Preparatory Exercise #1
ATMS 111 – Understanding the Atmosphere (Lab)
The Sun
Due: 24 Aug 2015
In order to receive full credit for each correct response, you must show the steps taken to arrive at
the result.
(1) 240o = ________ radians
(2) cos(X) = 0.5, X = ________ radians
(3) M cos(Y) = M, Y = ________ radians
(4) tan(Z) = -1.7320508, Z = ________ radians
(5) Mike is six feet five inches tall, his shadow measures eight feet, what is the solar elevation
angle in radians? In degrees?
(6) The time is 3:45 pm Eastern Daylight Time (EDT). What is the time in decimal military time
(answer falls within the range 0.0 – 24.0 hours)?
(7) Sunrise is at 6:49 am EDT and sunset is at 8:20 pm EDT. Assume that solar noon is halfway
between sunrise and sunset. When is solar noon in decimal military time? When is solar noon
in Eastern Daylight Time?
(8) Sunrise is at 6:49 am EDT and sunset is at 8:20 pm EDT. At 11:00 am EDT you measure
Mike’s shadow to be 7.5 feet long, what will be the solar elevation angle [in radians] at solar
noon? Recall that Mike is six feet five inches tall. [Hint: use the expression; elevation angle =
A sin(Bt+C), where the given information helps you to determine constants “A”, “B”, and “C”.]
(9) At 11:00 am EDT, you note that the sun is directed toward the southeast (150o), what was its
azimuth angle [in radians] at sunrise (6:49 am EDT)? [Hint: use the expression; azimuth angle
= D cos(Et), where the given information helps you to determine constants “D” and “E”.] [Hint,
hint: recall that the azimuth angle at solar noon is always the same value, no matter the time
of year.]
(10) After examining Panel (c) from Fig 2.26 in the ATMS 113 textbook, what kind of change in the
azimuth angle at sunrise do you expect to find at Asheville as we move closer to December?
[a fun application related to “The Sun” http://www.esrl.noaa.gov/gmd/grad/solcalc/ ]