Practical 02 Submission Form (GGR112 Fall 2023)
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University of Toronto, Mississauga *
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112
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Geography
Date
Dec 6, 2023
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GGR112 | Fall 2023
Lab 2
Student name:
Shahmeer Imran
1.
After returning indoors, provide your group’s data to your TA. Your TA will calculate the average values
for the class as a whole. Copy the
class-average
values in Table 2 below. Do not enter your individual
group’s data in the table.
(1 mark)
Table 2.
Class-averaged values of air temperature, wind speed, cloud cover, shortwave up/down, radiated
up/down temperature, and longwave up/down.
Site
Air temp
(°C)
Wind
Speed
(km/h)
Cloud
Cover (0-9)
K↑
(W m
∙
2
)
K↓
(W m
∙
2
)
Radiated
T
surface
L↑
(°C)
Radiated
T
sky
L↓
(°C)
L↑
(W m
∙
2
)
L↓
(W m
∙
2
)
Urban
25.3125
5.72375
2
125
464
33.0
-7.725
473
169
Suburban
24.95
3.51875
1
87
429
32.2
-9.2875
468
165
Rural
26.575
3.08875
1
112
387
27.9
-9.75
442
164
2.
Provide the time of day and surface description for each site in Table 3 below.
(1 mark)
Table 3.
Sampling time and surface description.
Site
Time of sampling
Description of surface materials
Urban 1
1:20 PM
Concrete
Suburban 1
1:35 PM
Grass
Rural 1
1:50 PM
Grass
3.
Using the data from Table 2 and the relevant equations provided above, calculate net radiation and
surface albedo for each site type and enter these values in Table 4 below
(2 marks).
Table 4.
Calculated net radiation and albedo
Site
Q*
(W/m
2
)
Albedo (α)
Urban 1
35
0.26939
Suburban 1
39
0.20279
Rural 1
3
0.28941
4.
Based on the field data you collected, examine the mean albedo values for the three site types (
2
marks
)
0.25386
a.
Which surface was most reflective to shortwave radiation? Which was least reflective?
The surface that was the most reflective to shortwave radiation was urban. Suburban was the least.
1
GGR112 | Fall 2023
Lab 2
b.
Do the calculated albedo values conform to theoretical range of values in Figure 2?
The values do essentially conform into the theoretical range. However, the value for rural was slightly above
the theoretical solar reflectance of grass.
5.
Did the radiated sky temperature fluctuate substantially between sites? Discuss why it was or wasn’t
variable? What are you measuring when you point the infrared thermometer toward the sky?
(2
marks)
The radiated sky temperature didn’t fluctuate much between sites. For the grass sites it stayed between
the range of -9, while it was -7.7 for the concrete site (urban). It makes sense that it didn’t fluctuate
much because the total incoming long-wave radiation was fairly consistent at all sites, as there was
minimal cloud coverage. When you point the infrared thermometer towards the sky you are measuring
the total incoming long-wave radiation.
6.
Which surfaces had the lowest and highest emission of long-wave radiation (L↑) and what properties
of these materials account for this disparity?
(2 marks)
The urban surfaces have the highest emission of long-wave radiation, while the rural site has the lowest
emission. The urban surfaces were all concrete (higher solar reflectance), while the rural surfaces were
grass (lower solar reflectance).
The concrete emitted the highest long-wave radiation because it is
worse at absorbing the radiation, as compared to the grass.
7.
Do the measured air temperatures support the presence of an urban heat island at the ‘urban’ sites on
campus? What factors contributed to the elevated temperatures at the urban sites? If not, what factors
do you think mitigated the phenomenon on the day of the data collection?
(3 marks)
The measured air temperatures do indicate the presence of an urban heat island at the 'urban' sites on
campus, with an average air temperature of 25.3125°C, which is slightly higher than the suburban (24.95°C)
and the rural (26.575°C) sites. A factor is the increased absorption of shortwave solar radiation (K↓), which
is seen to be higher at the urban site (464 W
m²), as compared to the suburban (429 W
m²) and rural sites
∙
∙
(387 W
m²). Concrete and asphalt at the urban site can absorb more solar radiation during the day and re-
∙
emit it as heat, raising the temperature. Furthermore, the urban site had a higher wind speed (5.72375
km/h), which could have caused more mixing of air masses, which could lead to a higher average
temperature.
8.
How could wind speed influence heat loss in the different environments, and do you believe wind had
an appreciable influence on the dataset?
Explain your answer.
(1 mark)
The speed of the wind may have a considerable influence on how heat is lost in certain locations. It can
facilitate heat transmission via convection, resulting in greater surface cooling. The data shows that the
urban environment had greater wind speeds at 5.72 km/h, while the suburban and rural environments had
lower wind speeds at 3.51 km/h and 3.09 km/h, respectively. Due to this, increased convection may cause
2
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