chapt15u - wmhstiffanyscience

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Transcript chapt15u - wmhstiffanyscience

Air, Weather, and Climate
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accompanying textual information
questions to answer
and the movie/jpeg/gif or whatever the
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Questions can be answered informally, but
remember that you want to get as much
info as possible.
• The Atmosphere and Climate
– Greenhouse Effect
– Convection Currents
• Weather
– Coriolis Effect
– Cyclonic Storms
• Climate
– El Nino
– Climate Change
Earth As a System (TD 27)
• The Earth is a complex, living organism not too disimilar
to you and I.
• The Gaia theory by James Lovelock is an example of
this concept.
• The theory asserts that living organisms and their
inorganic surroundings have evolved together as a
single living system that greatly affects the chemistry and
conditions of Earth’s surface.
• Some scientists believe that this “Gaian system” selfregulates global temperature, atmospheric content,
ocean salinity, and other factors in an “automatic”
• Earth's living system appears to keep conditions on our
planet just right for life to persist!
Two Different Atmospheres
• How does early Earth’s atmosphere differ
from todays?
Global History
• What techniques and materials do
scientists use to confirm global history
dates for geochemical phenomenon?
The Past
• What four reasons have been given for
past climactic changes?
Chemical Composition of the
• 77% nitrogen, 21% oxygen, with traces of argon, carbon
dioxide (340 ppm) and water vapor
• Tiny amount of carbon dioxide important to the
maintenance of the Earth's surface temperature via the
greenhouse effect.
• The greenhouse effect raises the average surface
temperature about 35 degrees C above what it would
otherwise be (from a frigid -21 C to a comfortable +14
C); without it the oceans would freeze and life as we
know it would be impossible.
• Weather - A description of physical
conditions of the atmosphere.
• Climate - A description of the long-term
weather pattern in a particular area.
– Weather and climate are primary determinants of
biomes and ecosystem distribution.
Vertical Structure of the
Atmosphere (TD 28)
Remember to click on the different buttons AND the terms for more info!
The Atmosphere and Climate
Describe the 8 parts of the atmosphere and
the function of each part.
A boundary layer!
• The tropopause is a region
between the troposphere and
the stratosphere
• It is a transition boundary that
limits mixing between the
troposphere and the upper
• The boundary between the
troposphere and the
stratosphere varying in altitude
from approximately 8
kilometers (5 miles) at the
poles to approximately 18
kilometers (11 miles) at the
• This permits the troposphere to
remain relatively undisturbed.
Troubled Tropopause?
• Santer and colleagues say
• increased amounts of greenhouse gases warm the
• reduced levels of ozone cool the stratosphere.
• Both these effects increase the height of the tropopause.
– The results provide independent support for troposphere
warming and overturn controversial claims based on satellite
measurements that showed little or no tropospheric warming
over the last 20 years.
• The team found that its results agreed well with other
‘fingerprint’ studies. These include
– increases in Earth and sea -surface temperatures,
– sea-level pressure patterns and
– the melting of the polar ice caps.
Let’s hear it for the Atmosphere!
• The troposphere, stratosphere,
mesosphere, and thermosphere act
together as a giant safety blanket.
• keep the temperature on the earth's
surface from dipping to extreme icy cold
that would freeze everything solid, or from
soaring to blazing heat that would burn up
all life.
• In the study of air pollution control the
layers of the air that are most important
are the troposphere and the stratosphere.
Convection and Atmospheric
• Lighter air rises and is replaced by cooler,
heavier air, resulting in vertical convection
– Transport energy and redistribute heat.
• Much of solar energy absorbed by the
earth is used to evaporate water.
– Energy stored in water vapor as latent heat.
• If condensation nuclei are present, or if
temperatures are low enough, condensation will
lead to precipitation.
• Releasing latent heat causes air to rise,
cool, and lose more water vapor.
– Rising, expanding air creates an area of
relatively high pressure at the top of the
convection column.
• Air flows out of high-pressure zone towards areas
of low-pressure, where cool, dry air is subsiding.
Coriolis Effect
• As air warms at the equator, rises, and moves
northward, it sinks and rises in several
intermediate bands, forming circulation cells.
– Surface flows do not move straight North and South,
but are deflected due to Coriolis Effect.
– Go to
a/coriolis/view_interactive and play with the cannon
to see how the Coriolis effect works.
Coriolis Effect
• Major zones of subsidence occur at about
30o north and south latitude.
– Where dry, subsiding air falls on continents, it
creates broad, subtropical desert regions.
• Winds directly under regions of subsiding air are
often light and variable.
To understand the convection cells that distribute heat over the whole earth,
let's consider a simplified, smooth earth with no land/sea interactions and
a slow rotation.
Under these conditions, the equator is warmed by the sun more than the
The warm, light air at the equator rises and spreads northward and
southward, and the cool dense air at the poles sinks and spreads toward
the equator. As a result, two convection cells are formed.
• The slow rotation of the earth toward the east causes the air to be
deflected toward the right in the northern hemisphere and toward the
left in the southern hemisphere. This deflection of the wind by the
earth's rotation is known as the Coriolis effect.
Convection Currents
• Subsiding air is compressed as it
approaches the earth’s surface where it
piles up and creates an area of high
pressure at the surface.
– Air flows out of this region back towards low
pressure, closing the cycle.
Convective Cloud Systems (TD 37)
• This Quicktime movie will help you learn
more about how clouds are formed!
• Don’t forget to read the text and answer
the questions!
Water Vapor Circulation on Earth
(TD 20)
• View the simulation and keep the “cannon”
in mind as you watch.
• Don’t forget to read the information.
• Be able to answer the questions.
Wind “Belts”
• Hadley Cells, Ferrell Cells and Polar Cells
are distinctive forms of convection that
form at different latitudes.
Hadley Cells
This is the cell that is closest to the equator.
It consists of winds converging and rising at the equator
and then diverging north and south of the equator as it
reaches the upper troposphere.
The winds then sink at 30 degrees latitude as they
converge with winds in the Ferrell Cell.
They hit the surface and diverge back to the equator to
complete the cell. This provides the equator-ward wind
component of the Trade Winds.
Polar Cells
• This cell has winds rising up at 60 degrees
latitude and spreading out pole-ward as they
reach the upper troposphere.
• The winds sink down at the poles and then
diverge towards the equator until they reach 60
degrees latitude where they rise up again to
complete the cell.
• They provide the equator-ward component of
the Polar Easterlies.
• The mid-latitude jet stream is found in the upper
troposphere where the Ferrell and Polar cells
Ferrell Cells
• This cell has winds sinking at 30 degrees
latitude and then traveling pole-ward as they hit
the ground and diverge with winds from the
Hadley Cell.
• This provides the pole-ward component of the
mid-latitude westerlies.
• These winds travel towards the poles until they
converge with winds in the polar cell at 60
degrees latitude.
• These winds then rise up and spread out
equator-ward to complete the cell.
Air rises in the Inter Tropical Convergence Zone (ITCZ) to the top of
troposphere, then spreads polewards. Jet streams are found just
below the tropopause (the interface between the troposphere and
stratosphere) where the Hadley and Ferrell, or Ferrell and Polar cells
converge. The regions of surface high and low pressure are shown. In
the stratosphere, the air is much more stable and less well mixed than
the troposphere.
Jet Streams
• Jet Streams - Large-scale upper air flows.
– Generally follow undulating paths where
Hadley and Ferrell cells meet.
Three Jet Stream TD’s
• The Jet Stream has a definite effect on
weather, especially in Maryland.
• Observe and read the info for the following
TD sites
– Giving Rise to the Jet Stream (TD 8)
– Jet Stream and Horizontal Temperature
Gradients (TD 11)
– A Five Day View of the Jet Stream (TD 7)
Air Masses
• What are the five types of air masses and
their locations?
• Equitorial, tropical, polar, arctic; either
continental or maritime
• How are they classified?
• Moisture content; maritime or continental
Air Masses
Types of Fronts
Compare and Contrast Warm
and Cold Fronts (TD 2)
• See how they work at TD site named above.
• Cold Front - Boundary formed when cooler air
displaces warmer air.
– Cold air is more dense, thus hugs ground and pushes
under warm air.
• Warm air cooled adiabatically. (wha? Look it up!)
• Warm Front - Boundary formed when warm air
displaces cooler air.
– Warm air is less dense and slides over cool air,
creating a long wedge-shaped band of clouds.
Cloud Types (TD 26))
• Cloud identification is not only fun, but can help
you predict weather.
• Go to the TD site to learn more about this
fascinating information!
• Quick – what type of clouds are in the sky right
• Don’t believe it? Go to
– Click on the different types of clouds
– The click on the various cloud pictures to see what
type of weather they “predict”.
Rating the Wind
Convection currents cause wind to form.
Rating the wind speed is very important. Go
fort.html to learn about the Beaufort Scale.
• The Beaufort Scale is used to determine
wind speed and physical changes seen
during that wind speed.
Observe Images of Climate Zones
(TD 24)
• Climate and weather are intimate
bedfellows. As a result, unless you have
DRASTIC changes, climate doesn’t
necessarily change.
• Go to the TD above, observe the images,
read the accompanying info and answer
the questions.
20 Year Map of Global Rainfall
(TD 3)
• There are definite patterns that can be
seen when viewing the weather.
• Make sure to “connect” the information to
the Coriolis effect.
Ocean Temperatures and Climate
Patterns (TD 19)
• This animation from The New Media
Studio illustrates how the atmosphere and
ocean together shape wind, current, and
rainfall patterns in the tropical Pacific.
Ocean Current TD’s
• View the following TD sites and read the
• Questions/notes – you know the drill!
– Shipwrecks Reveal Ocean Currents (TD 22)
– Examine Global Surface Currents (TD 17)
– What Causes the Gulf Stream? (TD 21)
– Ocean Temperatures and Climate Patterns
(TD 19)
Ocean Currents
• Warm and cold ocean currents strongly
influence climate conditions on land.
– As surface water moves, deep water wells up
to replace it.
• Ocean circulation also driven by differences in
water density.
– Gyres
Seasonal Winds and Monsoons
• Monsoon - Seasonal reversal of wind
patterns caused by differential heating and
cooling rates of oceans and continents.
– Most prevalent in tropical countries where
large land area is cut off from continental air
masses by mountain ranges and surrounded
by a large volume of water.
The Great Flood of 1993 (TD 12)
• This TD describes how an anomalous
weather patterned formed and stayed in
one place, causing the worst flooding ever
seen in the United States.
Cyclonic Storms
• When rising air is laden with water vapor,
latent energy released by condensation
intensifies convection currents and draws
up more warm air and water vapor.
– Storm cell will exist as long as temperature
differential exists.
• Hurricanes (Atlantic)
• Typhoons (Western Pacific)
• Cyclones (Indian Ocean)
How Hurricanes Form (TD 10)
– Hurricanes form in the tropics where the water and
air are warm and moist. There are many factors which
need to be just right in order for a hurricane to form.
Scientists aren't sure why all these factors are needed
but know that they are important. A study found that
out of 608 possible storms only 50 developed into
tropical storms.
Hurricane Elana
– One ingrediant is a low pressure area which forms over a large
area of warm water.
– The air being drawn into the central low pressure is curved due
to the Coriolis Effect.
– Surface friction also causes the wind around the low to spiral
toward the center.
– This gives the hurricane a circular rotation. The incoming air
must go somewhere so it rises.
– This rising air, which is saturated with water, cools and
condenses to form clouds. The latent heat given off when the
water condenses causes the upper air to warm and increase in
– This high pressure area is the reason why weather is nice in the
eye of a hurricane.
– This is the start of a feedback mechanism which continues to
intensify the hurricane as long as there is warm water from which
to draw energy.
Tropical Storm Agnes, 1972
• Once a hurricane moves over
land, the large energy supply
from the ocean is no longer
available and the feedback no
longer intensifies the storm. As
it continues over land it begins
to lose strength and eventually
• However: the storm can
downgrade to a tropical storm
and continue to wreak havoc
with still strong winds and
large amounts of rain, which
leads to flooding.
• Hurricane Agnes was only a
Cat. 1 hurricane, yet it
produced rainfall that was
TWICE as destructive as any
storm seen in the 20th C!
Tractor trailers were
floating around like toy
trucks up and down
the Patapsco River.
At the height of the
storm, flood waters
completely engulfed
the bridge between
Ellicott City and
Baltimore County.
The Patapsco River at Ellicott City rose five feet in ten minutes,
then twenty-five feet in a half hour, finally cresting at an unheard
of forty-five feet above normal.
In Sykesville/Henryton area
The Henryton Road bridge lies on its side where Agnes left it.
Adding insult to injury
• Hurricane winds can spawn tornadoes
over land.
• Tornadoes will form in the NE sector of the
hurricane’s wind field
• Complete the lab Hurricane Tracking and
Prediction tonight at home.
• 50 pts. Due tomorrow.
• Also, go to
to learn about the Saffir-Simpson Scale for
hurricane rating
How do Tornados Form? (TD 9)
• Tornadoes - Swirling funnel clouds.
– Rotation not generated by Coriolis forces.
– Generated by “supercell” frontal systems
where strong dry cold fronts collide with warm
humid air.
• Greater air temperature differences in Spring thus
more tornadoes.
– Spinning - Rolling vortex tubes.
– Downbursts - Disorganized supercells.
SuperCells and Hook Echos
Supercell Anatomy
• Ask to see the “Forces of Nature” DVD for
• View the DVD and take notes if you need
more info on how tornadoes form
It Ain’t the Size…
• No really - it isn’t the size that determines
the power of a tornado.
• Go to the TD 14 Rate Tornado Damage
which describes the Fujita Scale
• While your at it, consider Chasing
Tornados (TD 4)
• Driving Forces and Patterns
– Periodic weather cycles detected.
• Solar magnetic cycles
• Milankovitch Cycles - Periodic shifts in earth’s orbit
and tilt.
– Change distribution and intensity of sunlight reaching the
» Ice cores show drastic changes may have occurred
over short periods of time (decades).
Milankovitch Cycles
• These very important cycles have a
definite effect on glacial advance and
• Go to
ations/ch18.htm and scroll down to the
Milankovitch Cycles. Click on the
animation and take notes as need.
• Drawing pictures might help too!
El Nino Southern Oscillation
• Large pool of warm surface water in
Pacific Ocean moves back and forth
between Indonesia and South America.
– Most years, the pool is held in western Pacific
by steady equatorial trade winds.
• Every three-five years the Indonesian low
collapses and the mass of warm surface water
surges back east.
Global Weather Machine (TD 29)
• Just how does El Nino control the global
• Check out this TD to get the inside scoop!
• Also, go to
ming/a/elninolanina.htm to read a short
essay on the possible relationship
between Global Warming, El Nino, and his
sister La Nina.
El Nino Southern Oscillation
– During an El Nino year, the northern jet
stream pulls moist air from the Pacific over the
• Intense storms and heavy rains.
– During intervening La Nina years, hot, dry weather is
often present.
– Pacific Decadal Oscillation - Very large pool of
warm water moving back and forth across the
North Pacific every 30 years.
Pacific Ocean
WEST Pacific
EAST Pacific
Earth System: El Nino (TD 5)
• Also view and answer questions on
– The Atmosphere, Carbon Dioxide, & Climate Change:
Mathematical Calculations to Describe Climate & the
Atmosphere handout (websites work)
– Earth System: El Nino’s Influence on Hurricane
Formation (TD 6)
Think about it! In 2005, a La Nina year, the U.S.
experienced multiple hurricanes, the worst being
Katrina and Rita. In 2006, the beginning of an El Nino
year, we had one – Ernesto. And, the Northwest U.S.
and Southwest Canadian coasts have been socked
by continual flooding rains or large snowstorms!
Research it!
• Pick ONE of the El Nino Southern Oscillation
(ENSO) related topics on the next page and
create a short PowerPoint Presentation on it (no
more than 10 slides, PLUS the Title Slide and Lit
Cited Slide)
• Last slide will be a Literature Cited slide, using
the CSE method of Literature Citation. Go to
• Use BOTH online and print materials from the
Media Center
• 50 points.
ENSO and…
Rift Valley Fever
Australian Encephalitis
• Economic Problems (find
an affected country and
report on how ENSO has
caused economic
• Natural Disasters such as
– Flooding in Ecuador
– Hurricanes, like Katrina
– Torrential rains causing
– Volcanoes
Energy and the Greenhouse
• Of the solar energy that reaches the outer
– About one-quarter is reflected by clouds and the
– Another quarter is absorbed by carbon dioxide
water vapor, ozone and a few other gases.
– About half reaches the earth’s surface.
Energy Balance
Do the math! How much energy does the earth actually hold on to?
Energy and the Greenhouse
• Surfaces that reflect energy have a high
albedo (Reflectivity).
– Fresh clean snow
– Dark soil
– Net average of earth
So how important is the Albedo
• Go to
nsoon/ and read this case study.
• Just exactly how important is the impact of
global warming the Himalayan snow pack?
• What is the relationship between the
Himalayan snow pack to nitrate levels in
the Arabian Sea?
• What is the result of this relationship?
Energy and the Greenhouse
• Most solar energy reaching the earth is
visible light.
– Energy reemitted by the earth is mainly
infrared radiation (heat energy).
• Longer wavelengths are absorbed in the lower
atmosphere, trapping heat close to the earth’s
The Electromagnetic Spectrum
(TD 36)
• If you have trouble remembering your
physics (or didn’t take physics), go to this
TD regarding the spectrum and
• Very IMPORTANT info!
Greenhouse Effect
• Increasing atmospheric CO2 due to
human activities appears to be causing
global warming.
• We will learn more about this later!
Rapid Warming Spreads Havoc
• Go to
72.html and answer the following questions:
• How is global warming leading to an increase in
the mountain pine beetle?
• What is the level of devastation in acreage? In
cost to Canada’s economy?
• What fears have been generated by the rapid
spread of this beetle?
• What attempts at control have been made?
Have these attempts been successful?
Global Warming: Physics of the
Greenhouse Effect (TD 33)
• Okay, so we all toss the terms around, but
do you really know what causes the
greenhouse effect? Use this TD to help
you become an “expert” on the subject!
Sources of Greenhouse Gases
• Carbon Dioxide - Fossil-fuel burning.
• Atmospheric levels increasing steadily.
• Methane – Ruminants (cows, goats,
camels; Coal-mines.
• Absorbs more infrared than CO2.
• Chlorofluorocarbons (CFC’s) –
Refrigerants and useed in Aerosol cans
• Began being phased out of use in 1987
• Nitrous Oxide - Burning organic material.
Global Warming: Carbon Dioxide
and the Greenhouse Effect (TD 23)
• There is much speculation regarding this
concept, especially on the part of the Bush
• Also view the information from Earth
System: Ice Age and Global Warming
(TD 16 )
Hurricane Katrina: Possible Causes
(TD 30)
• Could global warming be responsible for
Hurricane Katrina? Check it out!
CO2 Concentrations at Mauna Loa
Observatory, Hawaii (TD 31)
• What data exists to prove that CO2
concentrations are increasing globally?
This TD will help explain what has been
• Also view TD 32 Greenland Ice Sheet
Project 2: A Record of Climate Change to
see more evidence of rising CO2 levels.
• Paper Activity: Global Warming and
Atmospheric CO2 correlation
• Virtual Laboratory: Photosynthesis and
Carbon Dioxide Levels
Current Evidence of Climate
• World Meterological Organisation (WMO)
– Global average surface temperature rose 0.6o
C during 20th century.
– Ten hottest years have been since 1990.
– Severe weather events have increased
– Average summer and winter temperature in
Alaska are higher than average.
Current Evidence of Climate
• Retreating alpine glaciers.
– Mt. Kilimanjaro
– Glacier National Park
• Wild species forced into new ranges.
– Altered migration routes.
• Coral Reef Bleaching.
– Higher water temperatures.
Potential Global Climate
Winners and Losers
• Residents of extreme northern areas
would enjoy warmer temperatures and
longer growing-seasons.
• Plant growth patterns may be altered.
• One-third of population living in areas
likely flooded by rising seas.
• More evaporation may cause severe
– Infectious disease likely to spread faster.
– Circulation patterns may cause more snowfall
at poles - New ice age ?
Is the Day After Tomorrow a Real
• Maybe! Evidence shows that this
occurred 8200 years ago!
• Go to
dn8558 and take notes on this fascinating
• Also go to these TD sites to learn more
about the reality of this occurring!
– Great Ocean Conveyor Belt: Part I (TD 35)
– Great Ocean Conveyor Belt: Part II (TD 34)
What do the Experts Think?
• National Geographic ran an article on the
same idea.
• Go to
2004/05/0518_040518_dayafter.html to
see what they say.
• And, from our experts at US News and
World Reports
And finally, to sum up…
• From the physics department at University
of California at San Diego
• Go to
ectures/17_global.ppt#272 ,18,Last
Assignment and take notes.
• DON’T do the homework assignment at
the bottom. It’s for Dr. Murphy’s students.
Human-Caused Global Climate
• In 1988, the Intergovernmental Panel on
Climate Change (IPCC) was formed.
• If you are a policy wonk, you can check it
out at
– Released third climate report in February
• Recent changes in world’s climate have had
discernable impacts on physical and biological
– Human activities must be at least partially responsible.
International Climate
• Kyoto Protocol (1997)
– 160 nations agreed to roll back carbon
dioxide, methane, and nitrous oxide
emissions about 5% below 1990 levels by
• Sets different limits for different countries,
depending on prior output.
– Developing countries exempted.
To learn more about the Kyoto
• Go to
yoto_protocol%2Fitems%2F2830.php to get the
fundamental info on the Kyoto Protocol.
• Don’t forget to click on the “More information on
commitments and Kyoto mechanisms “ at the
bottom of the page. (if you are in PowerPoint,
clicking the above sentence will take you right to
the webpage).
Should the U.S. Ratify the Kyoto
• Read the packet on the Kyoto Protocol.
• Also, go to
ocol/i/kyotoprotocol.htm and take notes on
this topic.
• What do you think about this?
Controlling Greenhouse
• Reducing carbon dioxide levels.
– Renewable energy sources may offer a better solution
to climate problems. We’ll study these later.
• Capturing and storing carbon dioxide.
– Carbon Management
• Planting vegetation – what are the results of the CO2 and
vegetation lab?
• Emissions trading or “cap and trade” system – Go to to read more
about this system
• Read and answer the guide questions for “Can We Bury
Carbon Dioxide?”
In a Nutshell
• Go to
Earth’s Climate System for an overview of
everything you have learned (and a little
more!) in this Ppt.
• The Atmosphere and Climate
– Greenhouse Effect
– Convection Currents
• Weather
– Coriolis Effect
– Cyclonic Storms
• Climate
– El Nino
– Climate Change
Hey! Where’s all the ice gone?
There’s a hole in the sky! (TD 1)
A large hole in the ozone
layer was detected in
Previous to this discovery,
the US FDA phased out
the use of CFCs in
aerosols in 1976, based
on the experimental
work by F. Sherwood
Rowland and Mario
What’s the big deal?
• Ozone depletion is a big deal!
• Follow “Farley” as he learns more about ozone
• Also go to
ml to learn more about the Montreal Protocol,
one of the international agreements on ozone
layer protection, as well as others
• Create “flash cards” for the ozone agreements! 102
To fry or not to fry?
UV Radiation can be quite harmful to living
Go to
4139 to watch the animation and
for more information regarding UV
Radiation and the