Atmospheric Environment Kameron Johnson Spring 2015 May 1, 2015

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Fightin Texas Aggie Urban Canyon Heat Island

As the human population continues to move into more urban areas, the local climate effects can

be altered by the materials used to build the city. The heat urban island is defined as the difference in

temperature between the urban and rural areas. “Urban Heat Islands are caused by development and

the changes in radiative and thermal properties of urban infrastructure as well as the impacts buildings

can have on the local micro-climate” (Reducing Urban Heat Islands pg.6). As manmade infrastructure

replaces natural vegetation, albedo and radiation absorption values change causing more heat to be

trapped and released slower in the urban areas. Other influential properties of UHI are thermal

emittance, the measure of a surface’s ability to shed heat or emit longwave radiation, and heat capacity:

materials ability to store heat “thermal property”. As humans continue to change the land into more

anthropogenic needs, will this continue to have a warming effect on the local climate? There is evidence

of UHI contributing to more frequent and intense heat waves.

In an attempt to identify the heat urban island Texas A&M University contributes to the local

climate. Dr. Schade’s Atmospheric Environment class took measurements on campus using a sling

psychrometer, which uses two mercury bulb thermometers recording the dry and wet air temperature

obtained by swinging the instrument in the air for 1-2 minutes. After recording the difference in

temperature between the wet and dry bulb, the instrument has temperature and humidity scales where

we estimated the relative humidity by comparing the difference between the wet and dry bulb

temperatures. The temperatures we record were then compared to the Easterwood Airport rural station

just outside of College Station.

Texas A&M Campus Temperatures vs Rural Temperatures

The first campus measurements we took was on Friday March 13, 2015 on the south-side of

campus next to Duncan Drill Field and by the Eller O&M and CSA building. The temperatures were

Atmospheric Environment Kameron Johnson Spring 2015 May 1, 2015

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measured at 1:00PM for the Duncan Drill Field locations and 1:25PM next to the two buildings and

surrounding area.

The temperatures for that day show a small effect for the

1:00PM measurements with a difference of 1 degree F. The second reading at 1:25PM is pretty much

the same as the rural readings except for a couple locations. Jeanette’s locations experienced a 2 degree

difference while Kameron, Michelle, Bridget, and Paul experienced a 1 degree difference. These

locations are on or near materials that trap infrared radiation leading to a slightly higher temperature

measurement. The second location shows a slight urban heat island effect due to IR trapping, a

temperature measurement shortly after sunset would in theory show a higher gradient difference

compared to the rural data.

The second and third experiments were testing A&M’s urban canyon effect on the temperatures

located on Ross Street running WSW to ENE. The experiments took place on April 8 and April 20

between 1 and 1:30PM and like before compared to the rural temperature measurements. The April 20

measurements included campus parking lots 47, 50, and 51.

13 March experiments; overcast day (1:00PM) (1:25PM)

student T dry T wet student T dry T wet location description

Michelle 62 60 Jeanette 65 63

Parking Lot 40c, S of Lindsey

Bldg.

Kameron 61 60 Steven 63 60 Park ing Lot 40d

Bridget 62 59 NA

South lawn, Simpson Drill

field

Steven 61 59 William 63 61 Throckmorton

Gunnar 62 59 Kameron 64 61

Alumni Center, N side

entrance steps

Matthew 61 59 Michelle 64 60 Old Jersey x Ayrshire

NA Matthew 63 61

Paul 61 59 Bridget 64 60 Brison Park

William 61 59 Sophia 63 60 SW coner of Bush x Dexter

Jeanette 62 61 Paul 64 61 Park ing Lot of St. Thomas

Avg 61 59 Avg 63 61

13-Mar Rural Temp

Time Degree C Degree F

1:00pm 17 62

1:30pm 17 63

Daily Avg 17 63

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The measurements on this day

actually showed a cooler temperature than the reading observed at Easterwood. This could be caused

by the wind coming from a more rural area instead of over an urban area reducing the amount of IR

heat being transported to the campus locations. I was the only one who recorded a warmer

temperature which can be explained because I was in the middle of the street and the sun poked out of

the clouds during the second measurement.

On this day, the sun was out and

the wind was coming out of the North which means it traveled over Bryan before reaching the A&M

campus. The class averaged 4 degrees warmer in the Aggie Urban Canyon the students with the higher

8 April experiments; mostly cloudy day (1:00PM) (1:05PM) (1:10PM)

student T dry T wet student T dry T wet student T dry T wet

William 80 74 William 81 74 William 81 74

Matthew M. 80 76 Matthew M. 81 76 Matthew M. 81 76

Jacob 80 75 Jacob 79 75 Jacob 79 75

Kristen 80 73 Kristen 80 73 Kristen 80 73

Kameron 79 75 Kameron 81 76 Kameron 82 76

Matthew B. 80 75 Matthew B. 81 76 Matthew B. 81 76

Bridget 80 74 Bridget 80 74 Bridget 80 75

Paul 79 74 Paul 80 75 Paul 81 76

Sophia 80 74 Sophia 79 74 Sophia 80 74

Gunnar 80 73 AVG 80 75 AVG 80 75

AVG 80 74

8-Apr Rural Temp Avg Wind Avg Radiation

Time Degree C Degree F (m/sec) (W/m2)

1:00PM 27 81 410 9

1:10PM 27 81 418 10

20 April experiments; mostly sunny day (12:55PM) student (1:20PM) student (1:25PM)

student T dry T wet Paul T dry T wet Paul T dry T wet Location

Kristen 70 58 William 72 64 William 72 64 Parking Lot

Kameron 76 65 Jeanette 70 62 Jeanette 70 62 47

Matthew B 71 64 Steven 78 63 Steven 75 63 50

Steven 66 58 Kameron 75 63 Kameron 71 63 51

Bridget 72 62 Bridget 78 62 Bridget 75 62

Jeanette 75 67 Matthew B. 73 66 Matthew B. 74 66

Paul 69 61 Matthew M 72 64 Matthew M 74 64

Matthew M 74 63 Kristen 75 65 Kristen 74 65

Sophia 72 62 Sophia 75 61 Sophia 75 61

AVG 72 62 Gunnar 76 62 Gunnar 74 62

AVG 74 63 AVG 71 61

20-Apr Rural Temp Avg Wind

Avg

Radiation

Temp Degree C Degree F (m/sec) (W/m2)

1:00PM 20 68 5 806

1:20PM 20 68 4 537

1:30PM 20 68 4 606

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temps measuring in the sun and the lower temps are in the shade. Infrared radiation trapping could also

be a potential heat producer for the campus climate adding more heat to the wind moving over the

campus at that time.

The second readings located in the campus parking lots shows a sweaty 6 degree higher

temperature compared to Easterwood, while the second temperature measurements were cut in half

being just 3 degrees warmer. All the students were located on either black asphalt or grey concrete

which are materials that absorb radiation storing more heat than natural vegetation. Steven recorded a

10 degree difference which is the most out of all the other students for that particular measurement

along with the days overall observations.

The data collected by the class of Dr. Schade show valuable information needed to identify the

warming effects Texas A&M has on the local climate. The temperature readings when compared show

that the campus has a 1-2 degree higher temperature than the surrounding rural areas. In the Aggie

Urban Canyon, the temperature is controlled by the amount of radiation that reaches the surface and

the direction of the wind blowing thru the campus. When the wind first travels over a rural area before

reaching campus, a smaller temperature difference is observed. However, if the sun is shinning bright

and the wind reaches Bryan first, a higher temperature reading will be observed. This is also the case

with the parking lot measurements, the higher amount of radiation that reaches the asphalt or concrete,

a more dramatic difference will be noticed.