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Core Course Review Documentation

Foundational Component Area: LIFE & PHYSICAL SCIENCES

Component Area Option? No

Proposed Course: Descriptive Astronomy (Phys 1533)Credit Hours: 3 (2 hours lecture, 1 hour lab)Proposed by: Jacqueline DunnDate: January 16, 2013

Please document how the proposed course meets each of the following requirements. (You may provide a written explanation or copy and paste the appropriate information from the syllabus.)

Content: Courses in this category focus on describing, explaining, and predicting natural phenomena using the scientific method.

Descriptive Astronomy covers the basic components of the universe. Students learn how stars and planetary systems are formed, why we have the galaxies that we see, and ultimately how and why the universe exists the way it does. The relationships between the science of astronomy, astronomical beliefs, and various cultures (both historical and current) are also explored. Students are presented with a historical development of the science of astronomy, leading them through the process of the scientific method. Content is addressed through lectures, readings, and hands-on laboratory activities.

SKILLS: Courses involve the understanding of interactions among natural phenomena and the implications of scientific principles on the physical world and on human experiences.

Students will be able to:

Explain the development of the universe beginning with the Big Bang and ending with the formation and evolution of our solar system.

Apply the scientific method in evaluating scientific theories. Acknowledge commonly held biases and recognize the impact those biases can have on

their evaluation of scientific theories. Analyze data to form conclusions regarding various astronomical processes. Recognize the impact of the study of astronomy in their day to day lives.

ASSESSMENT OF CORE OBJECTIVES: Assessments should be authentic, intentional and direct. The following four Core Objectives must be addressed in each course approved to fulfill this category requirement:

Critical Thinking Skills - to include creative thinking, innovation, inquiry, and analysis, evaluation and synthesis of information Critical thinking skills are developed through inquiry-based activities contained in the text Lecture-Tutorials for Introductory Astronomy. A specific tutorial activity used in this assessment is attached in this file. Students will complete the tutorial over the greenhouse effect (at the end of this file). Students will be evaluated to see if they have exceeded the benchmark level of the AACU VALUE Rubric for Critical Thinking (attached in this file).

Communication Skills - to include effective development, interpretation and expression of ideas through written, oral, and visual communication Oral communication skills are developed through preparation of PowerPoint presentations concerning the impact of astronomy on a culture of their choice and written communication skills are developed through an accompanying paper. Students are assigned a semester project that consists of a three-page paper and five to ten minute presentation on the astronomical beliefs of a culture of their choice. Students will be evaluated to see if they have exceeded the benchmark level of the Assessment for Communication Skills Rubric (see attachment in this file), which focuses on Visual Communication, and has been created based on the AACU VALUE Rubrics for Oral and Written Communication (attached).

Empirical and Quantitative Skills - to include the manipulation and analysis of numerical data or observable facts resulting in informed conclusionsEmpirical analytical skills and quantitative skills are developed through assigned readings and laboratory activities that require students to gather and analyze data. The specific assessment used in this course is a laboratory exercise where students are asked to draw conclusions based on data collected relating to the colors of galaxies (see attached in this file). Students will be evaluated to see if they have exceeded the benchmark level of the AACU VALUE Rubric for Quantitative Literacy (attached in this file).

Teamwork - to include the ability to consider different points of view and to work effectively with others to support a shared purpose or goal Teamwork skills are developed through group projects in class and in the laboratory along with group discussions based on the Lecture Tutorials mentioned above (an example is attached in this file). The specific assessment will be for the Lecture Tutorials on the Greenhouse Effect, also used to assess Critical Thinking. For students who meet in class, the assessment is based on their participation in the group work sessions. For students who take the online section of the course, the assessment is based on their participation in the assigned associated discussions. In both cases, students will be evaluated to see if they have exceeded the benchmark level of the AACU VALUE Rubric for Teamwork (attached in this file).

ADDITIONAL INFORMATION: Provide any additional information supporting course inclusion in the core (optional).Descriptive Astronomy provides students with a great foundation in general science and is it includes basic concepts from physics, chemistry, and geosciences in addition to solely astronomical concepts.

PLEASE ATTACH THE FOLLOWING1. Syllabus2. Assessment for Critical Thinking Skills3. Assessment for Communication Skills4. Assessment for Empirical & Quantitative Skills5. Assessment for Teamwork

Phys 1533 – Descriptive AstronomyOnline Section

Instructor: Dr. Jackie DunnOffice: McCoy Hall, 219DOffice Phone: (940) 397-4184 (less reliable)Email: [email protected] (more reliable)

Textbook: Astronomy, A Beginner’s Guide to the Universe, 6th Edition with MasteringAstronomy by Chaisson & McMillan (ISBN: 0321598768) and Lecture-Tutorials for Introductory Astronomy, 2nd Edition by Prather, Slater, Adams, & Brissenden (ISBN: 0132392267)

Grading: Labs – 15%, Homework/Quizzes – 15%, Project – 15%, Discussion/Participation – 10%, Exams (3 @ 15% each) – 45%

Course Description: This course is designed to introduce the student to the basic concepts of astronomy. AKA The Universe in a Semester.

Lab: Labs will sometimes come from the Lecture Tutorials handbook, other times it will involve making use of resources available on the internet.

Expectations: Students should read the chapters to be covered prior to looking over the lectures and attempting any assignments.

Cheating and plagiarism will not be tolerated. If you take a direct quote from a source for one of your assignments, please indicate so by using quotation marks and citing the source. It should go without saying that any work you hand in should be your own.

Note: In accordance with the law, MSU provides students with documented disabilities academic accommodations. If you are a student with a disability, please contact me.

Note: By enrolling in this course, the student expressly grants MSU a "limited right" in all intellectual property created by the student for the purpose of this course. The "limited right" shall include but shall not be limited to the right to reproduce the student's work product in order to verify originality and authenticity, and for educational purposes.

Exams: Exams will be made available on the dates listed below. The final exam will be cumulative. Each exam will be available online for approximately 1 week. Unless you make arrangements with me prior to the exam, there will be no exceptions to the due dates. Exams will be timed exercises. You will receive more information on their format one week prior to the first exam.

Exam 1: September 29, 2012Exam 2: November 10, 2012Final Exam: December 8, 2012

mailto:[email protected]

Schedule of Topics:

Assessment for Critical Thinking Skills

Lecture-Tutorials for Introductory Astronomy, 2nd Edition by Prather, Slater, Adams, & Brissenden (ISBN: 0132392267)

The lecture tutorials are self-contained exercises designed to be completed within about 15 minutes. Each tutorial covers a different subject matter within astronomy. The students are led through a series of questions in such a way that they will normally recognize any misunderstandings on their in the end (basically, the same question is posed to them in different forms multiple times.) Some tutorials involve interpreting data or diagrams to draw conclusions. The students discuss their answers with each other in small groups and attempt to reach a consensus.

The specific lecture tutorial used to assess Critical Thinking in PHYS 1533 is over the Greenhouse Effect. The tutorial is attached at the end of this file.

The AACU critical thinking rubric is applied (see below).

Capstone4

Milestones3 2

Benchmark1

Explanation of issues

Issue/problem to be considered critically is stated clearly and described comprehensively, delivering all relevant information necessary for full understanding.

Issue/problem to be considered critically is stated, described, and clarified so that understanding is not seriously impeded by omissions.

Issue/problem to be considered critically is stated but description leaves some terms undefined, ambiguities unexplored, boundaries undetermined, and/or backgrounds unknown.

Issue/problem to be considered critically is stated without clarification or description.

EvidenceSelecting and using information to investigate a point of view or conclusion

Information is taken from source(s) with enough interpretation/evaluation to develop a comprehensive analysis or synthesis.Viewpoints of experts are questioned thoroughly.

Information is taken from source(s) with enough interpretation/evaluation to develop a coherent analysis or synthesis.Viewpoints of experts are subject to questioning.

Information is taken from source(s) with some interpretation/evaluation, but not enough to develop a coherent analysis or synthesis.Viewpoints of experts are taken as mostly fact, with little questioning.

Information is taken from source(s) without any interpretation/evaluation.Viewpoints of experts are taken as fact, without question.

Influence of context and assumptions

Thoroughly (systematically and methodically)

Identifies own and others' assumptions and several relevant

Questions some assumptions. Identifies several relevant contexts

Shows an emerging awareness of present

analyzes own and others' assumptions and carefully evaluates the relevance of contexts when presenting a position.

contexts when presenting a position.

when presenting a position. May be more aware of others' assumptions than one's own (or vice versa).

assumptions (sometimes labels assertions as assumptions). Begins to identify some contexts when presenting a position.

Student's position (perspective, thesis/hypothesis)

Specific position (perspective, thesis/hypothesis) is imaginative, taking into account the complexities of an issue.Limits of position (perspective, thesis/hypothesis) are acknowledged.Others' points of view are synthesized within position (perspective, thesis/hypothesis).

Specific position (perspective, thesis/hypothesis) takes into account the complexities of an issue.Others' points of view are acknowledged within position (perspective, thesis/hypothesis).

Specific position (perspective, thesis/hypothesis) acknowledges different sides of an issue.

Specific position (perspective, thesis/hypothesis) is stated, but is simplistic and obvious.

Conclusions and related outcomes (implications and consequences)

Conclusions and related outcomes (consequences and implications) are logical and reflect student’s informed evaluation and ability to place evidence and perspectives discussed in priority order.

Conclusion is logically tied to a range of information, including opposing viewpoints; related outcomes (consequences and implications) are identified clearly.

Conclusion is logically tied to information (because information is chosen to fit the desired conclusion); some related outcomes (consequences and implications) are identified clearly.

Conclusion is inconsistently tied to some of the information discussed; related outcomes (consequences and implications) are oversimplified.

Assessment for Communication Skills

Students are assigned a semester project that consists of a three page paper and five to ten minute presentation on the astronomical beliefs of a culture of their choice.

Paper Rubric:

Points 5 3 1Grammar No more than a few

typos or other grammatical problems.

More than four typos per page or other significant grammatical error.

Significant grammatical problems (poor sentence structure, etc.) and many misspelled words.

Style Paper flows naturally and paragraphs are used correctly.

Transitions between topics may be occasionally sudden or topics may be grouped together inappropriately.

Paper is written without any paragraphs or jumps from one topic to the next with no transitions.

Content Paper is 3 full pages in length. Covers an appropriate breadth of topics and topics are not repeated.

Content is slightly repetitive. Paper may be just shy of 3 full pages in length.

Paper is less than 2.5 pages in length. Ideas are repeated multiple times.

References Has required minimum of 3 references, with at least 1 print reference. Citations are used correctly throughout.

Has 3 references, but all are internet sources. Only has 2 references. Missing some citations within the text.

Lacks any references, or includes a reference list without including any citations within the body of the paper.

Presentation Rubric:

Points 5 3 1Content Appropriate amount

of content to fill the allotted time.

Slightly less or more content than what was needed for the allotted time (under or over by less than a two minutes).

Significantly less or more content than what was needed for the allotted time (under or over by more than two minutes).

Creativity Uses graphics appropriately and often. May make use of props.

Uses graphics appropriately, but doesn’t include any extras (no props).

Little or no graphics.

Style Speaks to audience. No significant breaks in speech. Conducted in a professional manner.

Loses train of thought but recovers well. Conducted in a less serious manner (too many jokes, not

Rarely or never makes eye contact with audience. May treat entire talk as a joke. Not

formal enough, etc.) or reads straight from paper.

professional at all.

Assessment for Empirical & Quantitative Skills

Students are assigned a laboratory exercise where they gather archived information on the colors of galaxies and then use that information to answer specific questions about what types of stars are most likely present based on the color information. The exercise is copied below, after the rubric.

The AACU quantitative literacy rubric is applied (copied below).

Capstone4

Milestones3 2

Benchmark1

InterpretationAbility to explain information presented in mathematical forms (e.g., equations, graphs, diagrams, tables, words)

Provides accurate explanations of information presented in mathematical forms. Makes appropriate inferences based on that information. For example, accurately explains the trend data shown in a graph and makes reasonable predictions regarding what the data suggest about future events.

Provides accurate explanations of information presented in mathematical forms. For instance, accurately explains the trend data shown in a graph.

Provides somewhat accurate explanations of information presented in mathematical forms, but occasionally makes minor errors related to computations or units. For instance, accurately explains trend data shown in a graph, but may miscalculate the slope of the trend line.

Attempts to explain information presented in mathematical forms, but draws incorrect conclusions about what the information means. For example, attempts to explain the trend data shown in a graph, but will frequently misinterpret the nature of that trend, perhaps by confusing positive and negative trends.

RepresentationAbility to convert relevant information into various mathematical forms (e.g., equations, graphs, diagrams, tables, words)

Skillfully converts relevant information into an insightful mathematical portrayal in a way that contributes to a further or deeper understanding.

Competently converts relevant information into an appropriate and desired mathematical portrayal.

Completes conversion of information but resulting mathematical portrayal is only partially appropriate or accurate.

Completes conversion of information but resulting mathematical portrayal is inappropriate or inaccurate.

Calculation Calculations attempted are essentially all successful and sufficiently comprehensive to solve the problem. Calculations are also presented elegantly (clearly, concisely, etc.)

Calculations attempted are essentially all successful and sufficiently comprehensive to solve the problem.

Calculations attempted are either unsuccessful orrepresent only a portion of the calculations required to comprehensively solve the problem.

Calculations are attempted but are both unsuccessful and are not comprehensive.

Application / AnalysisAbility to make judgments and

Uses the quantitative analysis of data as the basis for




draw appropriate conclusions based on the quantitative analysis of data, while recognizing the limits of this analysis

deep and thoughtful judgments, drawing insightful, carefully qualified conclusions from this work.

competent judgments, drawing reasonable and appropriately qualified conclusions from this work.

workmanlike (without inspiration or nuance, ordinary) judgments, drawing plausible conclusions from this work.

tentative, basic judgments, although is hesitant or uncertain about drawing conclusions from this work.

AssumptionsAbility to make and evaluate important assumptions in estimation, modeling, and data analysis

Explicitly describes assumptions and provides compelling rationale for why each assumption is appropriate. Shows awareness that confidence in final conclusions is limited by the accuracy of the assumptions.

Explicitly describes assumptions and provides compelling rationale for why assumptions are appropriate.

Explicitly describes assumptions.

Attempts to describe assumptions.

CommunicationExpressing quantitative evidence in support of the argument or purpose of the work (in terms of what evidence is used and how it is formatted, presented, and contextualized)

Uses quantitative information in connection with the argument or purpose of the work, presents it in an effective format, and explicates it with consistently high quality.

Uses quantitative information in connection with the argument or purpose of the work, though data may be presented in a less than completely effective format or some parts of the explication may be uneven.

Uses quantitative information, but does not effectively connect it to the argument or purpose of the work.

Presents an argument for which quantitative evidence is pertinent, but does not provide adequate explicit numerical support. (May use quasi-quantitative words such as "many," "few," "increasing," "small," and the like in place of actual quantities.)

Assessment for Teamwork

Sections that meet on campus:

Lecture-Tutorials for Introductory Astronomy, 2nd Edition by Prather, Slater, Adams, & Brissenden (ISBN: 0132392267)

The lecture tutorials are self-contained exercises designed to be completed within about 15 minutes. Each tutorial covers a different subject matter within astronomy. The students are led through a series of questions in such a way that they will normally recognize any misunderstandings on their in the end (basically, the same question is posed to them in different forms multiple times.) Some tutorials involve interpreting data or diagrams to draw conclusions. The students discuss their answers with each other in small groups and attempt to reach a consensus. A sample lecture tutorial is attached at the end of this file.

Sections that meet online only:

Based on the same assignments above, students are required to participate in online discussions of the answers for selected tutorials. The instructor only gives students the correct answers if the group as a whole fails to reach a consensus through these discussions. The goal of the discussions is to mimic the work done in person within a small group as much as is possible in the online environment.

In both cases above, the AACU teamwork rubric is applied (copied below).

Capstone4

Milestones3 2

Benchmark1

Contributes to Team Meetings

Helps the team move forward by articulating the merits of alternative ideas or proposals.

Offers alternative solutions or courses of action that build on the ideas of others.

Offers new suggestions to advance the work of the group.

Shares ideas but does not advance the work of the group.

Facilitates the Contributions of Team Members

Engages team members in ways that facilitate their contributions to meetings by both constructively building upon or synthesizing the contributions of others as well as noticing when someone is not participating and inviting them to engage.

Engages team members in ways that facilitate their contributions to meetings by constructively building upon or synthesizing the contributions of others.

Engages team members in ways that facilitate their contributions to meetings by restating the views of other team members and/or asking questions for clarification.

Engages team members by taking turns and listening to others without interrupting.

Individual Contributions Outside of Team Meetings

Completes all assigned tasks by deadline;work accomplished is thorough, comprehensive, and advances the project.Proactively helps other team members complete their assigned tasks to a similar level of excellence.

Completes all assigned tasks by deadline;work accomplished is thorough, comprehensive, and advances the project.

Completes all assigned tasks by deadline;work accomplished advances the project.

Completes all assigned tasks by deadline.

Fosters Supports a constructive Supports a constructive Supports a constructive Supports a constructive

Constructive Team Climate

team climate by doing all of the following:

• Treats team members respectfully by being polite and constructive in communication.

• Uses positive vocal or written tone, facial expressions, and/or body language to convey a positive attitude about the team and its work.

• Motivates teammates by expressing confidence about the importance of the task and the team's ability to accomplish it.

• Provides assistance and/or encouragement to team members.

team climate by doing any three of the following:





team climate by doing any two of the following:





team climate by doing any one of the following:





Responds to Conflict

Addresses destructive conflict directly and constructively, helping to manage/resolve it in a way that strengthens overall team cohesiveness and future effectiveness.

Identifies and acknowledges conflict and stays engaged with it.

Redirecting focus toward common ground, toward task at hand (away from conflict).

Passively accepts alternate viewpoints/ideas/opinions.

Greenhouse Effect

Section 1: Effective temperature of Earth

The Earth system gives off the same amount of energy that it absorbs from the Sun. If this did not happen and our planet absorbed more energy than it gives off, Earth would continuously become warmer and warmer.

Incoming Solar Radiation Outgoing Planet Radiation

By setting the incoming solar radiation absorbed by Earth equal to the outgoing radiation emitted by Earth, we can estimate that the effective temperature of Earth would be 255K (0F). Note that this estimate assumes that Earth has no atmosphere and reflects 30% of the incoming sunlight.

1) How would the surface of our planet be different if its temperature was 0F?

2) Give one possible reason why the average surface temperature of our planet actually turns out to be much warmer at 288K (58F).

Section 2: Photon spectrum versus solar spectrum

3) Does a photon with a short wavelength have more or less energy than a photon with a long wavelength?

In the graphs below, the wavelength of a given photon is shown on the horizontal axis. The energy per photon is shown on the vertical axis. The line or curve drawn is provided to illustrate the relationship between the energy of a photon versus the wavelength of that photon.

CAPER TEAM LECTURE-TUTORIALS FOR INTRODUCTORY ASTRONOMYDRAFT EDITION, 2005

18

Greenhouse Effect

4) Which graph above most correctly represents how you think the energy of a photon is related to its wavelength? Explain your answer.

The previous two questions dealt with the energy of an individual photon. However, objects give off different numbers of photons at each wavelength depending upon their temperature. Figure 1 below shows the energy spectrum for our Sun along with the percent of energy radiated by the Sun in the ultraviolet (UV), visible, and infrared portions of the electromagnetic spectrum.

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 15000

1

2

3

4

5

Solar Spectrum

Wavelength (nm)

Ener

gy U

nits

Figure 1

5) How many times greater is the amount of visible light given off by the Sun compared to the amount of ultraviolet light given off by the Sun? Show how you got to this result.


19

X-ray UV VIS IR Radio

wavelength longshortX-ray UV VIS IR Radio

wavelength longshortX-ray UV VIS IR Radio

wavelength longshort

A B C

UV7%

VIS44%

IR37%

Ener

gy p

er p

hoto

n

Ener

gy p

er p

hoto

n

Ener

gy p

er p

hoto

n

Greenhouse Effect

6) Why aren’t x-ray and ultraviolet photons as important for heating Earth as visible and infrared photons?

7) Consider the following debate between two students regarding the energy given off by the Sun.

Student #1 – I think that the Sun gives off most of its energy at ultraviolet wavelengths because ultraviolet light is more intense than visible light and more efficient at carrying energy.

Student #2 – Actually, x-rays are even more energetic than ultraviolet photons. Shouldn’t they be the most important energy source coming from the Sun?

Student #3 – Hold up, even though UV and x-ray photons are more energetic than visible photons, the Sun gives off way more visible and infrared photons. So I think that these longer wavelength photons account for most of the energy coming from the Sun.

Do you agree and/or disagree with any or all of these students? Explain your reasoning.


20

Greenhouse Effect

Section #3: Atmospheric absorption of light

The temperature of the surface of our planet is affected primarily by the energy we receive from the Sun that is able to reach Earth’s surface. However, a photon’s ability to penetrate all the way through our atmosphere and reach the ground depends upon its wavelength. Figure 2 below shows that certain wavelengths of light are absorbed in our atmosphere before they can travel all the way to the surface of Earth.

8) Light is absorbed at each of the following wavelengths. For each, list the molecule(s) in the atmosphere that is responsible for this absorption.

Wavelength Molecule(s) Responsible for Absorption1.4 microns

1.7 microns

2.7 microns

6 microns

9 microns

15 microns

30-100 microns

9) Roughly what percentage of ultraviolet light (between 0.1-0.4 microns) is absorbed before reaching Earth’s surface? Describe the difference in absorption between UV light with shorter wavelengths (0.1 – 0.3 microns) and UV light with longer wavelengths (0.3 – 0.4 microns).

10) Roughly what percentage of visible light (between 0.4-0.7 microns) is absorbed before reaching Earth’s surface?


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Figure 2

Taken from Goody & Walker, Atmospheres, Prentice-Hall: 1972.

H2O

O2 & O3 H2O H2O CO2 CO2 H2O O3 CO2 H2O (rotation)

IRVISUV

Greenhouse Effect

11) Comparing the visible and the infrared parts of the spectrum, which would you say has an easier time getting through our atmosphere?

12) Compare the absorption graph in Figure 2 with the energy spectrum of our Sun in Figure 1. Which wavelength of light would you say is most responsible for heating the surface of our planet? Explain your answer and refer to both figures in your explanation.

Section 4: Spectrum from Earth’s surface

Once visible light from the Sun reaches the surface of Earth, it can either be reflected back towards space as visible light or be absorbed by the ground. This absorbed visible light causes the temperature of the surface to increase. The ground then gives off energy based upon its increased temperature.


21

longlong

Energy

short longX-ray UV VIS IR Radio

wavelength

CB

Energy

shortX-ray UV VIS IR Radio

wavelength

A

Energy

shortX-ray UV VIS IR Radio

wavelength

Greenhouse Effect

13) Which of the diagrams (A, B, or C) above most accurately represents the energy given off by Earth’s surface as a function of wavelength? Explain your reasoning.

14) At what wavelength does Earth’s surface give off the most energy?

15) Will the light given off by Earth’s surface easily travel back through the atmosphere to space or will it be absorbed by molecules in the atmosphere? Explain your reasoning.

16) What happens to the temperature of the atmosphere as it absorbs light from either the Sun or from Earth’s surface?

Section 5: The Greenhouse Effect

You should now have a picture of visible light traveling all the way through the atmosphere to the surface of Earth while infrared light (both from the Sun and from Earth’s surface) cannot travel very far through the atmosphere without being absorbed. It is important to note that this absorbed infrared light doesn’t disappear and also isn’t trapped in the atmosphere forever; rather, it simply travels a shorter distance through the atmosphere before it is absorbed and then given off again in a random direction. So, while visible light can travel all the way through the atmosphere without being absorbed, infrared light is continuously absorbed and given off and absorbed and given off many times as it travels through the atmosphere.


22

Greenhouse Effect

The diagrams below show possible paths for visible and infrared light as they travel through Earth’s atmosphere. Visible light is represented with dashed arrows; infrared light is shown with solid arrows. Note that three out of the eight diagrams properly depict possible paths for visible and infrared light through the atmosphere.


23

VIS

VISIR

IR

IR

VIS VIS

IR VIS

IR IR

VIS IR

IR

IR

IR

A B C D

E F G H

Earth’s surface

top of atmosphere

Earth’s surface

top of atmosphere

Greenhouse Effect

17) List the FIVE diagrams that incorrectly depict how visible and infrared light travel through the atmosphere? For each, describe what is wrong with the diagram.

18) Of the remaining three diagrams, which shows visible light reflecting off the surface of the earth and traveling back out to space as visible light? If this light is completely reflected, does it do any heating of the surface?

19) In the space below, redraw the TWO diagrams that properly show how visible and infrared light travel through the atmosphere and lead to an enhanced surface temperature.


24

top of atmosphere

Earth’s surface

Greenhouse Effect

20) What is the source of visible photons that heat the surface of Earth? What are the TWO sources of infrared photons that heat the air in our atmosphere?

21) If the surface of Earth immediately gave off to outer space the same amount of energy as it received from the Sun, the surface would be 255K (0F). Where does the additional energy come from that heats the surface of Earth to its measured value of 288K (58F)?

The transfer of energy that you diagrammed in Question #19 is the source of the natural “Greenhouse Effect.” Because Earth has an atmosphere that inhibits the transport of infrared light, the atmosphere becomes warmer and gives energy back to the surface, leading to a surface temperature that is 58F warmer than Earth’s effective temperature of 255K (0F).

22) Go back to your answer to Question #8. What are the primary “greenhouse gases” in our atmosphere? What characteristic makes them greenhouse gases?

23) Imagine that in the middle of the night you pointed a very sensitive infrared camera at the sky and took a picture. Would your picture be dark (indicating no detected infrared light) or bright (indicating many infrared photons)? Explain your reasoning.

24) Is your answer to Question #23 consistent with what you know about the greenhouse effect? Why or why not?


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