Hurricane Lab Unit 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: • Counterclockwise • Southern 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
7. Stages of Development • Tropical Wave – Thunderstorms • Tropical Disturbance – Moving area of thunderstorms that continues for 24 hours • Tropical Depression – The thunderstorm is starting to rotate, winds accelerate • Tropical 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.