1 GEOG 1112 Lab 4 Insolation and Net Radiation Due: 11:59pm, Sept. 12, 2015 Please type your answers in Word, and print out the blank graphs, and draw the graphs by hand, and then scan the completed graphs (or take pictures of your answers if you don’t have a scanner) as images. And then insert the images into the Word file. Submit it to the folder of Lab 4 in the Dropbox on the homepage of the course on D2L in the following format: If Mary Smith is submitting lab 4, please name the file as MarySmith_lab4.doc. Purpose The purpose of this lab is for you to understand annual cycle of insolation and daily cycle of net radiation. Background Insolation is the amount of solar radiation that reaches the earth surface. The annual cycle of insolation at a given location on the globe depends on two factors: (a) the latitude at which the observer is located and (b) the sun’s changing angle above the horizon at noon, which is caused by the movement of subsolar point. Net radiation is the difference between incoming and outgoing flows of solar radiation. The daily cycles of net radiation at a given location on the global depends on the changing incoming and outgoing flows of radiation in the course of a day. It is called radiation surplus when incoming radiation is larger than outgoing; It is radiation deficit when outgoing larger than incoming. Air temperature change is associated with the change in net radiation. Assignment 1 The Annual Cycle of Insolation (1) Table 1 gives the latitude of the subsolar point at ten-day intervals throughout the year. Plot theses points on the blank graph (A) and connect them with a smooth curve. (10 points) (2) Table 2 gives the intensity of insolation at various latitudes throughout the year. Plot these monthly values for the following latitudes: 0°, 20°N, 40°S, 60°N, 90°N on the blank graph (B). Enter the data point in the middle of the month as shown on the partially drawn line for 60°N. Connect the points with a smooth curve and label the latitude. (20 points) 2 Table 1 The latitude of subsolar point throughout the year Table 2 Insolation throughout the Year (one unit is 889 gram calories per square centimeter) Date Subsolar Point Date Subsolar Point 3 S u b so la r P o in t 4 (3) Study the insolation curves in relation to the annual curve of the subsolar point. Compare times of maximum and minimum values at 60°N and 40°S. Explain how these two curves differ in timing. (10 points) (4) Explain how the maximum and minimum of insolation at the equator are related to the curve of the subsolar point. (10 points) (5) Compare the insolation curves of 20°N and 90°N. Explain how these two curves differ in timing. (10 points) su b so la r p o in t 5 2 The Daily Cycle of Net Radiation (1) Table 3 gives the net radiation at the ground and air temperat ...

1. 1
GEOG 1112
Lab 4 Insolation and Net Radiation
Due: 11:59pm, Sept. 12, 2015
Please type your answers in Word, and print out the blank
graphs, and draw the graphs by
hand, and then scan the completed graphs (or take pictures of
your answers if you don’t have
a scanner) as images. And then insert the images into the Word
file. Submit it to the folder of
Lab 4 in the Dropbox on the homepage of the course on D2L in
the following format:
If Mary Smith is submitting lab 4, please name the file as
MarySmith_lab4.doc.
Purpose
The purpose of this lab is for you to understand annual cycle
of insolation and daily cycle of
net radiation.

2. Background
Insolation is the amount of solar radiation that reaches the earth
surface. The annual cycle of
insolation at a given location on the globe depends on two
factors: (a) the latitude at which the
observer is located and (b) the sun’s changing angle above the
horizon at noon, which is caused
by the movement of subsolar point.
Net radiation is the difference between incoming and outgoing
flows of solar radiation. The
daily cycles of net radiation at a given location on the global
depends on the changing incoming
and outgoing flows of radiation in the course of a day. It is
called radiation surplus when
incoming radiation is larger than outgoing; It is radiation deficit
when outgoing larger than
incoming. Air temperature change is associated with the change
in net radiation.
Assignment
1 The Annual Cycle of Insolation
(1) Table 1 gives the latitude of the subsolar point at ten-day
intervals throughout the year. Plot

3. theses points on the blank graph (A) and connect them with a
smooth curve. (10 points)
(2) Table 2 gives the intensity of insolation at various
latitudes throughout the year. Plot these
monthly values for the following latitudes: 0°, 20°N, 40°S,
60°N, 90°N on the blank graph
(B). Enter the data point in the middle of the month as shown on
the partially drawn line for
60°N. Connect the points with a smooth curve and label the
latitude. (20 points)
2
Table 1 The latitude of subsolar point throughout the year
Table 2 Insolation throughout the Year (one unit is 889 gram
calories per square
centimeter)
Date Subsolar Point Date Subsolar Point
3

4. S
u
b
so
la
r
P
o
in
t
4
(3) Study the insolation curves in relation to the annual curve of
the subsolar point.
Compare times of maximum and minimum values at 60°N and
40°S. Explain how these two
curves differ in timing. (10 points)
(4) Explain how the maximum and minimum of insolation at
the equator are related to the

5. curve of the subsolar point. (10 points)
(5) Compare the insolation curves of 20°N and 90°N. Explain
how these two curves differ
in timing. (10 points)
su
b
so
la
r
p
o
in
t
5

6. 2 The Daily Cycle of Net Radiation
(1) Table 3 gives the net radiation at the ground and air
temperature for a station in the
Midwestern US at about latitude 40°N on a day in mid-August.
Sunrise occurred at 5:15am;
sunset about 6:50pm local time. Plot the data points on the
blank graph C and connect them
with smooth curves. Use the upper graph for net radiation; use
the lower graph for air
temperature. (20 points)
Table 3 Net radiation and air temperature for a station
(2) Please label the areas of radiation deficit and surplus on the
upper graph
Estimate the time at which deficit changed to surplus:
.
Estimate the time at which surplus changed to deficit:
. (10 points)
(3) Estimate the time of occurrence of minimum temperature
from the lower graph: .
Explain the time of minimum temperature in terms of net
radiation curve. (5 points)

7. (4) Estimate the time of occurrence of maximum temperature
from the lower graph: .
Explain the time of maximum temperature in terms of net
radiation curve. (5 points)
14
6
Graph C