Hurricanes Flashcards
Historically, what is the most destructive aspect of a hurricane striking a low-lying coastal area?
Storm surge
What is the difference between a hurricane and an extratropical cyclone?
Hurricanes:
- have no fronts
- develop within a uniform warm and humid air mass
- is a warm-core system
Sustained surface winds in a hurricane are
119km/h or higher
Typical weather within the eye of a hurricane consists of
Light winds and clear skies
Why do hurricanes typically not form in latitudes over 30 degrees north?
Because the surface ocean water is too cold
Why don’t hurricanes form at the equator?
There is no Coriolis effect
What source of energy sustains hurricane circulation?
Latent heat
When do most northern hurricanes occur?
From June through November
At latitude 10 degrees N, Atlantic basin hurricanes generally…
Drift slowly to the west
At latitude 10 degrees N, tropical cyclones are steered by the…
Northeast trade winds
The central pressure is … in a hurricane than in a typical extratropical cyclone
Lower
The eye of a hurricane typically …
- shrinks in diameter as the storm intensifies
- features subsiding air
- is surrounded by a ring of cumulonimbus clouds
Hurricane formation requires a sea-surface temperature of at least __ degrees C through a depth of about 60 meters
26.5
What ultimately governs the rate of evaporation of seawater?
Sea-surface temperature
What forces are operating in a hurricane?
- Coriolis effect
- Friction
- Pressure gradient force
- Centripetal force
What is the minimum latitude where the Coriolis effect is strong enough to sustain hurricane circulation?
About 4 degrees
Where do hurricanes or tropical storms never occur?
The west coast of South Africa
Where are some places where hurricanes occur frequently?
- The Indian Ocean east of Madagascar
- The Arabian Sea
- The Bay of Bengal
- The Gulf of Mexico
Why don’t hurricanes usually form off the coast of South America?
Because of the shear produced by strong winds in the middle and upper troposphere
What consequence of hurricanes causes the most fatalities?
Coastal and inland flooding
What happens to hurricane winds once the system reaches land?
It rapidly weakens
What happens to surface winds as hurricanes track from the sea to land?
They get weaker and shift towards the eye
What happens as a hurricane tracks inland?
- Its winds diminish
- Its pressure rises
- Rain continues
- Horizontal pressure gradient weakens
What do major hurricanes rate on the Saffir-Simpson Hurricane Intensity Scale?
3 or higher
What is the first sign that a hurricane may be developing over tropical seas?
The appearance of an organized cluster of cumulonimbus clouds
What triggers a tropical disturbance?
- The Intertropical Convergence Zone (ITCZ)
- A trough in the westerlies intruding into low latitudes
- An easterly wave
What conditions could inhibit the development of tropical storms and hurricanes over the tropical eastern Atlantic?
- Subsidence of air on the eastern flank of the Bermuda-Azores high
- Strong vertical wind shear
- Low vapor pressure in the middle troposphere
- Unusually low sea-surface temperatures
What is the most prudent strategy for residence when a hurricane threatens low-lying coastal areas?
-Evacuate to an inland shelter
Where is the most hurricane-prone location in the United States?
Florida
What is the major source of energy in a hurricane?
Release of the latent heat of vaporization
Where can the highest wind speeds occur in a hurricane?
In the eye wall
When do hurricanes dissipate?
- When they move over colder ocean water
- They move over land
- Surface inflow of air exceeds upper-level outflow of air
What is often situated above a hurricane?
An anticyclonic air flow
What kind of air does a tropical storm or hurricane develop in?
Maritime tropical air
What does it mean when a hurricane is approaching you from the East and the wind changes from very strong northerly to calm?
The eye is overhead and the other half of the storm is yet to come
Where do easterly wave originate from?
North Africa
