NATS 1780 A (Summer 2017): Lab - Atmospheric Radiation (Version 1.0)
Purpose:
The purpose of this lab is to investigate radiation processes in Earth’s atmosphere.
Experiments:
1. Illustrate radiation incident upon an object, reflected by an object, and refracted by an
object.
a. Provide one or more photographs. (If you are unable to use your own
photograph(s), clearly indicate your source using a URL, for example.)
b. Sketch the ray diagram corresponding to your photograph(s). Your diagram
should identify objects , media and interfaces . Rays should be labelled
appropriately. (Figure 1 (below) provides a generic illustration of a ray diagram.)
c. Provide process-flow diagram(s) to account for 1(b).
2. Illustrate radiation being scattered by an object.
a. Provide a photograph of radiation being scattered by one of the following:
i. A CCN (or smaller) size aerosol.
ii. A cloud/fog-droplet size aerosol.
iii. A precipitation-size aerosol.
(If you are unable to use your own photographs, clearly indicate your source
using a URL, for example.)
b. Sketch the ray diagram corresponding to your photograph. Your diagram should
identify objects, media and interfaces. Rays should be labelled appropriately.
(Figure 1 (below) provides a generic illustration of a ray diagram.)
c. Provide the process-flow diagram to account for 2(b).
3. Using a reputable source (e.g., The Weather Network or EMOS ), screen capture (see,
e.g., Figure 2) the UV report for a full day at a location of interest.
a. At which time of day does data start appearing in the report?
b. At which time of day does data stop appearing in the report?
c. Why isn’t UV Index data available for 24 hours each and every day?
d. At which time of day does the UV Index reach its maximum value?
e. Is there a diurnal ‘rhythm’ to the UV Index data? If so, describe it briefly.
f. Suppose a 1000 m thick cloud persists for the entire day. Using Figure 3,
estimate the percentage of radiation reflected, transmitted and absorbed by this
cloud.
g. The Weather Network warns: “UV rays can cause sunburns, eye cataracts, skin
aging and skin cancer. The higher the UV Index number, the stronger the sun's
rays, and the greater the need to take precautions.” Which radiation processes
are of concern from skin-exposure perspective for humans?
© L. I. Lumb - Sharing prohibited. Violators subject to legal and/or academic consequences. 1Figure 1. Incident, reflected and transmitted radiation at a boundary between two media.
Figure 2(a). UV Index versus time-of-day (EDT) for Canadian postal code M3J 1P3 on June
16, 2013. (Source: The Weather Network.)
Note: This is an example of what you are expected to capture. This is not a figure you are
© L. I. Lumb - Sharing prohibited. Violators subject to legal and/or academic consequences. 2intended to use for answering Question 3.
Figure 2(b). Downwelling shortwave irradiance (W/m2, red curve) versus time-of-day (UTC) for
EMOS on September 21, 2015. (Source: EMOS.)
Note: Downwelling shortwave irradiance serves as a proxy for the UV Index.
Note: This is an example of what you are expected to capture. This is not a figure you are
intended to use for answering Question 3.
© L. I. Lumb - Sharing prohibited. Violators subject to legal and/or academic consequences. 3Figure 3. Radiative transfer as a function of cloud thickness.
Submit your lab online via Moodle.
Note: You are encouraged to work together on labs. However, your submission must be
original. Translation: Write up your final lab submissions independently using your own words.
Assessment: This is a pass/fail component of the course that accounts for 4% of your overall
grade. Completing at least 75% of the lab appropriately will result in a “Satisfactory” assessment
and a grade of 3 out of 4; an “Outstanding” assessment, and a grade of 4 out of 4, will be
awarded to those who completed at least 90% of the lab appropriately.
© L. I. Lumb - Sharing prohibited. Violators subject to legal and/or academic consequences. 4