}}MAKE A SKETCH OF THE PROBLEM SET UP WHENEVER POSSIBLE! Homework problems
are intended to help you master the course material. You are strongly encouraged
to work with others, but make your submitted homework a unique expression
of your knowledge of the material.
A more thorough discussion of this process is given in the course description.
Example 1 of an easy to read, clear homework page. (Nice handwriting with a pen, on one side of the page only).
Example 2 of a word-processed homework page.
ASSIGNMENT 7 due October 14th before class.
1. Do the problem discussed at the end of this presentation.
2. Problems 7.1, 7.2 (note: this is only the direct beam transmission; no diffuse radiation is considered), 7.10, 7.13.
ASSIGNMENT 6 due October 7th before class.
1. Students must go through these online tutorials on microwave active and passive remote sensing:
a). Microwave remote sensing Introduction, b). Applications, c). Advanced Applications.
2. Problems 6.12, 6.15, 6.28.
3. Climate sensitivity calculation. Use Eq. 6.35 for the radiative equilibrium surface temperature for this problem. Calculate the derivatives dTs/dasw and dTs/dalw and estimate their values. Comment on the relative impacts of changes in the short wave and long wave absorption in the atmosphere to surface temperature changes. What does this model predict for the surface temperature when the atmosphere becomes totally opaque with respect to IR radiation (alw=1)? Interpret these results.
ASSIGNMENT 5 due September 30th before class.
Problems 5.2, 5.5, 6.1, 6.2, 6.5
ASSIGNMENT 4 due September 23rd before class.
1. Download the latest compilation of the complex refractive index for ice from here, or locally from here. Then calculate and interpret the following:
a)
Absorption coefficient.
b) Penetration depth.
c) Reflection coefficient for normal incidence.
d) Reflection coefficient for 45 degree incidence (both polarizations and the average of them).
Hint: You might wish to solve this problem first and use its results, or just use complex variables in Excel or Fortran, etc.
e) Brewster angle.
Scholars can study these papers related to wave propagation in complex media:
Ray tracing, general theory, total internal reflection, quick discussion.
2. Derive an expression for the rainbow angle of a spherical particle as a function of the refractive index (assumed real only). You can do this by solving the condition db/dTheta = 0 (see figures 4.7 and 4.8.) Here b is the impact parameter equal to the sphere radius * sin(thetai). Use your solution to discuss features of the rainbow including for water (rain drops or cloud droplets) why we see color, and why the rainbow is bright. What condition on the refractive index must happen so that the rainbow angle is associated with exact backscattering?
Extra Credit: (due any time during the semester).
3. Repeat problem 1 for water (refractive index table , and fortran code for the same).
4. Repeat problem 2, though for ice and atmospheric halos and sun dogs.
ASSIGNMENT 3 due September 16th before class.
1. Do this Sunphotometer related problem.
2. Sunphotometer measurements.
You will also set up an account so you can more effectively use this atmospheric radiation transfer site.
To subscribe for this site, do the following:
1. Go to the webpage http://www.spectralcalc.com/spectralcalc.php.
2. Click on the subscribe link in the upper left corner, and then subscribe as a new user. Save your login name and password.
3. Email the company at this address, spectralcalc@gats-inc.com, and tell them the following in your message:
My name is _____.
I am a student at the University of Nevada Reno.
We have a university wide license for this site.
Please add my username __________ to the UNR site license so that I can fully access this site.
Thank you.
Reference Notes:
Solar Zenith Angle: You will need this for the Langley plot as discussed below.
(see this image for a visual definition, taken from this site that also discusses it).
When the sun is directly overhead the solar zenith angle is zero degrees.
You can use this convenient website to calculate the solar zenith angle for your location. It has UNR as one option in its coordinates.
To determine the solar zenith angle at any latitude, longitude, and time of day, first start with 1 finding your latitude and longitude. (You can use UNR's zip, 89557, or your own if you do measurements from elsewhere.) Then enter your coordinates and the time at this website, and get the cosine of the solar zenith angle.
Rayleigh Scattering Optical Depth: You will need this for the homework also.
Molecules in the atmosphere scatter light as dipole scatterers. The scattering amount is much stronger at shorter wavelengths than at longer wavelengths.
Table of values of Rayleigh Scattering Optical Depths for the atmosphere. Top of the atmosphere solar radiation.
Specific Deliverables:
1. On as many days as possible, days with minimal clouds, use the sun photometer every 10 minutes to measure the amount of sunlight using your sun photometer, especially early in the morning and later in the day when the solar zenith angle changes rapidly with time. A data table for your sun photometer observations is available as a PDF, or as a Word doc. Be sure to line up the inlet to the LED so that the sun comes straight in, using the bulls eye target. OF COURSE, DON'T LOOK DIRECTLY AT THE SUN! Find the maximum signal at each measurement time, and record this value. Write up your procedure for doing these measurements (as if it were a manual for another person to use in learning how to run the sun photometer). You may find a number of sites on the internet that also describe sun photometer measurements, for example this one.
2. Make a graph of the natural logarithm of the voltage measurements in part 2 on the y-axis, and the air mass on the horizontal axis (air mass is 1/cos(solar zenith angle).) Do this on several days and see if you can extrapolate backwards to get the solar constant on days when the atmospheric optical depth is constant all day. You can look up the amount of sunlight at the top of the atmosphere for the particular wavelength of your instrument and use this for an absolute calibration of your instrument. This graph is called a Langley plot (see site 1, site 2, site 3).
3. Derive a slope for the Langley plot in part 2, and compare the value of the slope you get with this table of values of the clear sky optical depth from Rayleigh Scattering by molecules in the atmosphere (no aerosols, clouds, or gaseous absorption). Do this for several days, and compare your results. Is it reasonable to conclude that one day is 'cleaner' than another based on sun photometer measurements?
ASSIGNMENT 2 due September 9th before class.
Problems 2.7, 2.8, 2.9, 2.10, 2.14, 2.20. Also, define and discuss actinic flux; why is it important?
ASSIGNMENT 1 due September 2nd before class.
Read chapters 1 and 2. Problems 1.1, 1.2, 2.1, 2.2 and 2.3. On problem 2.1, add a part d) as follows. 2.1 d) What is the wavelength of a microwave oven, and why is it that wavelength?
Return to the course description, syllabus for ATMS 749.
