How thunderstorms, tornadoes and hurricanes form

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Two storms (example data)

   Storm	Water at 50 m (°C)	Wind shear (m/s)	Peak winds (mph)
   1	29.5	20	45
   2	27.5	4	120

2. 1.

   A student says a storm's strength depends only on water temperature. Noah checks the table. Which reply is best?

   • Yes: storm 1 has warmer water at 50 m, so it must be the stronger storm of the two
   • No: wind shear helps a storm by lifting more warm air into it
   • No: storm 1 has warmer water but weaker winds, since strong shear disrupts it
   • Yes: storm 2 is stronger, so cooler water makes storms stronger

3. Card

   Earth's spin gives a turning rate of about 0.0001 per second at midlatitudes. A tornado with 50 m/s winds at a radius of 100 m turns at 50 ÷ 100 = 0.5 per second.

4. 2.

   A student says tornadoes spin because of Earth's spin alone. Luz compares the two turning rates. Which reply is best?

   • No: a tornado turns about 500 times faster than Earth's effect, so shear and the updraft supply the spin
   • Yes: Earth's effect is small, but it adds up across a whole storm and starts the spin
   • Yes: a tornado turns 5,000 times slower than Earth's effect, so Earth sets the spin
   • No: a tornado turns about 5,000 times faster than Earth's effect, so shear and the updraft supply the spin
5. 3.

   Heat = mass × 4,186 J per kg per °C × temperature change. Water weighs 1,000 kg per m³. A passing storm cools the top 50 m of the ocean by 2 °C. How much heat does Esme say each square meter loses?

   • About 210 MJ per square meter
   • About 4,200 MJ per square meter
   • About 420 MJ per square meter
   • About 0.42 MJ per square meter
6. 4.

   The power carried by wind goes with the cube of its speed. A storm's winds double from 75 mph to 150 mph. By what factor does Jun say the power carried by the wind changes?

   • 2 times as much power
   • 6 times as much power
   • 8 times as much power
   • 4 times as much power
7. 5.

   A hurricane crosses into water below 26.5 °C with winds of 100 mph, and loses 12 mph a day (model data). After how long does Tala expect it to drop below 74 mph?

   • After about 8.3 days
   • After about 0.5 day
   • After about 2.2 days
   • After about 6.2 days
8. 6.

   Kira wants to test whether warm water or low shear matters more for a tropical cyclone forming. Which comparison best isolates water temperature?

   • The same disturbance on two days, with shear and water both changing
   • One disturbance with warm water and low shear, compared with a cold, calm sea
   • Two disturbances with equal shear and latitude, but different 50 m water
   • The two warmest disturbances, whatever their shear and latitude

9. One hurricane weakening (example data)

   Hour	Winds (mph)	Shear (m/s)	Water under the eye at 50 m (°C)
   0	110	5	28
   12	100	6	24
   24	80	6	24

10. 7.

    Two explanations for the weakening: stronger shear, or colder water. Ren reads the table. Which do the data support?

    • Both equally: each changed by about the same share between hours 0 and 12
    • Colder water: shear stayed near 5 to 6 m/s while the water under the eye fell from 28 to 24 °C
    • Neither: winds fall whenever a storm lasts longer than 12 hours
    • Stronger shear: it rose from 5 to 6 m/s just as the winds fell
11. 8.

    Radar shows heavy rain in a storm. Pia asks if its updraft rotates, which would make it a supercell. Which radar evidence would best show that?

    • Winds moving toward and away from the radar, side by side at the same height
    • A storm that lasts longer than 30 minutes
    • Very heavy rain across the whole storm
    • A tall cloud top reaching 12 km

12. Four days (example data)

    Day	Moisture	Instability	Lift	Storm
    1	yes	yes	yes	yes
    2	yes	yes	no	no
    3	yes	no	yes	no
    4	no	yes	yes	no

13. 9.

    Zee reads the table. Which summary of thunderstorm formation fits all four days?

    • Moisture alone makes storms, since three of the four days had moisture in them
    • Any two ingredients together make a storm, as on days 2, 3 and 4
    • Lift matters most, since the two days with lift both had storms
    • A storm formed only on the day with moisture, instability and lift together

14. Four stretches of one storm's track (example data)

    Stretch	Water at 50 m (°C)	Shear (m/s)	Winds (mph)
    1	29	5	60 to 100
    2	29	20	100 to 80
    3	25	5	80 to 70
    4	land	5	70 to 45

15. 10.

    Ari reads the table. Which summary of what strengthens and weakens a hurricane fits all four stretches?

    • It strengthens whenever shear is low, whatever the water below
    • It weakens only over land, since water and shear never matter
    • It strengthens whenever the water is warm, whatever the shear
    • It strengthens only with warm deep water and low shear together; lose either one, or cross land, and it weakens