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Air-Sea Interaction (Chapter 8)
The Solar Connection
The Coriolis Effect
The Winds
Hurricane Wilma
Observation Device: GOES-12 1 km visible
imagery.
Visualization Date: October 24, 2005 15:02:23
http://www.nnvl.noaa.gov/cgibin/index.cgi?page=items&ser=109929
Atmospheric Layers
The ______________________
(air we breathe) is approximately:
78% _______________
21% _______________
<1% _______________
<0.1% ______________________
0.01% ______________________
Reasons for seasons…
In addition to Earth’s orbit
around the sun, there are
________ main reasons for
_________ ________________
of Earth:
1 - The _____________
___________ of Earth
2 - The ____________
________________ of rotation
3 - Seasonal changes in
______________ from the sun
to Earth
As the Earth revolves around the sun, the
north pole will tilt toward the sun for part of
the year (summer), and away from the sun for
part of the year (winter).
When the _____________ hemisphere has
summer, the ______________ hemisphere
has winter
As the Earth revolves around the sun, the
_____________ at which we receive sunlight
changes. In ___________, we receive
__________ angle sunlight.
Higher angle sunlight means _________
concentrated ________ and __________
summer weather.
Notice how the
lower angle sunligh
spreads out, heating
a larger area
and therefore giving
less concentrated
heat.
…so solar heating is uneven
Uneven warming causes
_________________
Convection occurs when
warm air becomes ____
_______ and ______,
then ______, dense air
comes in to _______ the
rising warm air =
_____________________
Idealized Convection on Earth
Warm air ______ at
_________, ________
air flows from _______
to replace warm air at
surface level. High,
warmer air flows
toward poles, then
cools and sinks =
circular pattern...
Idealized Convection on Earth
… but idealized
convection is an
oversimplification,
why?
Coriolis(1835) Effect…
• The path of a moving object deflects
to the ________ in the
_______________ hemisphere and
to the __________in the
_____________ hemisphere.
• … due the Earth’s rotation, wind
flows east and west as well as north
and south.
http://www-history.mcs.standrews.ac.uk/history/PictDispl
ay/Coriolis.html
Relative motion
The linear velocity of points on
Earth’s surface decreases with
increasing latitude.
At the equator (0), the eastward
speed is about 1,620 km/hr, but at
the north pole (90N) the eastward
speed is zero.
This is key to understanding the Coriolis Effect on winds and ocean currents.
Earth’s rotation and shape causes the Coriolis effect
Real Life Example:
This movie of a ball rolling across the surface of a rotating merry-go-round is a helpful
demonstration of the Coriolis force.
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/crls.rxml
•http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm
?chapter_no=visualization
Winds and the Coriolis effect
_________________ plus
________________ effect gives us
prevailing wind patterns.
Air moves horizontally from areas of
_______________ pressure to areas of
________ pressure = wind. Coriolis steers
wind to the _________ in the ___________
hemisphere.
General Circulation
http://ww2010.atmos.uiuc.edu/(Gh)/wwhlpr/global_winds.rxml
Polar Easterlies: From 60-90 degrees
latitude.
Prevailing Westerlies: From 30-60
degrees latitude (aka Westerlies).
Tropical Easterlies: From 0-30 degrees
latitude (aka Trade Winds).
The easterly trade winds of both
hemispheres converge at an area near
the equator called the "Intertropical
Convergence Zone (ITCZ)", producing a
narrow band of clouds and
thunderstorms that encircle portions of
the globe.
How do hurricanes form?
http://oceanexplorer.noaa.gov/edu/learning/player/lesson13.html
Forcasting intensity…
Tropical Cyclone Formation
Tropical cyclones form in one air mass
N
Equator
Core of tropical
cyclone rotating
counterclockwise
Stepped Art
Fig. 8-25, p. 220
Conditions Required for Tropical
Depression Formation
• Weather disturbance with __________
_________that draws in air from all directions
(usually 5° - 20° latitude)
• _______________ __________ _________ (0200m), ca. 80°F (27°C) or warmer
Hurricane Development
• ____________________: organized system of
clouds and thunderstorms; wind speed LE
_____ mph
• _______________: cyclonic circulation
develops; wind speed _________ mph; storm is
named
• _________________ (aka ___________ in the
North Atlantic): intense cyclonic winds
surrounding a well defined eye; wind speed GE
_____ mph
Saffir-Simpson Scale (NHC)
•
•
•
•
•
Category 1: 74-95 mph; minimal damage
Category 2: 96-110 mph; moderate damage
Category 3: 111-130 mph; extensive damage
Category 4: 131-155 mph; extreme damage
Category 5: GE 156 mph; catastrophic
Common tropical cyclone tracks. The breeding grounds of tropical
cyclones are shown as orange-shaded areas. The storms follow
curving paths: first they move westward with the trade winds and
usually away from the equator. Then they either die over land or
lose power over the cooler ocean of mid-latitudes.
Wilma
Hurricane Andrew
Hurricane Andrew
1992
Hurricane Mitch
http://news.bbc.co.uk/2/hi/americas/202395.stm
http://www.fortogden.com/fant-8.jpg
Are hurricanes getting more
intense due to warming seasurface temperatures?
…probably
Hurricane Impacts on Marine Life
• Sea Conditions during Hurricane Isabel
Storm Surge
• Increased ________ __________ causes
damage to marine and coastal ecosystems
Coral Reef Storm damage and
Resilience
Slows growth and
impacts framework,
but allows for
fragmentation and
regeneration
Cool water upwelling and mixing
• Hurricane Isabel trail is evident from the wake
of cool water
Temp and Salinity Profile Changes during
Hurricane Francis
Fish Kills
• ________________________________
Coastal Erosion
Sea turtle nest
exposed
Hurricane Sandy
2013
Framework is
impacted by
storm damage
but new growth
occurs within
light gaps
What about Monsoons?
From the Arabic mausim meaning season…
Summer Southwest monsoon
(Honjo and Weller, 1997)
Winter Northeast monsoon
Seasonal cycles are critical to
biological cycles too…
• Biological communities
have adapted to seasonal
cycles:
• Gray whales __________
to Arctic waters in
__________ to feed on
______ and other
________________
• Subsistence hunters in
Alaska depend on annual
migrations of marine
mammals