Transcript File - COSEE Florida

Overview
 Atmosphere
and ocean one
interdependent system
 Solar energy creates winds
 Winds drive surface ocean currents and
waves
 Examples of interactions:
 El Niño-Southern Oscillation
 Greenhouse effect
Seasons

Earth’s axis of rotation tilted
with respect to ecliptic orbit
around sun

Tilt responsible for seasons
 Vernal (spring) equinox
(3/21)
 Autumnal (fall) equinox
○ sun overhead at equator
(9/23)
○ Equal day/night periods
○ sun overhead at equator
○ Equal day/night periods
 Summer solstice (6/21)
○ sun overhead at Tropic of
Cancer (23.5O N)
○ Longest day of the year in
Northern hemisphere
 Winter solstice (12/22)
○ sun overhead at Tropic of
Capricorn (23.5O S)
○ Shortest day of the year in
Northern hemisphere
Seasons

Seasonal changes and day/night
cause unequal solar heating of
Earth’s surface


Arctic circle (66.5O N)

latitude receives direct sunlight all day
on summer solstice

no direct sunlight during winter
solstice
Antarctic circle – reverse of above
Seasons
Fig. 6-1
http://go.owu.edu/~jbkrygie/krygier_html/geog_111/geog_111_lo/geog_111_lo05.html
Uneven solar heating

Angle of incidence of solar rays
per area
 Greater the angle, solar energy
spread over more area
 Equatorial regions more heat
 Polar regions less heat

Thickness of atmosphere –
absorbs or reflects energy
○ Think about South Florida
compared to Maine
Uneven solar heating

Albedo
 Albus = white
 % incident radiation reflected
back into space
 Affected by angle of sun –
more angle , more reflected
 Affected by type of surface
○ Snow/ice reflects more
○ Water surface absorbs more
○ Land absorbs most

Day/night and seasonal
cycles affect solar heating
http://go.owu.edu/~jbkrygie/krygier_html/geog_111/geog_111_lo/geog_111_lo05.html
Oceanic heat flow

Depending on latitude, there is
a net heat gain (closer to
equator) or net heat loss (closer
to poles)
 Due to albedo of ice and high
incidence of solar rays discussed
above
 Exchange of heat between
equatorial and polar regions via
ocean and atmospheric
circulation
Physical properties of atmosphere

http://www.ux1.eiu.edu/~cfjps/1400
Atmosphere is comprised
of gases and dust
 mostly nitrogen (N2)
– 78%
 Oxygen (O2) – 21%
 CO2, water vapor,
ozone (O3) are
variable
Physical properties of atmosphere
•
Fig. 6.4
Temperature profile of lower
atmosphere:
•
Troposphere
•
temperature cools
with increasing
altitude
•
Stratosphere - From 11 - 45
km
• Contains the ozone
layer
• Little vertical mixing
• Gets warmer with
increasing elevation
 solar radiation
• Mesosphere above
stratosphere
○
Troposphere - Up
to 11 km
 Weather layer
with lots of
mixing
 Gets cooler
with increasing
elevation
(decreasing air
pressure allows
expanding/cool
ing air)
http://tonydude.net/NaturalScience100/Topics/2Earth
Physical properties of atmosphere

Warm air, less
dense (rises)

Cool air, more
dense (sinks)

Moist air, less dense
(rises)

Dry air, more dense
(sinks)
Fig. 6.5
Winds, Wind Belts and Climate
Introductory geography

○
○
○
Equator = 0O latitude
Earth rotates from west to east
Wind direction indicated by direction
winds are blowing from
http://www.lakelandsd.com
Movements in atmosphere
Fig. 6.6
Air (wind) always moves from regions of high
pressure to low
 Cool dense air, higher surface pressure
 Warm less dense air, lower surface pressure

Air movements over non-rotating Earth
•
Convection or circulation cell
•
•
•
Air heated at equator  warm
(less dense) air rises
Surface air moves in to replace
rising air mass
Air expands & cools as it rises
• As it cools, becomes more
dense
• Warm air holds more
moisture than cooler air
• As air cools  moisture
condenses & forms
clouds/precipitation
Fig. 6.7
Air movements over a rotating Earth

Coriolis effect causes deflection in moving body
due to Earth’s rotation to east
 Most pronounced on objects that move long




distances across latitudes
Deflection to right in Northern Hemisphere
Deflection to left in Southern Hemisphere
Maximum Coriolis effect at poles
No Coriolis effect at equator
Movements in air on a rotating Earth

Rotational velocity increases approaching equator
Fig. 6.9
Global atmospheric circulation

Circulation cells as air changes
density due to:
 Changes in air temperature
 Changes in water vapor content

Circulation cells
 Hadley cells (0o to 30o N and S)
 Ferrel cells (30o to 60o N and S)
 Polar cells (60o to 90o N and S)
6 cells of windbelts
and boundaries:
 Intertropical
convergence zone
 Doldrums





Horse latitudes
Tradewinds
Westerlies
Polar front
Polar easterlies
•
1. Intertropical convergence zone (boundary)
• Air warms & rises at equator
 low surface
pressure (rising
air) poduce light
winds =
doldrums
• Long ago
sailing ships
became stuck
here because
of lack of
winds
Rising air cools  cloud
belt & precipitation
•
•
Winds split at top of troposphere 
•
Move toward both poles in spiral
fashion, cool
•
Sink at about 30O N & S latitude
•
2. Horse latitudes (boundary) –
low winds, high pressure ridge
•
Dry, cool, sinking air
•
Sailors would also get “stuck”
here and would through
horses overboard to conserve
water
•
Winds:
•
3. Tradewinds return to
Equator, deflected west
•
4. Westerlies move
toward poles, deflected
east
•
Winds converge at 50-60O N & S with polar air
•
•
•
5. Polar Front (boundary) - warm air rises (low press./clouds)
Upper air splits & cools  sinks near poles
Winds:
•
6. Polar Easterlies – air sinks near poles, moves from poles
toward equator
Global atmospheric circulation
High pressure zones
 Subtropical highs
 Polar highs
 Clear skies
 Low pressure zones
 Equatorial low
 Subpolar lows
 Overcast skies with lots of precipitation

Global wind belts and boundaries – review


Trade winds
 Northeast trades in Northern
Hemisphere
 Southeast trades in Southern
Hemisphere
Prevailing westerlies
Southern hemisphere
 Northern hemisphere



Polar easterlies
Boundaries between wind belts
 Doldrums or Intertropical Convergence
Zone (ITCZ)
 Horse latitudes
 Polar fronts
Modifications to idealized 3-cell model of
atmospheric circulation

Winds are more complex in nature due
to…
 Seasonal changes
 Distribution of continents and ocean
 Differences in heat capacity between
continents and ocean
○ Monsoon winds
Actual pressure zones and winds
Fig. 6.11
Seasonal Pressure and Precipitation Patterns
http://www.wunderground.com/US/Region/US/2xFronts.html
Ocean weather and climate patterns




Weather – conditions of atmosphere at
particular time and place
Climate – long-term average of weather
Northern hemisphere winds move
counterclockwise (cyclonic) around a
low pressure region
Southern hemisphere winds move
clockwise (anticyclonic) around a low
pressure region
Hurricane Francis
9/3/04
http://apod.nasa.gov/apod/image/0409/frances2_noaa.jpg
Cyclones and Anticyclones
Coastal winds

Caused by solar heating &
different heat capacities of
land and water

Sea breeze
 From ocean to land
 During day, land heats air 
rises  draws cooler ocean air
onto coast

Land breeze
 From land to ocean
 At night, warmer ocean water
rises, draws cooler land air over
coast
Fig. 6.13
Fronts and storms

Air masses
 Large volumes of air, meet at fronts

Storms
 Disturbances with strong winds, precipitation, often with
thunder and lightning
 typically develop at fronts
Fig. 6.14
Fronts and storms

United States mostly affected by polar air masses
in winter and tropical air masses in summer
Fig. 6.14

Warm front



contact between moving warm
air mass with cooler air mass
More extensive, lighter rains
Cold front



contact between moving cold air
mass with warmer air mass
Usually steep front, with heavier,
but briefer, rains
Clear skies follow behind
Cold Fronts and Warm Fronts
Tropical cyclones (hurricanes)

Caused by release of energy (latent heat of condensation)
 Low-pressure system breaks off equatorial low-pressure belt
 Surface winds feed moisture into storm
○ As water vapor condenses, heat released warms air
○ Rising warm air draws in more moist air  fueling cyclone
○ Large rotating masses of low pressure with calm “eye” (< 25 mph
winds)
 Strong winds, torrential rain outside eye
Fig. 6.16
Hurricane movement

At low latitudes, affected by trades  move west

Curve toward right in No. hemisphere  cooler
water, influenced by westerlies
Hurricane Wilma
10/25/2005
http://cimss.ssec.wisc.edu/tropic/archive/montage/atlantic/2005/WILMA-track.gif
Fig. 6.17
Hurricane Wind Patterns
Tropical cyclones (hurricanes)

Classified by maximum sustained wind speed
 Tropical storm – 39-73 mph winds
 Hurricane – above 74 mph winds
Hurricane Jeanne 09/26/2004
http://www.mapwatch.com/news-blog/images/hurricane-jeanne-track-map.gif
http://coastal.er.usgs.gov/hurricanes/jeanne/images/jeanne_radarLG.jpg
Table 6.5
Hurricane destruction
Fast winds
 Flooding from torrential rains
 Storm surge most damaging

 increased water levels from low pressure at eye
 On top of tide, most damaging at high tides
 Storm waves on top of storm surge
Historical examples:
Galveston, TX, 1900
Hurricane Andrew, 1992
Hurricane Mitch, 1998
Hurricane Katrina, 2005
Ocean climate patterns
Equatorial regions
○ Warm, lots of rain
 Tropical regions
○ Warm, less rain, trade winds
○ South Florida is tropical, defined rainy and dry season
 Subtropical regions
○ Warm, lots of wind and evaporation, find dessert areas
 Temperate regions
○ Strong westerlies
 Subpolar regions
○ Cool, winter sea ice, lots of snow
 Polar regions
○ Cold, ice

Polar oceans and sea ice

Sea ice or masses of frozen seawater form in high
latitude oceans
 Begins as small needle-like ice crystals
○ Pushes out dissolved salts  dense brine
○ Ice is much lower salinity

Rate of formation depends on temperature
Polar oceans and icebergs

Icebergs – fragments of
glaciers or shelf ice
Fig. 6-23
http://static.howstuffworks.com/gif/iceberg-calving.jpg
Climate Change
Global warming (Climate Change)


Average global temperature increased
Part of warming due to anthropogenic greenhouse (heattrapping) gases such as CO2
http://healthandenergy.com/images/carbon%20dioxi
de%201700-2000.jpg
http://earthobservatory.nasa.gov/Library/GlobalWarmi
ng/Images/temperature_vs_co2_rt.gif
Greenhouse effect




Solar radiation enter
atmosphere
Some of that radiation is
reflected to space
Some of it is reflected back
towards Earth by trace
gases and particles in the
atmosphere
Elevated levels of carbon
dioxide, methane, etc can
increase that effect
 Literally “trapping” more
heat in the atmosphere close
to the Earth
Fig. 6.24
Atmospheric Energy Balance
Greenhouse gases
Absorb longer wave radiation from Earth
 Many “greenhouse gases”

 Water vapor – most common and important
 Carbon dioxide (CO2)
 Other trace gases: methane, nitrous oxide, ozone, and
chlorofluorocarbons

Current controversy is not whether global
temperatures are increasing, but in the extent of
human impact
 The climate is changing, we cannot deny that
 The last time this happen human
population was not as large, even small
changes in climate can effect agricultural
crops, larger storms hitting populated
areas, etc.
 Is it significantly above natural background
change?
 Can we afford to keep our heads in the sand?
Consequences of global warming are not
certain, but can be predicted…
When scientists say “uncertain” it DOES NOT mean that they do not know what
they are talking about
 It does not mean that there will not be consequences
 It is just difficult to predict the extent of those consequences, the timing of those
consequences, etc.
○ This is the first time we are experiencing these changes with today’s society
○ The Earth and it’s systems are dynamic – constantly changing
- But when we talk about these changes, we are talking about thousands,
millions of years
- Our society, population boom, building of extensive cites along
coastlines, etc has been very recent
- So, let’s say for a moment that man isn’t making it worse by putting
more carbon dioxide into the atmosphere – changes are still
happening……and we have to be prepared to deal with them….


Rising sea level


Melting glaciers and ice sheets
Thermal expansion of ocean water
1-meter sea
level rise
http://resumbrae.com/archive/warming/americaMap.jpg&imgrefurl
3-meter sea
level rise

Consequences of Climate Change
 Sea level rise
 Contamination of freshwater sources
 Vulnerability of more low-lying areas to storm surges
 Shift in species distribution
 Shifts in climate patterns will affect all living organisms
 Melting ice caps & expanding deserts  threaten wildlife
 Extreme weather patterns
 Heat waves, extreme winters, larger storms in populated areas
 Droughts will affect productivity and crops
 Changing ocean chemistry
 Ocean water will become more acidic, warmer
 Changes in ocean circulation
 Spread of tropical diseases
http://iceglaces.ec.gc.ca/content_contenu/images/bearours3.jpg
http://www.ldeo.columbia.edu/edu/dees/ees/
arctic/images/05.jpg
Possible Impacts of Climate Change on South Florida

Possible sea level rise of 15-20 inches by 2060
○ South Florida Water Management plays a delicate
balancing game to ensure that areas in South Florida
don’t flood during rain events (canal system), higher
sea level would make that more difficult – areas would
be more vulnerable to flooding
○ Greater vulnerability to storm surges and erosion
○ Salt water intrusion – fresh water supply for the
population could be threatened
Reducing greenhouse gases
Greater fuel efficiency
 Alternative fuels
 Re-forestation
 Eliminate chlorofluorocarbons
 Reduce CO2 emissions

 Intergovernmental Panel on Climate Change 1988
 Kyoto Protocol 1997
Ocean’s role in reducing CO2

Oceans absorbs CO2 from
atmosphere
 CO2 incorporated in
organisms and carbonate
shells (tests)
 Stored as biogenous
calcareous sediments and
fossil fuels
 Ocean is repository or sink for
CO2
 Increases ocean acidity
enough to affect organisms
(corals)
http://www.whoi.edu/science/MCG/cafethorium/website/images/tzex_img1.jpg
Ocean’s role in reducing CO2

Add iron to tropical oceans to
“fertilize” oceans
 May increase biologic productivity that
will increase uptake of CO2 in oceanic
life
 Plankton will die and fall to bottom,
sequestering CO2 in sediment
 May not affect global CO2 levels
significantly, may not work
 May cause unknown problems in ocean
ecology for future
http://www.whoi.edu/science/MCG/cafethorium/website/images/ocean_iron.jpg
Ocean Literacy Principles








1c - Throughout the ocean there is one interconnected circulation system powered by wind, tides, the
force of the Earth’s rotation (Coriolis effect), the Sun, and water density differences. The shape of
ocean basins and adjacent land masses influence the path of circulation.
1d - Sea level is the average height of the ocean relative to the land, taking into account the
differences caused by tides. Sea level changes as plate tectonics cause the volume of ocean basins
and the height of the land to change. It changes as ice caps on land melt or grow. It also changes as
sea water expands and contracts when ocean water warms and cools.
3a - The ocean controls weather and climate by dominating the Earth’s energy, water and carbon
systems.
3b - The ocean absorbs much of the solar radiation reaching Earth. The ocean loses heat by
evaporation. This heat loss drives atmospheric circulation when, after it is released into the
atmosphere as water vapor, it condenses and forms rain. Condensation of water evaporated from
warm seas provides the energy for hurricanes and cyclones.
3c - The El Niño Southern Oscillation causes important changes in global weather patterns because it
changes the way heat is released to the atmosphere in the Pacific.
3d - Most rain that falls on land originally evaporated from the tropical ocean.
3f - The ocean has had, and will continue to have, a significant influence on climate change by
absorbing, storing, and moving heat, carbon and water.
3g - Changes in the ocean’s circulation have produced large, abrupt changes in climate during the last
50,000 years.
Sunshine State Standards









SC.6.E.7.1
Differentiate among radiation, conduction, and convection, the three
mechanisms by which heat is transferred through Earth's system.
SC.6.E.7.2
Investigate and apply how the cycling of water between the
atmosphere and hydrosphere has an effect on weather patterns and climate.
SC.6.E.7.3
Describe how global patterns such as the jet stream and ocean
currents influence local weather in measurable terms such as temperature, air
pressure, wind direction and speed, and humidity and precipitation.
SC.6.E.7.5
Explain how energy provided by the sun influences global patterns of
atmospheric movement and the temperature differences between air, water, and land.
SC.6.E.7.6
Differentiate between weather and climate.
SC.912.E.7.4
Summarize the conditions that contribute to the climate of a
geographic area, including the relationships to lakes and oceans.
SC.912.E.7.7
Identify, analyze, and relate the internal (Earth system) and external
(astronomical) conditions that contribute to global climate change.
SC.912.E.7.9
Cite evidence that the ocean has had a significant influence on
climate change by absorbing, storing, and moving heat, carbon, and water.
SC.912.P.10.4
Describe heat as the energy transferred by convection, conduction,
and radiation, and explain the connection of heat to change in temperature or states of
matter.