light earth atm spr2010 notes
TRANSCRIPT
8/8/2019 Light Earth Atm Spr2010 Notes
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Light & Earths atmosphere
Chapters 5 and 10
(Hints of chapter 2, more later)
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Learning Outcomes, Objectives, & Goals Appreciating science in general, and astronomy in specific.
Understanding how knowledge is gained and be critical of what yousee and hear.
Developing a working knowledge of the scientific method and how to
apply it to real world situations.
Critically analyzing and evaluating information, scientific or
otherwise
Learn some simple astronomical nomenclature/terminology.
Develop a sense of what scientists know about the overall universe,
its constituents, and our location
Explain how electromagnetic radiation is used to reveal the
properties of stars and planets.
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Student Learning Outcomes
Understand the major properties of light, includingwave and particle properties.
Know the 7 types of light and the order of the majorwave & particle properties for these types.
Understand how light and matter interact, in bothdistant and everyday objects. (Including Dopplereffect.)
Understand the nature of light properties and its
relationship to the ozone hole and why this is aproblem.
Understand the nature of light properties and itsrelationship to global warming. Know the majormanmade causes of global warming.
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Fancy words
Visible light
___________
Visible spectrum White
______________________
_______________________
= ___________________
= ________________________
=
_______________= _________________________
_______________________
= ___________
= ________________
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Wave (Light) properties
_____________ see page 149
_____________ ___________________________
±units are: _____________________________________
Speed = how fast _________________________
± ____________________
±
___________________________________________ __________________________________________
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5 ways light interacts with matter1. ______________. Well discuss 2 ways later.
2. __________________
3. ________________________________
4. __________________(___________things)
5. _______________________(______things)
See figures 5.2 & 5.3 on pages 151-152.
Why is the sky blue? _____________! See pages304-305 (not on your test)
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Which one of these 5 interactions
causes damage to cells?
0
0
0
0
0 1. Emission
2. Absorption
3. Transmission (Passing through)4. Reflection
5. Scatters
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Which does a movie screen do?
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0
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0 1. Scatter
2. Reflect
3. Emit4. Absorb
5. Transmit
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Which happens to light when it hits my
shirt?
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0 1. Scatter
2. Reflect
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Which happens to light when it hits the
Moon?
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0 1. Scatter
2. Reflect
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What color does a green shirt ABSORB?
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0 1. Absorb all except green light
2. Absorb green light
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Calif. Elementary School Science Standards
for energy & seasons
From California Science Standards, grade 3:
± Students know energy comes from the Sun to Earth in the
form of light.
And from grade 6: ± Students know solar energy reaches Earth
through radiation, mostly in the form of visible
light.
And from grade 7: ± Students know visible light is a small band within a
very broad electromagnetic spectrum.
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Calif. Science Standards for light
From California Science Standards, grade 3:
±
Students know the color of light striking anobject affects the way the object is seen.
± Students know an object is seen when lighttraveling from the object enters the eye.
And from grade 7:
± Students know that for an object to be seen,light emitted by or scattered from it mustbe detected by the eye.
± Students know light travels in straight lines if
the medium it travels through does not change. ± Students know that white light is a mixture of
many wavelengths (colors)
± Students know light can be reflected,refracted, transmitted, and absorbed by
matter .
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Planet temperature
Depends on two things:
1. ______________________________________
2. ______________________________________
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Light types _______________types of ____________(see page ____).
_______________________!S
ee percentages below.(__________________________________________)
1. _______________________
2. _______________________
3. _______________________
4. _______________________
5. _______________________
6. _______________________7. _______________________
(__________________________________________) _____________________________________________________________________
_____________________________________________________________________
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Sunlight emission
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Pictures of Sun in 6 of 7 light types
X-ray UV Visible
IR Microwave Radio
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Light in your everyday life Your eyes see ___________ light.
When ________ light lands on your skin, skin gets warmer.
When ________ light lands on your skin, skin is damaged.
When ________ light lands on your skin, you get radiation
poisoning. (two answers)
When ________ light lands on your skin, nothing changes
unless a LOT lands on you. (two answers)
Digital cameras see visible AND infrared light. Remotecontrols often use IR light. Look: cell phone + remote
Blacklights emit UV light.
± Take a look Moon lights, portable UV lights.
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Photons and humans
Which type of photon carries the most
energy?
Which kind is most dangerous? Least dangerous?
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Light acting as a particle
___________________________
_________also _________________.
Light _____________________.
What are the 7 types of light?
They differ in ______________, ___________,
and _________________________.
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Sources of cooling1. ____________________
± Which kind of light does the Sun shine most?
± Objects _______________cool mostly by _________ _____________________. (See page 168 Wiens law)
± Colder objects also ________________________(Stefans law, p. 168)
2. Other cooling methods inside planets
± Similarly, can ignore these again
For the rest of this course, well focus on: ± ___________________________________
For OUR solar system, that means focusing on: ± _______________________________. Why _________light?
± Which other type of light should we focus on?
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Using light to identify properties
Objects can ______________________________:1. Because ______________________
± These _________________________, but _______________________.
± Examples: the __________, ___________________________
±Which kind given off most by _________? ______________? ___________light indicates ____________________.
2. Because they are _________________________ ± These give off ______________ (well see)
Called ________________ or _____________________
± Example: fluorescent gas tubes well see
± Useful to astronomers because __________ ___________________________________
± Show animation: Composition of Mystery Gas [4th row from bottom]
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Light wave properties & human
influences
Now that you understand the basics of light
properties, lets examine two issues related to
humans and the Earth.
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The Ozone Layer Ozone is a form of molecular ________________________.
Occurs naturally (if the atmosphere already has O2) in the _______
___________________in small quantities (parts per trillion).
_______________________________________________very
efficiently (90-99% of them).
Without it, _____________________________________________ ________________________________________________________
________________________________________________________
Chloro-Fluoro-Carbons (_____ ) produced by humans are nearly
inert molecules that get into the upper atmosphere. CFCs attack the ozone molecules. Each _____molecule destroys
____________ozone molecules over its several year lifetime before
the _______molecule is finally destroyed. (No convection in upper
atmosphere. See pages305
,324-325
.)
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The worst damage, by far, occurs
over ____________.
Ozone Hole over Antarctica
Fortunately ________________!There are also precious few
_________________there. How
lucky!
Equally fortunate is that we found this problem and its cause in
time! Here is a more recent map of the ozone layer. It¶s not as good as we¶d hoped.
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CFCs in our atmosphere
Production of ______were banned worldwide in _____. Look at the chart after _____. _________are dropping! Predictions were that the worst damage to the
ozone layer would occur by 2000, and then it would start ³healing´. BUT: in
2007, the hole got bigger. Hopefully the healing will (re-?)start soon!
EXPECTEDTO BE BACK TO NORMAL LEVELS IN ______________
Important point: international effort was necessary and seems to be working.
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Human influences & economics
Until recently, people assumed we couldnt affect
the atmosphere.
Then we started measuring it.
Ozone hole showed up. Nobody expected it.
It cost a LOT of money to stop damaging the ozone
layer.
It was money we HAD to spend to keep life alive.
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Human influences & economicsPeople didnt believe the ozone hole was caused byhumans. They claimed:
± FIRST: Its not happening
± SECOND: It might be natural; Earth goes through cycles.
Were not making enough stuff to cause the damage.
± NOW:
We dont know enough (its too early) to make any major changes It might naturally fix itself; life has been on Earth for billions of years. Itll
adapt and solve this problem.
The economy would suffer if we force ourselves to change our ways
Same argument used for cigarettes & lung cancer, seat belts, airbags, car
catalytic converters, and sulfur dioxide emissions (that cause acid rain).Using same argument now to prevent increasing fuel economy. Historyshows these economic arguments were often wrong.
These EXACT same arguments are now being used whendiscussing global warming.
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New topic coming up. First I get your
thoughts.
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What would happen if we wrapped theEarth in an ___________________ _____________________? Talk toyour neighbor. Ill solicit answers from
you.
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What would happen IN THE LONG TERM if wewrapped the Earth in an ___________________ __________________?
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0
0 1. Earth would cool down
2. Earth would get hotter
3. Earth would stay same
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Global Warming
The fundamental idea about global warming
and the potential dangers deals with the
_______________________ portion of Earths
___________________________.
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Greenhouse effect Did we use the infrared camera?
Did we see people wearing glasses on the infraredcamera?
What did that mean?
What happens when you surround Earth with an IRblocking gas?
This is called the Greenhouse effect.
Two key ideas: ± Visible light from Sun comes in, warming Earth up
± Infrared light from Earth gets blocked by someGreenhouse agent, so Earth cant cool as easily
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Greenhouse Agents and effects Some ____________are __________________
± ____________________________________________
± ________________________________(methane is 23x better!)
± _________________. But lots of it in Earths atmosphere, whichcauses most of our Greenhouse Effect.
Greenhouse atmosphere _________________________. Earth would be _________________than it is without G.E.!
± Water would _____________! (Avg temp: 3 F or -16 C)
Which planet do you think should be hottest?
± Why?
Does Venus have an atmosphere?
Why is ______________________________?
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From James Hansens PowerPoint downloaded from his NASA Goddard web page. The next
slides graphs are from an article he wrote a few years ago. This graph was SET to zero for a
specific year. The century-long change is the important idea here.
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Global Warming The FactsThe temperature of the Earth is _______
______________(___________graph).
We see: average temperature of Earth
has increased about ________________
_____________.This is much faster than
scientists can explain without human
influence.
Coincides with huge increase in CO2
from burning fossil fuels. Levels now
higher than any level seen in past400,000 years and rising. (Was 280 ppm in
1850; in 2009 it¶s 387 & rising 2.4/yr. In 1980¶s rose
1.4 ppm/yr, <1ppm/yr before then)
Other changes: sea level has risen,
carbonation in the oceans increased (i.e.
oceans are storing much of our CO2).
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Global Warming related facts People make lots of _______________________________________
Both of these gases cause the ___________________________.Most from the ________________burning fossil fuels. _______CO2
emitters. (But China has 4x the US population! Use LOTS of coal!)
Cutting down/burning trees (deforestation) is also a major factor.
Do we understand EVERYTHING about the temp increase?
Of course not. Atmosphere = complicated. New data every day.
Your book gives an objective summary on pages 328-330.
NOTE: While humans account for 2 percent of the worlds carbon
dioxide emissions. Thats enough to tip the balance, though.
__________________________________________________________.
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What people think about
global warming part 1
Youve probably heard about the controversy
surrounding global warming.
Here are facts:
1._____________who understands the data _____
_________________________________. ____% of
scientists agree the temperature is rising in the __________term (over _________________).
2.The only controversy ___________________the
temperature to rise.
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What people think about
global warming part 2o ______(___ % of) scientists who study the Earth¶s
LONG-term atmosphere believe manmade _____
_____________________________
o Even 90% of ALL 3,146 earth scientists surveyedagreed temperatures are rising, and 82% said
³human activity [has] been a significant factor«´
o
However, some deniers say that we don¶t knowenough yet to say what¶s going on.
oMostly petroleum geologists & meteorologists
oMeteorologists study SHOR T-term effects.
oSource: http://www.cnn.com/2009/WORLD/americas/01/19/eco.globalwarmingsurvey/index.html
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IPCCIntergovernmental Panel on Climate Change
IPCC = group of ~2000 atmospheric scientists
IPCCs 4th report (2007):
Greenhouse gas emission rate has increased 70% since
1970.
Warming of the climate system is unequivocal.
90% likelihood that human activity is affecting the climate.
Under current policies, emission will continue to increase
for decades to come.
If we continue to do what we are doing now, we are in
deep trouble. - Ogunlade Davidson, IPCC
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Five Biggest CO2 emitters (as of 2004)
1. _______________
2. _____________
3. Russia
4. Japan
5. IndiaBut if we separate the US into states«
1. China
2. Russia
3. Japan
4. India
And my personal favorite:
5. ____________
« 12. __________________ China has now (in 2008) overtaken the US in
total CO2.
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Five Biggest CO2 emitters PER PERSON (as of
June 2008)
1. USA ± 19.4 tons per year
2. Russia ± 11.8 tons
3. European Union ± 8.6 tons
4. China ± 5.1 tons
5. India ± 1.8 tons
Driving 12,000
miles releases ~6
tons CO2.(average;
Prius is ~2.5 tons)
Chinas rate is growing faster than the US, largely due
to coal and cement plants. But they have a lot of
catching up to do.
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Other possible causes of global warming
Bottom line: Most scientists predict _____________
__________________________________________,
____________________________________.
Other things may explain the temp raise during the last 100
years.__________________________.
(This is the _____________________________.)
_________________( M aunder M inimum). ___________=
_____________. Not well understood. But _________link.We thought this is the strongest sunspot cycles during
the last 50 years. But as of Apr 2009 we may be in the
deepest solar minimum in 100 years, so this argument is
less convincing. Stay tuned as we learn more.
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Consequences of global warming
Retreat of glaciers (Apparently happening)
Melting of Greenland & Antarctic ice caps. (Seen;Greenlands caps are melting faster than predicted)
Melting of Arctic permafrost. Melting of Arctic sea ice.
Rising sea level & flooding on coasts.
Stronger hurricanes/storms (a bit more controversial)
Shift of malaria farther from equator. (Seen already)
Similar shift of wine-producing regions. (Seen)
Similar shift of desert belt.
Mass extinctions of wildlife.
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Did Al Gore get the science of global
warming right?
0
0 1. Yes
2. No
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Doppler Effect what is it?
Sound maker demo
± Close eyes & listen; describe
± 440 Hz. F#
± Match description with observation
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Which kind of Doppler shift do we see for
most objects in the universe?
0
0 1. Redshift
2. Blueshift
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Redshift & blueshift
Interactive figure 5.22
Why called redshift & blueshift for light.
Doppler shift of lines [5th
row top] Application in your everyday (?) life:
± Speeding tickets!
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Learning Outcomes, Objectives, & Goals Appreciating science in general, and astronomy in specific.
Understanding how knowledge is gained and be critical of what you
see and hear.
Developing a working knowledge of the scientific method and how to
apply it to real world situations.
Critically analyzing and evaluating information, scientific or
otherwise
Learn some simple astronomical nomenclature/terminology.
Develop a sense of what scientists know about the overall universe,
its constituents, and our location
Explain how electromagnetic radiation is used to reveal theproperties of stars and planets.