Agronomy 405/505
Spring 2011
Problem Set 2
Due Tuesday, January 25, 2011.
Assigned January 18, 2011.
1. Vist the Iowa Environmental Mesonet (http://mesonet.agron.iastate.edu) and
follow the following links to see the meteorological data collected at ISU meteorology instructor David Flory’s house: “Other” under “IEM Data Networks;” and then
“Mesonet Northeast Ames.” Look at the data for November 27, 2010 (the Saturday of
Thanksgiving weekend), and last Sunday, January 16, 2011.
You can download the raw data by clicking on “View raw data file.” The columns are
in this order: month; day; year; hour; minute; current outside air temperature (◦ F);
highest recorded air temperature so far that day (◦ F); lowest recorded air temperature
so far that day (◦ F); outside relative humidty (%); wind speed (mph); wind direction
(degrees); peak wind gust (mph); time of peak wind gust; air pressure (inches, adjusted
to sea level); precipitation so far that day (inches); precipitation so far that month
(inches); precipitation so far that season (inches); inside air temperature (◦ F); and
inside relative humidity (%).
Compare the air temperature data with the empirical model defined by Equations (2.2)
and (2.3) in Campbell and Norman (the class notes contain some minor corrections)
using flory_example.m, the example m-file, and flory20101127.dat, the data file.
(a) Produce a figure with two curves for November 27: the output of the empirical
model defined by (2.2) and (2.3); and the actual data.
(b) Does the model match the data for November 27? Explain.
(c) Produce a figure with two curves for January 16: the output of the empirical
model defined by (2.2) and (2.3); and the actual data. Now you will need to
modify flory_example.m and create your own data file from the information on
the IEM. Be careful to remove from your data file (using a text editor) any data
that is recorded near or after midnight.
(d) Does the model match the data for January 16? Explain.
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2. The dominant term of the dimensionless fluctuation (2.2) in Campbell and Norman is
sin (ωt + 0.9)
(1)
but the sinusoid in (2.4) of Campbell and Norman is written
sin [ω (t − 8)]
(2)
when z = 0. Rewrite (1) using the form of (2), i.e. find l if (1) is written sin [ω (t − l)]
and ω = π/12 rad hour−1 . Does the value of l make sense? Why or why not?
3. 2.1 in Campbell and Norman. Look at m–files for Example 2.1 and 2.2 on the course
website for guidance.
4. 2.2 in Campbell and Norman. Is this a moist or dry soil?
5. 2.4 in Campbell and Norman. Use the data file provided on the course web site so that
you don’t have to enter all the data by hand. Look at the example m–file interest.m
for help. I’d like you to try to solve this problem using MATLAB, but if you get stuck,
try using another tool like a spreadsheet application.
6. Read “Just Warm Enough” at http://ow.ly/3lSLo (also linked on the course website).
(a) Given the listed internal body temperatures of various mammals, where do humans lie? Do we have the highest body temperature or lowest or somewhere in
between?
(b) Where do we get the energy that is used to heat our body?
(c) Why is it advantageous to have a lower internal body temperature?
(d) According to the authors of the article published in the scientific journal mBio,
why could it be advantageous to have a high internal body temperature?
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