Lecture 18: Hurricanes Flashcards
1
Q
what are hurricanes
A
- tropical cyclones
- exporting heat from tropics to mid latitudes
- ocean heat is the primary energy source, hurricanes gain energy as they travel over the ocean
- rain is the hurricanes release of energy
2
Q
pressure gradient
A
- eye of hurrivane is a low pressure region
3
Q
coriolis effect
A
in the northern hemisphere
- the impact of earth’s rotation on winds
- in the NA winds are deflected to the right when flowing towards the eye
4
Q
centrifugal force
A
- pull to the right
5
Q
friction
A
slows down the wind
6
Q
birth ingredients
A
- water temperature > 27 C
- warm humid unstable air
- in northern hemisphere surface winds rotating counterclockwise
- significant Coriolis effect to sustain rotating surface winds
- weak high-altitude winds
7
Q
tropical disturbance
A
- poorly organized cluster of thunderstorms
- weak surface winds
- diameter 200-600 km
frequent in tropical regions
8
Q
tropical depression
A
- clearly defined low pressure central area
- organized wind circulation initiated
- vertically: strong winds lift warm and moist air upwards in the central area
9
Q
tropical storm
A
- classical hurricane structure but no eye
- counterclockwise winds (64-118 km/h)
- storms are names
10
Q
hurricane
A
- classical hurricane structre with a well-developed eye
- eye forms wehn wids > 118
11
Q
decline
A
- hurricanes decline rapidly after they make landfall
12
Q
rainbands
A
- dense clusters of thunderstorms spiraling slowly counterclockwise
- hurriane diamter ~500 km
- most intense rainfall
13
Q
eye
A
- similar to a chimney
- area of lowest pressure
- surface wind converge
- winds spiral up along eye wall
- high altitude winds diverge
14
Q
vertical movements of air
A
- air must overcome gravity
- rising air loses energy and becomes cooler
- sinking air gains energy and becomes warmer
- cool air sinks inside the eye
- warm air
15
Q
storm surges
A
through succion, low pressure below eye creates a mound of water
- winds deform and push mount towards land
- in northern hemisphere: surge and strongest winds on the right side of the advancing storm
16
Q
cape verbe type hurricanes
A
- thunderstorms forming in the sahel
- intensity increases above atlantic
- approaching north america, path curves to the right
17
Q
ITCZ (intertropical convergence zone)
A
- sone near equator where northern and southern hemisphere trade winds converge
- exact location varies throughout the year
- storms frequent when ICTZ above caribbean sea
18
Q
post tropical transition
A
- in north atlantic hurricanes venturing north of 30-40 degrees latitude might experience post tropical transition
- move into cooler and faster air streams
- accelerate
- deform
- hurricanes experiencing post-tropical transition might merge with an existing depression and regain strength
