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.

   Luz reads Cards A and C. Where is a hurricane most likely to start?

   • Over 29°C water about 2° north of the equator, where the water is clearly warm enough for a storm
   • Over 27°C water right on the equator, since the pale band marks where storms like to start
   • Over 22°C water about 15° north of the equator, where Earth's turning is strong enough to spin a storm
   • Over 27°C water about 12° north of the equator, where the water is warm and Earth's turning is strong enough
3. 2.

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

   • Warm water is not enough; the turning that sets a storm spinning is too weak that close to the equator
   • 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
4. 3.

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

   • September 10, the midpoint of the busiest weeks, since storms before the busiest weeks are weaker
   • June 1, the first day of the season, since the busiest weeks are the middle of the season
   • November 30, since the season counts as started once it has ended
   • August 31, the start of the busiest weeks, since storms cannot form before then
5. 4.

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

   • 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
   • 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
6. 5.

   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?

   • Right: low winds mean a weak storm, and a weak storm brings little rain
   • Wrong: Category 1 starts at 74 mph, which is fast enough to guarantee heavy flooding in any town
   • 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
7. 6.

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

   • It is exactly Category 1, the first category above 74 mph
   • 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 Category 5, since 150 mph is far above the 74 mph start of a hurricane and close to the top of the scale
8. 7.

   Card C says to learn local evacuation routes. When is the best time to learn them, Ari asks?

   • Before the season starts, when there is time to plan; a warning is the time to act
   • After the storm's category is announced, since the route depends on how fast the winds are
   • When the warning is issued, so the route is fresh in mind
   • At the peak, around September 10, when storms are most likely
9. 8.

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

   • The days between a storm's start and the day it reaches land
   • 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 late August and September weeks, when storms can form, with no storms expected outside those weeks
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
    • Storms begin at the US coast and move back out toward the warm water of the Atlantic
    • Later storms will follow the same curve and reach the US coast in the coming seasons
    • Earth's turning near the equator bends the arrows west and then north toward the coast, which is why they curve
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: a storm needs 74 mph winds to form, and no wind speed is given for this one
    • No: the busiest weeks ended in September, so October storms cannot form
    • Yes: the water is above 27°C, 6° is beyond the 5° limit, and October falls inside the season
    • No: 6° is too close to the equator for the turning to set a storm spinning in October