METEO 436 Clothiaux FA14

Radiation and Climate Tu-01:00-02:00 PM (Room 126 Walker) W-05:30-07:00 PM (Room 529 Walker) Th-09:30-11:00 AM (Room 511 Walker) Instructor-Dr Eugene Clothiaux

METEO 436: Radiation and Climate


Eugene Clothiaux,


Office Hours:

Tu 01:00-02:00 PM (Room 126 Walker)
W 05:30-07:00 PM (Room 529 Walker)
Th   09:30-11:00 AM (Room 511 Walker)
By Email Appointment

Teaching assistant:

Lee Dunnavan


Office Hours:

Tu 01:45-02:20 PM (Room 126 Walker)
Th 09:30-11:00 AM (Room 511 Walker)
Drop in (Room 530 Walker)
By Email Appointment

Support services available: None

Class meeting times and locations:

Monday, Wednesday and Friday 1:25-2:15 PM; Room 012 Walker Building

Course designation in curriculum:

Choice of 1 of 3 Courses Required for the Major

Brief course description from University Bulletin: at

“This course covers radiation and how it interacts with the atmosphere and earth's surface to drive motions in the atmosphere. The fundamentals of radiative transfer at the molecular level, including absorption, scattering, transmission, and emission of radiation by matter, are discussed and applied to help describe the earth's energy budget. Crucial to understanding these processes in the atmosphere are the interactions of radiation with water in the vapor, liquid, and solid states. Applications of radiative transfer to the understanding of seasons and of climate and climate change are presented as well.”

Prerequisites and concurrent courses:

METEO 300 is a prerequisite for this course while METEO 431 must at least be concurrent with this course. Mathematics through differential equations is a necessity for this course. A basic understanding of atmospheric thermal physics and classical electromagnetic theory is helpful, though all ideas pertinent to this course will be introduced within it.

Students who do not meet these prerequisites after being informed in writing by the instructor may be dis-enrolled during the first 10-day free add-drop period: http:/ . If you have not completed the listed prerequisites, then promptly consult with the instructor if you have not done so already. Students who re-enroll after being dis-enrolled according to this policy are in violation of Item 15 on the Student Code of Conduct: .

Required textbooks and recommended textbooks:

No book is absolutely required for this course. The one closest in content to the course content is "Fundamentals of Atmospheric Radiation" by Craig Bohren and Eugene Clothiaux as it is hard to ignore the ideas that one has written about in a text book.

Reserve materials (EMS Library in the Deike Building):

  • C.F. Bohren Clouds in a Glass of Beer
  • C.F. Bohren What Light Through Yonder Window Breaks?
  • R.M. Goody and Y.L. Yung Atmospheric Radiation (2nd Edition)
  • K.N. Liou An Introduction to Atmospheric Radiation (2nd Edition)
  • G.W. Petty A First Course in Atmospheric Radiation (2nd Edition)
  • M.L. Salby Physics of the Atmosphere and Climate (2nd Edition)
  • G.L. Stephens Remote Sensing of the Lower Atmosphere
  • G.E. Thomas and K. Stamnes Radiative Transfer in the Atmosphere and Ocean
  • J.M. Wallace and P.V. Hobbs Atmospheric Science: An Introductory Survey (2nd Edition)
  • J.A. Coakley and P. Yang    Atmospheric Radiation: A Primer with Illustrative Solutions
  • M. Wendisch and P. Yang Theory of Atmospheric Radiative Transfer

Internet materials and links:


Course objectives/outcomes:

Meteorology Courses Objectives and Outcomes printable document contains a link to the Course objectives and outcomes listed below.

Course objectives:

  1. Students can demonstrate how radiative processes are related to atmospheric structure and phenomena (relate to program objectives 1 and 2)
  2. Students can demonstrate the ability to apply atmospheric radiative principles quantitatively to atmospheric problems (relate to program objectives 1 and 3)

Course outcomes:

  • Students can demonstrate knowledge of absorption, emission, and scattering properties along with the equations for radiance, irradiance, and solid angle (relate to program outcomes b and c)
  • Students can demonstrate a basic grasp of the integro-differential form of the radiative transfer equation by providing a physical interpretation (relate to program outcome b)
  • Students can solve the integro-differential form of the radiative transfer equation for simplified atmospheres such as attenuation-only with no scattering (relate to program outcome b and d)
  • Students can demonstrate the use of simplified solutions of the integro-differential form of the radiative transfer equation to basic remote sensing of the atmosphere (relate to program outcomes a and d)
  • Students can show the link of atmospheric irradiance to atmospheric heating and cooling (relate to program outcome b)

Course expectations:

All students will come to class prepared to discuss the course material at hand. Students are allowed to work on homework problems together. But, students must write-up their homework solutions on their own and have complete mastery of what it is that they have written. Students must meet the deadlines for the homework assignments. Habitual tardiness in turning in the homework will lead to a loss of points but only after a warning from the instructor.

Course policies:

This course abides by the Penn State Class Attendance Policy 42-27: , Attendance Policy E-11: , and Conflict Exam Policy 44-35: . Please also see Illness Verification Policy: , and Religious Observance Policy: . Students who miss class for legitimate reasons will be given a reasonable opportunity to make up missed work, including exams and quizzes. Students are not required to secure the signature of medical personnel in the case of illness or injury and should use their best judgment on whether they are well enough to attend class or not; the University Health Center will not provide medical verification for minor illnesses or injuries. Other legitimate reasons for missing class include religious observance, family emergencies, and regularly scheduled university-approved curricular or extracurricular activities. Students who encounter serious family, health, or personal situations that result in extended absences should contact the Office of Student and Family Services for help: . Whenever possible, students participating in University-approved activities should submit to the instructor a Class Absence Form available from the Registrar's Office: , at least one week prior to the activity.

Assessment tools:

For a summary of General and Final Examination Policies 44-10 and 44-20 and alternative assessment practices, please see Examination Policy Summary: and General and Final Exam Policies: .


Required written/oral assignments:

The only written assignments for this course will be homework assignments. The homework assignments must be completed according to course expectations listed above. Homework assignments will compose 20% of the final course grade.

Examination policy:

There will be two mid-term exams, each worth 25% of the final course grade, and a final exam worth 30% of the final course grade. The final exam will be given during the official exam slot scheduled for this course. The mid-term exams will be given at appropriate times during the semester at a time agreed upon by all. There will be an optional presentation available to all students that must be completed within the last month of class, but not the last week, that is worth 25% of the course grade and may be used as a substitute for one of the mid-term exam grades.

Grading policy:

There will be no grade curving. For the final course grade the instructor may throw out poor exam questions and adjust the percentages that homework and exams count. This will be done in the same way for all students and only in such a way as to help each student’s overall course grade. No student will receive a grade less than what is based on the homework (20%), mid-term exams (50%) and final exam (30%) percentages given above.

Academic integrity statement:

Students in this class are expected to write up their homework sets individually and to work the exams on their own. Class members may work on the homework sets in groups, but then each student must write up the answers separately. Students are not to copy homework or exam answers from another person's paper and present them as their own. Students who present other people's work as their own will receive at least a 0 on the assignment and may well receive an F or XF in the course depending upon the circumstances. Please see: Earth and Mineral Sciences Academic Integrity Policy: , which this course adopts.

Accommodations for students with disabilities:

Penn State welcomes students with disabilities into the University's educational programs. Every Penn State campus has an office for students with disabilities. The Office for Disability Services (ODS) Web site provides  contact information for every Penn State campus : . For further information, please visit the  Office for Disability Services Web site : .

In order to receive consideration for reasonable accommodations, you must contact the appropriate disability services office at the campus where you are officially enrolled,  participate in an intake interview, and provide documentation : . If the documentation supports your request for reasonable accommodations, your  campus’s disability services office  will provide you with an accommodation letter.

Campus emergencies, including weather delays

Campus emergencies, including weather delays, are announced on Penn State News: http:/ and communicated to cellphones, email, the Penn State Facebook page, and Twitter via PSUAlert ( Sign up at: ).

Course content

What a Practicing Meteorologist Needs to Know

  • Radiation and Matter 

The Big Picture (Sources of Radiation)
Repartitioning of Energy within Matter
Quantized Internal Energy States of Matter
Simple matter: Single lines with widths and strengths
Simple matter under increasing pressures: Changes in single line parameters
Complex matter: Multiple and merged lines forming continuum emission across all wavelengths
Planck Function Radiation
Probability of Energy States within Matter
The Planck Function

  • Integro-differential Form of the Radiative Transfer Equation 

Radiance (185-191)

  1. Power (185-186)

  2. Solid Angle (186-188)

  3. Definition of Radiance

  4. Invariance of (191-192)

Irradiance (206-211)
Connection to Radiance
Definition of Irradiance
Building the Radiative Transfer Equation
Attenuation/Extinction Term 

  1. Absorption and Scattering Coefficients (51-66, 60-66)

  2. From Coefficients to the Attenuation Term

  • Emission Term (4-15)
  1. Absorptivity and Emissivity [Kirchhoff's Law (14-15)]

  2. Planck Function: Temperature Dependent

  3. Emission Term: Planck Function and Absorptivity/Emissivity Dependent

  4. Scattering Term: Scattering Phase Function (293-295)

  • Heating Rates (58-59, 212)
  1. From Radiances to Irradiances

  2. From Irradiances to Heating Rates 

  • Multiple Scattering: Elementary (Section 5.2)
  1. Visualizing the Radiation Field
  • Some Nomenclature
  1. Optical Thickness (256)
  2. Mean Free Path (253-254)
  3. Single-scattering Albedo (254-257)
  4. Asymmetry Parameter (254-257)
  5. Brightness and Color Temperature (21)
  6. Wavenumbers (or Inverse Centimeters) (79)
  •  Properties of Matter: A First Look
  1. Building One's Intuition: Simple Sorts of Calculations
  • Properties of Matter
  1. Overview of Particle Concentrations and Cross Sections (91-94)
  2. Wavelength Dependence of Molecular Scattering (Fig. 2.12)
  3. Wavelength Dependence of Molecular Absorption (Fig. 2.12)
  4. Wavelength Dependence of (Spherical) Particle Scattering (Fig. 3.9, Fig. 3.11)
  5. Wavelength Dependence of (Spherical) Particle Absorption (Fig. 3.9) 
  • Multiple Scattering: The Full Monte (Chapter 6)

Digging Deeper into the Properties of Matter (The Why of Things)

To Cohere or Not to Cohere (or, Why Clouds are So Important to Climate)

  • Classical Electromagnetic Theory
  1. From Radiation as Energy Bundles to Radiation as Waves (129-134)
  2. Charges and Electric Fields
  3. Moving Charges and Magnetic Fields
  4. The Lorentz Force
  5. Maxwell's Equations (Yikes!)
  6. Response of Matter to Electric Fields
  7. Response of Matter to Magnetic Fields
  • Four Consequences of Maxwell's Equations
  1. Speed of Light
  2. Plane Electromagnetic Wave Solutions in Infinite Media (129-134, 141-142, 158-165)
  3. The Poynting Vector (Irradiance) (185-186)
  4. Production of Radiation by Accelerated Charges Dipoles
  • Why Matter Scatters and Absorbs Radiation the Way It Does
  1. Scattering and Absorbing Properties of Molecules
    Scattering by Air Molecules (128, 151-155)
  2. Scattering Phase Function of Molecules
    Absorption by Air Molecules (66-74, 76-84, 125-129)
    • Radiatively Active and Inactive Molecules (80-84)
    • State Populations and the Structure of Absorption (95-102)
    • Absorption Line Strengths, Shapes and Widths (102-105)
    Scattering and Absorbing Properties of Particles

Small Particles
Large Particles
Complex indices of refraction
Scattering by Spherical Water Particles (165-175)
Coherence Effects (134-141, 146-148, 148-151)
Small and Large Particle Limits (168-169, 169, 170-172, 172-175)
Absorption by Spherical Water Particles (110-115)
Small and Large Particle Limits