Lab Six: Insolation and Temperature
This lab is designed to introduce you to the number of factors that influence temperature at Earth's surface.
First, we will begin by studying how the amount of insolation received at the Earth's surface varies from
place to place. The variation of insolation leads to variations in temperature. Other factors, such as, land-
water contrasts, ocean currents, and wind patterns and air masses also influence temperatures. In addition,
we will explore how altitude affects temperatures.
Objectives:
Measure surface variation in temperature
Construct a temperature graph
Calculate temperature range
Name
Part 1: Incoming Solar Radiation & Surface Variations
The amount of incoming solar radiation (insolation) varies by latitude and by season. Since the sun's energy is
our primary source of energy, this radiation imbalance leads to temperature differences. Why do we see this
variation in insolation received?
Atmospheric Obstruction- clouds, haze, etc.
** Both of these factors vary by latitude and by season
Insolation received depends on:
Angle of Incidence**- the angle at which the sun's rays hit the Earth's surface- direct vs oblique angles.
Day Length**- the amount of time the sun is above the horizon
Exercise 6.1:
Calculate average annual temperature
Identify global temperature patterns and to
explore the reasons for these patterns.
Calculate the Average Lapse Rate
Recap from Lab 5. Select the BOLD word that is correct.
1. Places closer to the equator have HIGHER or LOWER solar altitudes and MORE or LESS variation in
daylength.
2. Places closer to the poles have HIGHER or LOWER solar altitudes and MORE or LESS variation in
daylength.
Let's explore how surface variations affect the energy received.
Albedo- the ability of an object to reflect radiation
Low Albedo surfaces: asphalt, aged concrete, dark roof/paint, dark soil, dark rock, forests, grass
High Albedo surfaces: snow/ ice, new concrete, light roof/ paint, sand/desert
Select the BOLD word that is correct.
3. Light colored surfaces have a HIGHER or LOWER albedo, thus reflecting MORE or LESS energy.
4. Dark colored surfaces have a HIGHER or LOWER albedo, thus reflecting MORE or LESS energy.
1 5. Relating this to Earth, which of the following surfaces reflect more and which reflect less? Classify the
following locations as having a low or high albedo.
a. Antarctica (ice sheet)
b. Lava Flow in Hawaii (black)
c. Aged Concrete Sidewalk
d. Greek Village with white houses
Part 2: Annual Temperature Variations
Temperature - sensible heat (energy that you feel)
Air is heated from the ground up by outgoing longwave radiation emitted from the Earth, not by
incoming shortwave insolation.
There is a lag time between the Earth receiving the shortwave insolation and remitting the energy as
longwave radiation. Although insolation peaks at noon, net radiation (the difference between
incoming and outgoing energy) continues to be positive (i.e. there is a surplus of energy) until the early
afternoon, causing temperatures to rise. Net radiation is negative (i.e. there is a deficit of energy) from
early afternoon until sunrise, causing temperatures to cool down. This also happens on an annual basis-
think about the hottest month of the year compared to the month seeing the highest solar altitude.
There are two important measures of annual temperature. The first measure is the temperature range-
the difference in temperature between the warmest month and the coldest month. This value is a very
useful indicator of seasonality of temperature- the amount of temperature change over the year. The
second is annual average temperature, which we will look at in Part 3.
Maximum Temperature - Minimum Temperature
Temperature Range:
Exercise 6.2:
Use the temperature graphs at the end of the lab to complete this section.
1. Calculate the Temperature Range for the following locations. Note: the temperatures displayed on the
graphs are the average temperatures for each month. St. Louis has been completed for you.
St. Louis, MO
=
Fairbanks, Alaska
Lihue, HI
Warmest Month-
Average Temperature
78° F
Coldest Month-
Average Temperature
2. How does latitude affect temperature range?
30° F
Temperature Range
78° -30° 48°
2 3. How does latitude affect temperature?
Part 3: Coastal Versus Continental Locations
Land heats and cools faster than water for the following reasons:
LAND
Lower Specific heat
Immobile - prevents mixing
Less Evaporation
Radiation concentrated at surface
Specific Heat: Amount of energy needs to raise 1 gram of a substance 1 degree of Celsius.
Results: Continental locations experience greater seasonal extremes- hotter summers and colder
winters (larger temperature range).
Coastal locations experience more moderate, uniform temperatures (lower temperature
range).
Annual average temperature averages all high and low temperature values for a location over the
course of the year to give a single, coarse measure of temperature.
Average Annual Temperature = Sum of the temperatures/ Number of temperatures
Exercise 6.3:
Average Monthly Temperatures for 3 Cities:
San Francisco, CA-- 37.6°N, 122.4°W
Temperature
| (°F)
Temperature
(°F)
J
49
Wichita, Kansas-- 37.7°N, 97.4°W
J
7
30
Temperature
(°F)
52
J
39
F
33
Norfolk, Virginia-- 36.9°N, 76.2°W
M
53
F
41
M
44
M
49
A
56
A
56
A
57
M
58
M
65
M
66
J
61
WATER
Higher Specific Heat
Mobile- allows mixing
More Evaporation
Radiation penetrates below surface
J
74
J
74
J
63
J
80
J
78
A
64
A
79
A
77
S
64
S
70
S
72
O
61
O
58
O
61
N
55
N
44
N
52
D
49
D
34
D
44
1. Compute the Temperate Range and Average Annual Temperature for San Francisco, Wichita, and
Norfolk. Check Your answer using the Lab Six Temperature Data Excel file.
3 2. Construct a temperature graph by plotting the Average Monthly Temperatures on the Graph below or
by using Excel.
Use red to plot San Francisco, blue for Wichita, and green for Norfolk.
Annual Temperature Graph
°F
90
80
70
60
50
40
30
20
10
O
-10
J
F
M
A
M
J
J
A 'S
O
N
D
10°C(50°F)
5°C(41°F)
0°C(32°F)
-5°C(23°F)
3. Based on the data provided, describe the relationship between continental/coastal locations and
temperature range.
4. Why does San Francisco have a smaller temperature range than Norfolk, Virginia, even though both are
located on coasts? Keep in mind that the prevailing winds are from the west.
4 Part 4: Average Lapse Rate- change in temperature as a result in altitude change.
Average Lapse Rate: 3.6° F/ 1000 feet or 6.5° C/ 1000 meters
Steps for calculating the Lapse Rate
Example: If the temperature is 93.6° F at 1000 feet, what would the temperature be like at 5000 feet?
Step 1: Find the Elevation Difference: Maximum – Minimum
5000-1000 = 4000 feet
Step 2: Set up equivalent fractions and cross multiply:
(Temp)
3.6° F
X
(Elevation)
1000 ft
4000 ft
=
(4000* 3.6)/1000 = 14.4° F
Step 3: If calculating for a higher elevation, subtract degrees from starting temperature. If calculating
for a low elevation, add degrees to starting temperature.
93.6° F 14.4° F = 79.2° F at 5000 ft
Exercise 6.4:
Calculate the temperature using the average lapse rate for the locations listed below. Round your answers to
one decimal place.
1. Currently the temperature is 99° F in San Bernardino (elevation 1200 ft). Using the ALR, calculate the
temperature in Big Bear Lake (elevation 6,752 ft) and San Gorgonio Peak (elevation 11,499 ft). You may
want to sketch a diagram to help you visualize the problem.
2. Looking at the temperature graph for Lihue (elevation 103 ft) and Kilauea (elevation 1134 ft). Does the
environmental lapse rate explain the temperature differences between these two locations? Explain
your reasoning.
5/n
