Hurricane LabUnit 4

1. What is the purpose of a Hurricane?To redistribute heat in the atmosphere

2. What are the conditions needed for tropical cyclones to form?Only form over really warm ocean water of

26˚C or more (hence why hurricanes cannot form in the Maritimes)

The air must cool off really quickly the higher it goes.

The wind must be blowing in the same direction and at the same speed as the ocean surface right up to 9000 m above sea level.

Must be 500km from the equator

3. Which way do hurricanes rotate in:Northern Hemisphere:

CounterclockwiseSouthern Hemisphere:

Clockwise

4. What is the Coriolis Effect?Deflects moving objects to one side because

of the Earth’s rotation. The object is still going straight but the earth

moves underneath it, making it look like it is moving to one side.

5. When is hurricane season in the N. Atlantic Basin?June & November every year – most of them

occur between August and October though

6.

7. Stages of DevelopmentTropical Wave – ThunderstormsTropical Disturbance – Moving area of

thunderstorms that continues for 24 hoursTropical Depression – The thunderstorm is

starting to rotate, winds accelerateTropical Storm – Winds have reached 63

km/h or more

8. & 9.How are hurricanes measured?Scientists have come up with a way to categorize

hurricanes to better prepare the public. Ranking system is called the Saffir-Simpson scale:

Hurricanes are ranked 1-5 1: Weak – Damage to trees & road signs 2: Moderate – Trees, signs, roofs, piers, etc. 3: Strong – All signs, and mobile homes

destroyed, serious flooding near the coast. 4: Very Strong – Extensive damage to roofs,

windows & doors, residents living within 500 m from the shore might need to be evacuated.

5: Devastating – Severe damage to all buildings, massive evacuation of all residents living within 16 km of the shore.

10. Why do they give names to hurricanes?Makes it easier for scientists and the general

public to communicate. Quicker to use a name than a code or number for

each storm. A list of names are prepared for the upcoming

season.Alternate between boy and girl’s names and go in

alphabetical order (Q, U, X, Y, Z are not used – too difficult to find enough different names)

11. When do they retire a name?When it is a memorable hurricane that

caused significant damage.Ensure there is no confusion when people

talk about that particular storm. Ex. Hurricane Katrina

12. How do hurricanes die?When it reaches land because it no longer

has its energy source (warm water)If a hurricane travels over the colder waters

of the north it also weakens but not as quickly.

13. Impacts of a HurricaneHazards Impacts

Winds - Can destroy houses, buildings, and other structures

- Also, causes flying debris

Rain - Causes heavy flooding, especially inland areas where rivers overflow

Storm Surge - Storm surge is the fast rise in sea level

- Sea level rises because of the strong winds that are pushing the water towards the coast.

- Most damage along beaches and offshore islands

Ocean Waves - Greatest threat for those at sea