How thunderstorms, tornadoes and hurricanes form
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
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 A student says a storm's strength depends only on water temperature. Noah checks the table. Which reply is best?
- Yes: storm 2 is stronger, so cooler water makes storms stronger
- 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 1 has warmer water at 50 m, so it must be the stronger storm of the two
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.
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
- No: a tornado turns about 5,000 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
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?
- 6 times as much power
- 4 times as much power
- 2 times as much power
- 8 times as much power
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 6.2 days
- After about 8.3 days
- After about 0.5 day
- After about 2.2 days
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
- Two disturbances with equal shear and latitude, but different 50 m water
- The two warmest disturbances, whatever their shear and latitude
- One disturbance with warm water and low shear, compared with a cold, calm sea
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 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
- 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
- Colder water: shear stayed near 5 to 6 m/s while the water under the eye fell from 28 to 24 °C
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
- Very heavy rain across the whole storm
- A tall cloud top reaching 12 km
- A storm that lasts longer than 30 minutes
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 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
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 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 strengthens whenever the water is warm, whatever the shear
- It weakens only over land, since water and shear never matter
- It strengthens only with warm deep water and low shear together; lose either one, or cross land, and it weakens
Saffir-Simpson Hurricane Wind Scale (NHC)
Category Sustained winds (mph) 1 74 to 95 2 96 to 110 3 111 to 129 4 130 to 156 5 157 or higher Milo reads the scale. Which summary of what the scale rates fits the table?
- It rates peak wind alone, in uneven bands: 15 mph for Category 2, 27 for Category 4
- It rates peak sustained wind alone, in equal bands that are 20 mph wide
- It rates wind, rain and storm size together, in bands that are each exactly 20 mph wide
- It rates the total size of the storm, using bands that grow by 15 mph