lab 4
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University of Illinois, Urbana Champaign *
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120
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Industrial Engineering
Date
Dec 6, 2023
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6
Uploaded by ProfessorFlowerLoris27
ATMS 120: Fall 2023
© 2023 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign
1
Name and NetID: Abby Pritz
Lab #4: Tropical Cyclones
Due Tuesday, September 26th, at 11:59PM
Part #1 Evacuating Fort Myers (5 points)
Evacuation for Hurricane Ian could be considered quite messy. Fort Myers, Florida ordered a mandatory evacuation
less than 24 hours ahead of Hurricane Ian’s landfall. There are a lot of logistics to consider when deciding evacuation
orders. Let’s look at the situation mathematically and see how long it would take to evacuate the Fort Myers area
if
everything ran smoothly
(i.e., people were prepared and there were no accidents blocking roads, etc.). Using the
information below, calculate how long
(in hours)
it would take to evacuate all 92,500 people from the Fort Myers
area. (Show all your work!)
92,500/2.3=40,217.3913
40,217.3913/18=2,234.3
3.5(2,234.3)=7,820.05 seconds
7,820.05/60=130.33 minutes
130.33/60=
2.172 hours
Assumptions:
Assume all the people evacuate by car and that each car carries an average of 2.3 people
Assume that all cars evacuate using major roadways (Interstates, expressways, highways) and that there are a total of
18 outbound lanes leaving the Fort Myers area
The rate of cars exiting the metro area is 1 car per 3.5 seconds per lane.
Part #2 Hurricane Maria’s eyewall speed (5 points)
After Hurricane Maria hit Dominica, it moved into the Caribbean and began tracking toward Puerto Rico. At the time
this satellite image was created, a weather station on St. Kitts and Nevis measured a wind speed of 25 mph. This
weather station was 70 miles from the center of Maria’s eye. The diameter of Maria’s eye was measured at 23 miles.
Use this information to solve for the wind speed at this time in Maria’s eye wall. Use this wind speed to find the
Hurricane Maria’s rank on the Saffir-Simpson scale when this image was taken. There is an excellent example of how
to solve this on Fig. 24.22 on page 505 (Show all your work!).
ATMS 120: Fall 2023
© 2023 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign
2
25x(70/(23/2))=152.174 mph wind speed
Because the wind speed of hurricane Maria’s eye wall is 152.174, she would be categorized as a category 4 hurricane.
Part #3 (5 points; 1 point each, 2 points for #4)
Imagine it is early November 2027, and the 7th named tropical cyclone just formed in the Caribbean and is forecast
to move toward Florida. Answer the following questions.
1.
Would you consider the 2027 hurricane season to be
above average, average,
or
below average
in terms
of hurricane activity?
The 2027 hurricane season would be above average, because each season has an avg. of 7 hurricanes, and
the season ends Dec 1. This would mean that the 2027 hurricane season would already have had the avg.
number of hurricanes a month before the season ends.
2.
If this tropical cyclone were to achieve a maximum sustained wind speed of 117 mph, where would it rank
on the Saffir-Simpson Scale?
At 117 mph, the cyclone would rank at category 3.
3.
What would its name be?
Its name would be Grace.
4.
Examine the map below, which has two arrows that show two possible tracks for the eye of this hurricane.
Which hurricane track (#1 or #2) would produce the worst possible situation for Tampa, FL, in terms of
storm surge and wind damage? Please explain why in one or two sentences. (Tampa’s distance from both
tracks is exactly the same.)
Hurricane track #1 would produce the worst possible situation for Tampa, FL, in terms of storm surge
and wind damage. This is because, on this track, Tampa would be on the rightward side of the eye,
bringing stronger winds and more storm surge.
ATMS 120: Fall 2023
© 2023 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign
3
Part #4 Pressure vs. Wind (4 points; 1 point each, 2 points for #3)
The Figure below represents the observed relationship between the air pressure measured at the center of circulation
and the maximum sustained winds for all tropical cyclones in the Atlantic Ocean from 1979-2015. Answer the
following questions. (
NOTE: the winds speeds are given in knots, not mph and 1 hPa = 1 mb.
)
1.
Hurricane Idalia (2023) was a Category 4 hurricane on the Saffir-Simpson scale and hit Florida with
maximum sustained winds of 130 mph. Use the graph below to estimate Idalia’s minimum pressure at
landfall.
Idalia’s minimum pressure at landfall is about 930 hPa.
2.
Hurricane Lee’s (2023) pressure bottomed out at 920 mb. According to the chart, what was Lee’s wind
speed (in knots) when its pressure fell to 920 mb? What rank on the Saffir-Simpson scale did Sam achieve
when its pressure was at 920 mb?
When Lee’s pressure fell to 920 mb, its wind speed was about 140 knots.
3.
The color shading on this graph represents the number of tropical cyclones at each wind and pressure
interval that were used to create this plot. Based on the shading on this graph, are strong hurricanes or weak
hurricanes more common?
According to the chart, weak hurricanes are more common, as there is much more yellow and orange
shading than the darker colors.
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ATMS 120: Fall 2023
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4
Part #5 Coriolis Effect (6 points; 4 points for calculation, 2 points for question)
We learned that the reason hurricanes rotate is due to a balance of two forces – the Coriolis force and the pressure
gradient force. Rather than performing calculating the Coriolis force on a hurricane, let’s see how much the rotation
of the earth impacts the flight path of a game-winning Hail Mary touchdown pass for the Illini at Memorial Stadium.
The equation below represents the east-west deflection due to the Coriolis force for objects that are moving south to
north. Assume that the football was thrown a distance of 50 m in the air.
Show all of your work!
∆࠵? = ࠵?࠵?
!
࠵?
"
sin ࠵?
Ω
= angular velocity of the Earth =
=
7.292*10
-5
1/sec
v
0
= south-to-north velocity of the football =
20 m/s
t
= total time of travel for the ball =
2.5 seconds
࠵?
= latitude (keep in degrees) =
40°N
Δx
= east-west deflection (meters)
2
π
86164
s
ATMS 120: Fall 2023
© 2023 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign
5
∆࠵?
=(7.292x10^(-5))(20)(2.5^2)(sin40)
∆࠵?
=
0.0058590090621 m
If a football pass is thrown off target such that it is intercepted by the opposing team, is the Coriolis force to blame
for this? Briefly discuss
(2 points)
.
If a football is thrown off target such that it is intercepted by the opposing team, the Coriolis force is not to
blame, because the Coriolis force will only cause 0.0059 meters, or ~0.016 feet, which is not enough for a ball
to be thrown off target so much.
Part #6: Graphing Hurricane Ian’s Winds and Pressure (10 points; 4 points for the graph, 2 points per question)
Hurricane Ian was a powerful Category 4 hurricane that made landfall in southwestern Florida in 2022. Hurricane
strength is categorized using the Saffir-Simpson Scale, which ranks hurricanes based upon sustained wind speed.
We have learned that wind is a result of a change in air pressure (i.e., the pressure gradient). Let’s use this idea to
analyze data taken from Hurricane Ian.
The Excel file is under Lab #4 on Canvas.
Column A: Date of the observation
Column B: Time of the observation
Column C: Sustained Wind Speed (knots)
Column D: Wind Direction (deg)
Column E: Wind Gust Speed (knots)
Column F: Wind Speed (mph)
Column G: Pressure (mb)
There are no data in column E and no data in columns D after 3:48 PM on 9/28/22.
Please complete the following tasks:
1.
Calculate the wind speed in mph (miles per hour) in column F using the data in Column C. 1 knot = 1.15
mph
2.
Create a graph of the wind gust speed and pressure as a function of the time (column B). Please graph the
entire data set even though there are no pressure data after 3:48 on 9/28. Set the primary y-axis values to
wind speed and the secondary y-axis to pressure (just like the example Figure below). Please turn in a
screenshot of your graph including the answer to the questions below.
Place your name on your graph
like I have below.
ATMS 120: Fall 2023
© 2023 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign
6
Questions:
1.
What relationship do you see between the pressure line and the wind speed line on your graph? (Hint:
Remember that pressure gradients, not low pressure itself creates strong winds.)
As the wind speed increases, the pressure appears to decrease, ending at one of wind speed’s peaks.
2.
Look at your wind speed line. Why is there a drop in the center? (Hint: Remember that pressure gradients,
not low pressure itself creates strong winds.) Why is one side higher than the other?
There is a drop at the center because it reaches the eye of the storm, which has a lower pressure and wind
speed. The wind speed picks back up as it leaves the eye.
3.
Please draw on your graph (or else sketch below) what you think the rest of the pressure line would have
looked like if I provided the whole dataset?
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