASSIGNMENT (5 pts) (cont.)

Applying the Energy Balance Terms

Don’t forget to SIGN IN with the #’s you wrote up!

THE ANSWERS

2. 3.

4. Noon: more dusk: more

1. gases of atmosphere scatter shorter blue wavelengths

5. + together = the Greenhouse Effect

The LEFT side of the equation:

6. (dust, thicker atmosphere scatters longer red/orange wavelengths)

7. radiates day & night; camera senses IR

8.

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:

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).

http://psc.apl.washington.edu/ArcticSeaiceVolume/IceVolume.php

http://nsidc.org/data/seaice_index/index.html

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.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1589

http://nsidc.org/seaice/characteristics/difference.html

Antarctic vs Arctic . . .

http://climateprogress.org/2010/08/28/arctic-sea-ice-volume-northwest-passage-david-barber-antarctic-sea-ice/

TOPIC # 11

Introduction to Models:

UNDERSTANDING SYSTEMS

&FEEDBACKS

Class notes pp 55-61

“When one tugs at a single thing in nature,

one finds it attached to the rest of the world.”

~ John Muir

p 73

SYMBOLIC NOTATION

• use of a picture or diagraminstead of words

• abbreviation, symbol, or acronym instead of spelling out

the whole word or concept:

NATS 101-GC

$ % & + - = x or *

IPCCp 55

SYMBOLIC NOTATION (cont)

NUMBERS!!

1, 2, 8 3.8 x 10 - 4

Elements and molecules:

H, He, H2O CO2

Formulas & Equations

y = a + bx (equation for a straight line) p 55

SYMBOLIC NOTATION (cont)MODELS!

WHAT IS A MODEL?

• a representation of something (usually miniature or not to scale)

• an example for imitation or emulation

• a person or thing that serves as a pattern

• an analogy or analogue of something

p 55

WHAT IS A MODEL?

• "a description or analogy to help visualize something that cannot be directly observed"

• or "a system of postulates, data, and inferences presented as a mathematical description of an entity or state of affairs"

Note the word “system”

p 55

WHAT IS A SYSTEM?

• SYSTEM = a set of interacting components

• SYSTEM MODEL =

a set of assumptions, rules, data and inferences that define the interactions among the components of a system and the significant interactions between the system and the “universe” outside the system

p 55

SYSTEM DIAGRAM =

A diagram of a system that uses graphic symbols or icons to represent components in a depiction of how the system works

p 55

One example of a system diagram for a model used in global change

studies:

Another more complicated system diagram:

Component (def) =

An individual part of a system. A component may be a reservoir of matter or energy, a system attribute, or a subsystem.

COMPONENT

p 55

Coupling (def):

The links between any two components of a system.

Couplings can be positive (+) or negative (-)

COUPLING

p 55

A coupling between an electric blanket temperature component and a body

temperature component:

If the electric blanket’s temperature INCREASES . . .

The person’s body temperature will also INCREASE

+

Q1: What type of COUPLING IS THIS?

1) Positive + 2) Negative - p 55

A coupling between a person’s body temperature and an electric blanket’s

temperature

If the person’s body temperature INCREASES and he gets too hot . . .

The electric blanket’s temperature control will be turned down and the blanket temperature will DECREASE

-

Q2: What type of COUPLING IS THIS?

1) Positive + 2) Negative - p 55

THE “RULE” – how to tell if it’s a positive or negative coupling:

Positive couplings have a solid “arrow” with a normal arrowhead pointing in the direction of the

coupling:

Negative couplings have an “open circle” arrowhead pointing in the direction of the coupling:

Feedback mechanism (def):

a sequence of interactions in which the final

interaction influences the original one.

Feedbacks occur in loops

FEEDBACKS

p 56

Feedback Loop (def) =

A linkage of two or more system components that forms a ROUND-TRIP flow of information.

Feedback loops can be positive (+) or negative (-).

p 56

A positive feedback is an interaction that amplifies the response of the system in which it is incorporated

(self-enhancing; amplifying).

p 56

A negative feedback is an interaction that reduces or dampens the response of the system in which it is incorporated

(self-regulating; diminishes the effect of perturbations))

p 56

One way to remember the effect that a NEGATIVE feedback loop has is to think of the word "negligible"

i.e., a perturbation or disturbance in a system characterized by a negative feedback loop will be able to adjust to the perturbation and ultimately the effect on the system will be negligible

FEEDBACK LOOP

Q3: What kind of FEEDBACK LOOP IS IT?

1) Positive (+) 2) Negative (-) ???

-

p 56

THE “RULE” – how to tell if it’s a positive or negative feedback LOOP:

Count the # of number of NEGATIVE COUPLINGS:

If there is an ODD # of negative Couplings, the loop is NEGATIVE:

If there is an EVEN # of negative couplings, the loop is POSITIVE

One more term:

EQUILIBRIUM STATE

= a state in which a system is in equilibrium

stated another way:

= the state in which the system will remain unless something disturbs it.)

An equilibrium state can be: stable or unstable.

Take notes

The presence of FEEDBACK LOOPS leads to the establishment of EQUILIBRIUM STATES:

• Negative feedback loops establish STABLE equilibrium states

NEGATIVE LOOP STABLE EQUILIBRIUM

[recall negative feedback = “self regulating”]

STABLE EQUILIBRIUM STATES:

• are resistant to a range of perturbations

(i.e., system responds to modest perturbations by returning to the stable equilibrium state) Take notes

A negative feedback loop (can also be described as)

a STABLE EQUILIBRIUM STATE :

Take notesSee top

figure on p 59

A modest disturbance (short-term

perturbation)

response that tends to return

the system to its equilibrium state

p 59

A LARGE or more persistent disturbance (a forcing) can carry the system to a different equilibrium state

(so there area some limits to stability, even in a stable state!)

Proper alignment of dual control

electric blanket:

p 56

Everyday life example:

Improper alignment:Q4. What kind of FEEDBACK LOOP IS IT?

1) Positive + 2) Negative -

+

A POSITIVE FEEDBACK LOOP that amplifies the effect! p 56

A positive feedback loop can also be described as an UNSTABLE

EQUILIBRIUM STATE :

the slightest disturbance from a comfortable state may lead to system adjustments that

carry the system further and further from that state.

p 59

RECAP:The presence of FEEDBACK LOOPS leads to the establishment of EQUILIBRIUM STATES

• Negative feedback loops establish STABLE equilibrium states that are resistant to a range of perturbations; the system responds to modest perturbations by returning to the stable equilibrium state

• Positive feedback loops establish UNSTABLE equilibrium states. A system that is poised in such a state will remain there indefinitely. However, the slightest disturbance carries the system to a new state.

p 59

LINKING TO GLOBAL CHANGE:

In Global Change science we are concerned about disturbances that both humans and natural factors can produce in the Earth system:

(e.g. increasing carbon dioxide)

. . . and whether or not the Earth can adjust to these and have a stable equilibrium state, or be thrown into an unstable state due to positive feedback loops

WATER VAPOR Feedback in the Earth-Atmosphere Q5: What kind of FEEDBACK LOOP IS

THIS?

1) Positive + 2) Negative -

p 56

POSITIVE FEEDBACK LOOP that amplifies the effect!

p 56

OUTGOING INFRARED ENERGY FLUX /

TEMPERATURE FeedbackQ6: What kind of FEEDBACK LOOP IS

THIS?

1) Positive + 2) Negative -

p 56

NEGATIVE FEEDBACK LOOP that is self-regulating!

p 56

Ok, so what’s this Daisyworld Climate System all about and why should I care??????

SNOW AND ICE ALBEDO Feedback

Q7: What kind of FEEDBACK LOOP IS THIS?

1) Positive + 2) Negative -

p 56

ALSO a POSITIVE FEEDBACK LOOP that amplifies the effect!

p 56ALBEDO REVIEW

If a surface’s albedo is LOW absorption by the surface is HIGH => HOTTER surface!

If a surface’s albedo is HIGH, absorption by the surface is LOW COOLER surface

YIKES!

Review

PLANET EARTH = ~ 0.30

“Planetary albedo”

Review

Positive & Self-Amplifying Feedback Loop!

p 56

PLANET EARTH = ~ 0.30

CLOUDS: 0.44 (high, thin) - 0.90 (low, thick) Review

An increase in daisy coverage a decrease in surface

temperature

WHY? because more sunlight is reflected back (albedo increases) less sunlight is absorbed cooler temps

-

HOW DAISY COVERAGE AFFECTS TEMPERATURE:

tem

pera

ture

Daisy coverage

- p 57

HOW TEMPERATURE AFFECTS DAISY COVERAGE:

Coupling is positive Coupling is negativeAs temp

increases daisy coverage increases

As temp increases daisy coverage decreases

-+

temperature

Dais

y c

overa

ge

p 57

tem

pera

ture

Daisy coverage

temperature

Dais

y c

overa

ge

temperature

Dais

y c

overa

ge “flipped axes”

PUTTING THE TWO GRAPHS TOGETHER!

P1

P2

p 57

P1 and P2 are:

EQUILIBRIUM STATES

= a state in which a system is in equilibrium, that is, the state in which the system will remain UNLESS something disturbs it.

An equilibrium state can be stable or unstable.

p 59

P1 & P2 are each “EQUILIBRIUM” states, but one is in a more

precarious state (unstable) than the

other . . . .p 59

RECAP/ SUMMARYThe presence of FEEDBACK LOOPS leads to the establishment of EQUILIBRIUM STATES

• Negative feedback loops establish STABLE equilibrium states that are resistant to a range of perturbations; the system responds to modest perturbations by returning to the stable equilibrium state

• Positive feedback loops establish UNSTABLE equilibrium states. A system that is poised in such a state will remain there indefinitely. However, the slightest disturbance carries the system to a new state.

The last part of Chapter 2 illustrates that:

FEEDBACK FACTORS that are negative provide a “buffer” from FORCINGS – they allow the daisies to survive LONGER after a climate change (e.g., an increase in solar luminosity) than they could have survived if NO feedback processes were in operation.

We will learn that this is EXACTLY what is happening on EARTH under many circumstances.

What we are worried about are the circumstances when feedback factors that are POSITIVE under a climatic FORCING.

ZOMBIE BREAK !

HBODocumentary

FIlm( 2006 )

SUSTAINABILITY SEGMENT FILM (cont.)

As you watch the segments of this film . . . .

p 30 in CLASS NOTES :

p 30

Checklist of Direct Observations of Recent Climate Change:

etc., etc.

HAVE A GREAT WEEKEND!

GO CATS!