Earthquakes, hurricanes, floods and droughts: where and why

Grade 9 Social Studies Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Card A, sea temperature (a map, in words)

   Water of 27°C (81°F) or warmer is shaded orange over the tropical Atlantic and the Gulf of Mexico. A pale band marks the area within 5° of the equator; its water is warm, too. Card B, storm tracks: arrows show the paths of past storms. They start over the warm water, curve west and then north toward the Caribbean and the US coast. Almost no arrows start within 5° of the equator. Card C, notes: A tropical storm needs sea water of about 27°C or warmer, and it needs Earth's turning to set it spinning; that turning is too weak within about 5° of the equator. The Atlantic hurricane season runs from June 1 to November 30; its busiest weeks are late August and September (the midpoint is September 10). The Saffir–Simpson scale sorts hurricanes by wind speed alone: Category 1 starts at 74 mph and Category 5 starts at 157 mph. It does not measure rain or flooding. Public weather guidance: before the season, learn your local evacuation routes and keep water, food and a battery radio ready; when an official warning is issued, follow it.

2. 1.

   Card B shows almost no arrows starting within 5° of the equator, yet the water there is warm. Milo asks why.

   • Earth's turning is too strong near the equator, so storms are torn apart before they can start
   • The map shows past storms, so the gap probably means few storms were recorded near the equator in those years
   • Warm water is enough to start a storm, so the pale band must hold cooler water than the orange area
   • Warm water is not enough; the turning that sets a storm spinning is too weak that close to the equator
3. 2.

   Noah's family wants supplies ready before storms become likely. Which date is the best deadline?

   • August 31, the start of the busiest weeks, since storms cannot form before then
   • September 10, the midpoint of the busiest weeks, since storms before the busiest weeks are weaker
   • November 30, since the season counts as started once it has ended
   • June 1, the first day of the season, since the busiest weeks are the middle of the season
4. 3.

   On Card A, a spot is shaded orange and lies inside the pale band. What is the best reading, Pia asks?

   • Water that is not warm enough, since the pale band marks cooler water near the equator
   • A place no storm can cross, since almost no arrows start inside the pale band
   • A likely start, since orange means the water is warm and warm water is enough to start a storm there
   • The water is warm enough, but the spot is too near the equator for a storm to start spinning
5. 4.

   A Category 1 storm is dropping heavy rain on a town. Ren says the low category means flooding will be small. What is the best reply?

   • Wrong: Category 1 starts at 74 mph, which is fast enough to guarantee heavy flooding in any town
   • Right: low winds mean a weak storm, and a weak storm brings little rain
   • The category rates wind speed, so it says little about how much rain or flooding to expect
   • Right, because the scale rates rain first and wind second
6. 5.

   A storm's winds reach 150 mph. Tala checks the scale on Card C. What can be said?

   • It is a hurricane, since it is above 74 mph, and it is below Category 5, since it is under 157 mph
   • It is not a hurricane, since 150 mph is under the 157 mph start
   • It is exactly Category 1, the first category above 74 mph
   • It is Category 5, since 150 mph is far above the 74 mph start of a hurricane and close to the top of the scale
7. 6.

   Zee's notes use the words 'storm track'. What does a storm track show on Card B?

   • The path a past storm followed, drawn as an arrow from where it started
   • The path a coming storm will follow, drawn before the storm starts
   • The area of warm water where storms can start, drawn as orange shading on Card A
   • The strength of a storm, shown by how long its arrow is
8. 7.

   A map caption says 'hurricane season'. What does Card C say that term means, Bo wonders?

   • The late August and September weeks, when storms can form, with no storms expected outside those weeks
   • June 1 to November 30, when Atlantic hurricanes are expected, busiest in late August and September
   • The months when the sea is 27°C or warmer, which end on November 30
   • The days between a storm's start and the day it reaches land
9. 8.

   Why do forecasters look at the sea-temperature map and the storm-track map together, Esme asks?

   • They show the same thing, so either map alone would be enough
   • Tracks show where the water is warm, and the sea map shows where storms went afterward
   • Warm water shows where storms can start; tracks show where past storms went afterward
   • Together they give the exact category of each storm that is coming
10. 9.

    Card B's arrows curve west and then north. What is the best reading, Jun asks?

    • Past storms that began over warm water moved west, then north toward the Caribbean and US coast
    • Earth's turning near the equator bends the arrows west and then north toward the coast, which is why they curve
    • Later storms will follow the same curve and reach the US coast in the coming seasons
    • Storms begin at the US coast and move back out toward the warm water of the Atlantic
11. 10.

    A tropical storm forms 6° north of the equator over 29°C water in October. Does Card C allow it, Kira asks?

    • No: the busiest weeks ended in September, so October storms cannot form
    • No: a storm needs 74 mph winds to form, and no wind speed is given for this one
    • No: 6° is too close to the equator for the turning to set a storm spinning in October
    • Yes: the water is above 27°C, 6° is beyond the 5° limit, and October falls inside the season