Insolation Investigation
Introduction
The sun’s angle of incidence to the earth’s surface varies
according to the time of day and the position of the earth
relative to the sun. One of the factors affecting an areas
climate is insolation. Insolation is the amount of solar
radiation (energy) received on earth’s surface. The equator
always receives 12 hours of solar radiation a day. For the rest
of the planet the amount is determined by the position of the
earth relative to the sun. (i.e. what time of year it is.) The
angle of incidence of solar radiation influences the amount of
heat absorbed by the planet, with a 90˚ angle having the
highest insolation.
Insolation measures the amount of sun’s energy the surface of the earth receives per unit of area. In terms of
global climate, the absorbed energy is what causes an increase in surface temperature. When the sun is not
directly overhead and the sun’s rays hit the planet at an angle, the energy is distributed over a larger surface area,
thus reducing the intensity of insolation.
Objectives and Hypothesis
In this investigation you will model the relationship between the angle of incidence and the temperature of a
surface by shining a light (the sun) on surfaces (the earth) that are at varying angles to the light source and
measuring the temperature of the surface.
In the space below, create a hypothesis that answers the following experimental question, “How does the angle of light
affect the temperature on a surface?”
Materials (per group)
 Protractor
 Ruler


Pieces of Cardboard
Tape


Thermometer
Lamp with 100 W bulb
Procedure
Design an experiment to test your hypothesis and answer the experimental question, “How does the angle of light
affect the temperature on a surface?” In the space below, record the procedure you will follow during your
experiment.
Data and Analysis
Use the space below to create a data table to accurately reflect the measurements you took during your investigation.
Use the graph paper to create a line graph showing the relationship (or lack thereof) between the variables you
tested.
Discussion
No formal discussion or error analysis is needed for this lab but you must answer the post lab questions below.
1. Discuss any trends you observed during your experiment with respect to the temperature and the angle of
the light.
2. Describe how earth’s tilt and its movement relative to the sun causes differences in insolation and the
seasons of the year.
The table below provides measurements for the insolation recorded for a city in Greenland (near the North Pole)
and in a city in Ecuador (near the equator). Consult the table and use data to support your answers to answer
questions 3-5.
Average Insolation (kWh /m2 / day)
Location
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
Qaanaaq,
0
0.02
0.48
1.78
3.75
5.15
4.91
2.95
1.16
0.12
0
0
Greenland
Quito
3.67
3.63
3.78
3.71
3.72
3.81
3.89
3.99
3.96
3.95
3.91
3.67
Ecuador
*NASA Langley Research Center Atmospheric Science Data Center; New et al. 2002
3. In Qaanaaq, Greenland, which three months of the year recorded an average insolation of zero? Explain
why there is no insolation recorded during these months?
4. Calculate the difference between the minimum and maximum average insolation measurements for both
cities for the year. (show your work for each including set up) What could account for this difference in
insolation variation throughout the year for these two cities?
5. According to the table, the average insolation recorded in May for the two cities is roughly the same.
However, the average temperature in May in Quito, Ecuador is 18˚C and in Qaanaaq, Greenland it is -11˚C.
Discuss possible reasons for the dramatic difference in temperature.
Specific Heat Investigation
Introduction
You may remember from previous chemistry or physics classes that the equation for specific heat is Q=cm∆T,
where Q is the amount of energy added, c is the specific heat, m is the mass and ∆T is the change in temperature. In
this investigation, you will be comparing the specific heat of sand with that of water. Because the water and sand
will be heated with the same heat lamp and at the same distance, they will have the same input of heat (Q).
Therefore csms∆Ts = Q = cwsw∆Tw so csms∆Ts = cwsw∆Tw . This equation may be rearranged to solve for the specific
heat of the sand cs = (cwsw∆Tw) / (ms∆Ts), where cw = 4186 J/kg˚C
Objective and Hypothesis
In todays lab you will determine the specific heat of sand and compare it to that of water and then relate the
differences in specific heat for these materials to explain climatic differences between coastal areas and areas in
the interiors of continents.
Use the space below to write a hypothesis that answers the experimental question, “What is the specific heat of sand
compared to water and what implications does this have for the climate of coastal areas?”
Materials
 Desk lamp with 100 W
bulb


Beakers
Water


Sand
Thermometer
Procedure
1. Put water in one beaker and an equal mass of sand in second beaker. Record the masses of sand and water.
mwater = _____________________________ kg
msand = _______________________________ kg
2. Stir the water and take the temperature of both substances, making sure to only put the bulb of the
thermometer in the material. Record the initial temperatures of the sand and water samples.
Twater = ______________________________ ˚C
Tsand = ________________________________ ˚C
3. Position the heat lamp no more than 20 cm directly above both beakers and turn the lamp on. Take the
temperature of the water and the sand every minute for 15 minutes. Record the temperatures in the data
table on the next page.
4. Turn off the lamp and continue taking the temperature of the water and the sand every minute for another
15 minutes. Record the temperature in the data table on the next page.
Data and Analysis
1. On the attached graph paper, create a line graph that appropriately illustrates the measurements recorded in
the data table.
2. In the space below, calculate the specific heat of sand. (show your set up and all work)
Time
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Temperature (˚C)
Water
Sand
Time
Temperature (˚C)
Water
Sand
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Post Lab Questions
No formal discussion of results or error analysis is required for this lab, but you must answer the following post lab
questions.
1. Compare the specific heat of sand to the specific heat of water. What does this indicate about the rate that
these two substances will heat up and cool down?
2. In this experiment we used light colored, dry sand. How do you think your results would be different if we
used darker sand or wet sand? Explain your reasoning.
3. Based on your findings of specific heat for water and sand, how can the specific heat of substances such as
water and various soils be a factor in influencing regional climates?
The tables below show the monthly insolation data for San Diego and Dallas along with the monthly average high
temperatures and monthly average low temperatures for each city. Use this information to answer questions 4 – 8.
San Diego, CA (Latitude 32.7150° N)
Jan
Feb
Mar
Insolation
2.50
3.23
4.19
(kWh/m2/day)
Average
Monthly High
18.4
18.3
18.7
Temperature
(˚C)
Average
Monthly Low
9.4
10.4
11.8
Temperature
(˚C)
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
5.26
5.61
6.24
6.54
5.79
4.94
3.84
2.70
2.25
19.7
20.3
21.6
23.7
24.7
24.4
22.7
20.6
18.2
13.3
15.2
16.7
18.6
19.3
18.4
15.9
12
9.1
*NASA Langley Research Center Atmospheric Science Data Center; New et al. 2002
Dallas, TX (Latitude 32.7150° N)
Jan
Feb
Insolation
2.50
3.23
(kWh/m2/day)
Average
Monthly High
14.0
16.1
Temperature
(˚C)
Average
Monthly Low
-0.9
1.7
Temperature
(˚C)
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
4.19
5.26
5.61
6.24
6.54
5.79
4.94
3.84
2.70
2.25
20.6
24.9
28.7
32.9
34.8
35.8
31.8
26.4
20.2
14.4
5.8
10.6
15.7
19.6
21.6
21.8
17.9
11.1
5.9
0.1
*NASA Langley Research Center Atmospheric Science Data Center; New et al. 2002
4. For both of the cities:
a. On the attached graph paper create a line graph of the monthly high and low temperatures. Be sure
to provide x – and y-axes and a key.
b. Calculate the temperature difference between the month with the highest average temperature and
the month with the lowest average temperature.
c. The temperature difference for the month that demonstrates the largest difference between the
average high and average low temperature.
5. Utilizing your calculations from the previous question, along with the graphs you created, describe which
city experiences the most dramatic climatic variations throughout the year.
6. Discuss why the city you identified in the previous question would experience more frequent variances in
temperature throughout the year.