Light Earth Atm Spr2010 Notes

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)



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.



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.



Fancy words

Visible light

___________

Visible spectrum White

______________________

_______________________

= ___________________

= ________________________

=

_______________= _________________________

_______________________

= ___________

= ________________



Wave (Light) properties

_____________ see page 149

_____________ ___________________________

±units are: _____________________________________

Speed = how fast _________________________

± ____________________

±

___________________________________________ __________________________________________



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)



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

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80



Which does a movie screen do?

0

0

0

0

0 1. Scatter

2. Reflect

3. Emit4. Absorb

5. Transmit

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80



Which happens to light when it hits my

shirt?

0

0 1. Scatter

2. Reflect

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50



Which happens to light when it hits the

Moon?

0

0 1. Scatter

2. Reflect

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50



What color does a green shirt ABSORB?

0

0 1. Absorb all except green light

2. Absorb green light

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50



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.



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 .



Planet temperature

Depends on two things:

1. ______________________________________

2. ______________________________________



Light types _______________types of ____________(see page ____).

_______________________!S

ee percentages below.(__________________________________________)

1. _______________________

2. _______________________

3. _______________________

4. _______________________

5. _______________________

6. _______________________7. _______________________

(__________________________________________) _____________________________________________________________________

_____________________________________________________________________



Sunlight emission



Pictures of Sun in 6 of 7 light types

X-ray UV Visible

IR Microwave Radio



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.



Photons and humans

Which type of photon carries the most

energy?

Which kind is most dangerous? Least dangerous?



Light acting as a particle

___________________________

_________also _________________.

Light _____________________.

What are the 7 types of light?

They differ in ______________, ___________,

and _________________________.



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?



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]



Light wave properties & human

influences

Now that you understand the basics of light

properties, lets examine two issues related to

humans and the Earth.



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

.)



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.



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.



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.



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.



New topic coming up. First I get your

thoughts.



What would happen if we wrapped theEarth in an ___________________ _____________________? Talk toyour neighbor. Ill solicit answers from

you.



What would happen IN THE LONG TERM if wewrapped the Earth in an ___________________ __________________?

0

0

0 1. Earth would cool down

2. Earth would get hotter

3. Earth would stay same

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50



Global Warming

The fundamental idea about global warming

and the potential dangers deals with the

_______________________ portion of Earths

___________________________.



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



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 ______________________________?



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.



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).



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.

__________________________________________________________.



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.



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



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



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.



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.



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.



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.



Did Al Gore get the science of global

warming right?

0

0 1. Yes

2. No

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50



Doppler Effect what is it?

Sound maker demo

± Close eyes & listen; describe

± 440 Hz. F#

± Match description with observation



Which kind of Doppler shift do we see for

most objects in the universe?

0

0 1. Redshift

2. Blueshift

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80



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!



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.

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