Hurricanes
Chapter 17
Sections 2 & 3
Pages 567-582
Hurricanes
• A tropical storm that has winds of 119km/h
or higher.
• Typically 600km in diameter.
• Hurricane season- June 1 – Nov 30.
– Western Pacific- typhoon.
– Indian Ocean- cyclone.
How Hurricanes Form
• Begins over warm water as a low-pressure
area, or tropical disturbance.
• If it grows in size and strength it becomes
a tropical storm, which may become a
hurricane.
How Hurricanes Form
• A hurricane gets energy from warm, humid
air at the ocean surface.
• As the air rises, and forms clouds, more
air is drawn in.
• Winds spiral inward towards the area of
low pressure.
How Hurricanes Form
• Inside the storm:
– Bands of heavy rain
– high winds up to 320km/h
– The lowest air pressure
– Warmest temperature.
• The lower the pressure
– The stronger the winds blowing towards the
center.
The Eye of the Hurricane
• A ring of clouds surrounding a quiet “eye”.
• Winds get stronger as the eye
approaches.
• Weather in the Eye
– Calm
– Clear sky.
How Hurricanes Move
• Hurricanes in the Atlantic Ocean are
steered by Easterly trade winds.
• Once it passes over land, the warm, moist
air from the ocean is cut off.
– The hurricane slows down
– Loses strength.
– Leaving heavy rainfall behind.
Hurricane Damage
• Hurricanes uproot trees, smash buildings,
and destroy power lines.
• Heavy rains flood roads.
Hurricane Damage
• Storm surge- most dangerous features of
a hurricane.
– A “dome” of water that comes on shore with
the hurricane that is formed by the high winds
and the low pressure.
– Up to 6m above sea-level
– Water comes ashore with the hurricane
– Washes away beaches, and destroys
buildings.
Hurricane Safety
• Advances in communications and
satellites have made tracking hurricanes
easier and have made them less deadly.
Hurricane Safety
• A hurricane watch- conditions are possible
with in the next 36 hours.
– Evacuate- move away temporarily.
• A hurricane warning- conditions are
expected within 24 hours.
– Leave immediately.
– If in a house, move to the interior away from
windows.
Storm
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