Lab 6 hail Carly Hoover - ATMS 120 Lab 6 PDF

Preview

Summary

ATMS 120 Lab 6...

Description

ATMS 120 Winter 2021

Name and NetID:_____Carly Hoover__ Carlygh2_________________

Lab #6: Mesoscale Convective Systems, Supercells, Hail and Tornadoes 75 points. Remember to turn in a picture of your iCard along with your submission. Part #1 – Wind Shear 10 points total Strong wind shear is a crucial ingredient for severe thunderstorm development. Wind shear is defined as the change in wind speed and direction with height. Supercell thunderstorms form most frequently on the Great Plains of the central US. The most common supercell wind profile exhibits southeasterly winds at the surface that strengthen and become westerly with altitude. The most common wind profile for a squall line (a.k.a. mesoscale convective system) is unidirectional, meaning that the wind speeds increase with height but the direction of the wind does not change with height. Five different wind profiles are below. Place a triangle around the letter beneath the most common supercell wind profile and place a circle around the letter beneath the most common MCS wind profile (2 point each).

Bulk wind shear is calculated by finding the vector difference between the winds at two different heights. Using the supercell wind profile you identified, calculate the 0-1 km and 0-6 km bulk wind shear values. This means we will find the difference between the surface wind (lowest wind barb on the sounding) and the speed of the wind at 1 km and 6 km. The atmospheric pressure at 1 km above sea level is typically very close to 850 mb. The pressure at 6 km above sea level is very close to 500 mb. Please calculate the 0-1 km and 0-6 km wind shear values in knots (kts). For simplicity, assume that the surface winds are due southeasterly, the 850 mb winds are due southerly, and the 500 mb winds are due westerly. Show your work. (3 points each)

© 2020 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign

1

ATMS 120 Winter 2021

0-1 km shear value ____30 kts_____ 1 km wind shear – 0 km wind shear 45 kts – 15 kts = 30 kts 0-6 km shear value ____55 kts_____ 6 km – 0 km 70kts – 15 kts = 55 kts Part #2 Questions about Severe Storms 18 points total 1.

Which type of thunderstorm is the largest in terms of size and area covered? Ordinary Thunderstorm, Mesoscale Convective System (MCS, squall line), or Supercell Thunderstorm a. MCS

2.

If a shelf cloud from an MCS were to pass over you, how does the temperature and wind speed change? a. Temp begins to cool and wind speed picks up

3.

What is the most frequent type of damaging severe weather from thunderstorms? Straight Line Winds, Hail, or Tornadoes a. Straight Line winds

4.

Label the clouds types pictured below (indicated with arrows). a. ___wall cloud________ b. ___Anvil cloud_______ c. __mammatus cloud____ d. __shelf cloud_________ e. ____overshooting top__

5.

Where do tornado fatalities rank in terms of deadliest forms of weather in the last 10 years? a. #3

6.

Which is more threatening to life and property for the region in which it is issued – a severe thunderstorm watch or severe thunderstorm warning? a. Warning because it means a severe storm has been spotted and is happening currently

7.

Is Chicago, IL in tornado alley? a. yes

8.

List 4 problems with using the Fujita Scale to rank tornado strength. a. Subjective assessment b. Non-uniform construction standards c. If tornado hits nothing, it can be rated lower than max intensity d. Only know the strength after damage survey

© 2020 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign

2

ATMS 120 Winter 2021

9.

“Weak” tornadoes account for __85_% of all tornado reports and _5_% of all tornado fatalities. “Violent” tornadoes account for __2_% of all tornado reports and _70_% of all tornado fatalities.

10. If a large, violent tornado is approaching your location and you are on an open roadway (with no strong or sturdy buildings nearby), what is the safest course of action? a. Get out of car and find an area lower than the level of the roadway. The easiest would be a ditch and lie as low as possible while covering your head. Bridges and overpasses are not safe places to hide

Part #3 Hail Damage 15 points The 2nd largest hailstone every measured fell in Aurora, Nebraska, in 2003. The circumference of that hailstone was 16 inches. Using the circumference and the information below, answer the following questions. Show your work. What you need to know… Ø Kinetic Energy = 0.5 * Mass * Velocity2 (Units: Mass à kg, Velocity à m/s, yielding Joules J) Ø Density of the ice in the hail stones = 31 lbs/ft3 Ø The volume of a sphere is (4/3) × π × r3 Ø The fall velocity of a hailstone in still air can be approximated using the equation V = k d where k = 20 if d (the diameter of the stone) is given in centimeters. V will have units of meters per second (m/s) as long as d is in cm. Ø Density = Mass/Volume Ø Assume the hailstone was spherical What was the diameter of the hailstone in inches? _~5 in____ 16=pi(d) = 16/pi = d = ~5 in

What was the volume of the hailstone in cubic inches? _____ 𝟒 𝑽 = 𝝅𝒓𝟑 𝟑 V = (4/3)pi(2.5)^3 V = 65.44 in^3 What was the fall velocity of this hailstone in m/s? ______ 𝑽 = 𝟐𝟎( √𝟏𝟐. 𝟕𝒄𝒎) V = 71.27 m/s What was the total mass of the hailstone in kg? _____ 31 = M/65.44 M = .51 kg What was the total kinetic energy of this hailstone in Joules? _______ K = .5(.51)(71.27^2) K = 1295.25 J

© 2020 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign

3

ATMS 120 Winter 2021

Part #4: 2017 Hail Data 10 points total Download the US hail reports for 2019 from January through June from Moodle. Using these data complete the following tasks. For help, check out this video https://www.youtube.com/watch?v=8V3ny_7IvfQ 1. 2. 3. 4. 5. 6. 7. 8.

How many people were injured in this period of 2019 by hail (1 pt)? 1 How many people were killed by hail in this period of 2019 (1 pt)? 0 What was the total economic loss of all hail events combined in this period of 2019 (1 pt)? 170003020 What is the total number of hail reports in this period of 2019 (1 pt)? 5636 Create a bar graph that shows the hail reports for each day of the year through June (2 pts). Create a line graph that shows the cumulative hail reports throughout this period of 2019(2 pts). Which day had the most hail reports in this period of 2019 (1 pt)? June 1 What was the largest hailstone diameter in this period of 2019 and in which state(s) did it fall (1 pt)? 5.5 in – Texas

Hail%Reports%- June%2019 250 200 150 100 50

6/1/19 6/2/19 6/3/19 6/4/19 6/5/19 6/6/19 6/7/19 6/8/19 6/9/19 6/10/19 6/11/19 6/12/19 6/13/19 6/14/19 6/15/19 6/16/19 6/17/19 6/18/19 6/19/19 6/20/19 6/21/19 6/22/19 6/23/19 6/24/19 6/25/19 6/26/19 6/27/19 6/28/19 6/29/19 6/30/19

0

Cumulative%Hail%Reports%- June%2019 2500 2000 1500 1000 500 0 7/2/ 7/1/ 6/30 6/29 6/28 6/27 6/26 6/25 6/24 6/23 6/22 6/21 6/20 6/19 6/18 6/17 6/16 6/15 6/14 6/13 6/12 6/11 6/10 6/9/ 6/8/ 6/7/ 6/6/ 6/5/ 6/4/ 6/3/ 6/2/ 6/1/ 5/31 5/30

© 2020 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign

4

ATMS 120 Winter 2021

Part #5: Wind Force on a Tree 8 points In one of your instructor’s neighbor’s backyards is a huge pin oak tree. How fast would the wind need to be in a thunderstorm to uproot this tree and knock it over? The force required to uproot this tree is approximately 640,000 N (640,000 kg m/s2). How fast would the wind have to be (in mph) to generate this force against this tree? Use this information below to solve this problem. Show all of your work and be careful with units!

!ρC A $ F = # D & v2 " 2 % F = Force applied by the wind = 640000 kg m/s2 ρ = Air Density = 1.22 kg/m3 CD = Drag Coefficient = 0.78 (this is a ratio and therefore has no units) A = Area of the leaves on the tree. Each leaf is 12 in2 and there are 62,500 leaves on this tree. Consider the area of the branches and trunk to be negligible. v = wind speed in m/s 12 in = .3048 m^2 x 62500 = 19050 640,000 = ((1.22(.78)(19050))/2)v^2 640,000 = 9063.99m^s(v^2) 70.61 m/s = V V=157.95 mph

Part #6 Illinois Tornadoes 14 points- 1 points for 1-9, 5 points for 10 Please download the Illinois tornado database file from Moodle. This spreadsheet contains data from the Storm Prediction Center on Illinois tornadoes from 1950 – 2017. Answer each of the questions below. Please calculate your answers in Excel (or other spreadsheet software or write a program to calculate your answers) and submit a screencapture with all your answers, similar to the example at the bottom of this page. Need help, watch this video!! https://youtu.be/mbPSRYtw4zw Questions: 1. Which decade had the most tornadoes in Illinois? 2000-2009 2. Which year had the most tornadoes in Illinois? 2006 3. Which decade had the most fatalities in Illinois? 60’s 4. What is the average Illinois tornado track length (in miles)? 4.35 miles 5. What is the average Illinois tornado track width (in yards)? 97.52 yards 6. What is the average F-Scale (EF-Scale) rating for tornadoes in Illinois? .85 7. What is the total number of tornadoes that have hit Illinois since Jan 1, 1950? 2503 8. What is the longest tornado track in this Illinois tornado database? What day did it occur? 156.7 mi, 4/9/53 9. What is the widest tornado width in this Illinois tornado database? What day did it occur? 2630, 7/23/75 10. What is the probability of a tornado hitting any square mile in the state of Illinois each year? Follow the formula below to calculate this value. Show your work. Area of Illinois = 57,915 square miles You will need to calculate: Ø Average number of tornadoes per year in Illinois Ø Average length of tornadoes in Illinois (over all years, in miles) Ø Average width of Illinois tornadoes (over all years, in miles) First calculate the average area affected by tornadoes each year by multiplying the average number of tornadoes each year in Illinois by the average width and length of Illinois’ tornadoes. Formula à

© 2020 Dept. of Atmospheric Sciences, U

ATMS 120 Winter 2021

(average area in Illinois affected by tornadoes each year) /(total area of the state of Illinois)

© 2020 Dept. of Atmospheric Sciences, University of Illinois-Urbana Champaign

6...