Chapter 8 + hurricane basics (atmosphere) Flashcards
tropical cyclone
large thunderstorm complexes rotating around an area of low pressure that have formed over warm tropical or subtropical ocean water
hurricanes
tropical cyclones in ATLANTIC AND NORTHEASTERN PACIFIC OCEAN
min winds for hurricane
74 mph
min ocean temp for hurricane
80 degrees F
hurricanes start out as a
tropical disturbance
elongated area of low pressure is a
trough
when a low pressure cell forms, the hurricane is now a
tropical depression
low pressure cell
circular areas of lower than normal atmospheric pressure that are associated with cloudy and rainy weather
min winds for a tropical storm
63 kmh
direction hurricanes circle in N hemi
counterclockwise around the low pressure cell
how many states have coastal erosion
30
3 tracks of hurricanes
- towards florida but turns back before it can hit
- passes cuba and hits gulf coast
- skirts east coast
most tsunamis come from what ocean?
pacific (85 percent)
most serious tsunami threat
hawaii
what is used to measure erosion
LIDAR
where is the most erosion
cape cod, english norfolk coast, and then california
rate of erosion depends on
resistance of earth materials
energy of waves
hurricanes cause damage in 3 ways. what are they
- storm surge
- wind damage
- freshwater flooding
what causes the most fatalities in a hurricane
storm surge (90%)
storm surge
local rise of sea level that results from hurricane winds pushing water towards the coast
where do higher storm surges develop
on broad, shallow coastlines where wind-driven water slows down from friction with the ocean bottom
also when the tide is high
WHERE ARE STORM SURGE AND WIND DAMAGE GREATEST IN HURRICANES
RIGHT FORWARD QUADRANT
overwash
deposits formed by sand eroded from the beach and coastal sand dunes that is carried landward by the stomr
washover channels
channels that the storm surge cuts through the beach and dunes perpendicular to the shoreline
particularly a problem on islands and peninsulas
most washover channels are repaired naturally by
littoral drift and wave action in the months following the storm
greatest velocity and precipitation of winds at the
eye wall
eye wall
consists of the clouds and rain that surround the calm eye of the hurricane
tsunami arrival can be predicted within
1.5 minutes
ingredients for a hurricane
- pre existing weather disturbance
- warm tropical oceans
- moisture
- relatively light winds (low wind shear)
average number of storms that develop per year
10 (6 become hurricanes)
tropical depression
an organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 mph or less
tropical storm
an organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds of 39-73mph
hurricane
an intense tropical weather system of strong thunderstorms with a well defined surface circulation and maximum sustained winds of 74 mph or greater
eye forms due to
rapidly sinking air at the center dries and warms the area
things that can end a hurricane
- wind shear
- cooler water or drier areas
- landfall (Friction)
a weakening hurricane can reintensify if it
moves into a more favorable region or interacts with mid latitude frontal systems
how wide are typical hurricanes
300 miles wide
hurricanes average forward speed
15-20 mph
why is the right side of a hurricane most dangerous
- the additive effect of the hurricane wind speed
2. speed of the larger atmospheric flow
low pressure center is formed during
tropical depression
