Earth’s Climate System &
Factors Affecting Climate
Earth’s Atmosphere…
► The
envelope of gases
surrounding Earth, also
consists of microscopic
dust particles that act as
condensation nucleii to
allow for condensation &
cloud formation
Layers of Earth’s Atmosphere…
► Earth’s
atmosphere is layered according to
density
► Troposphere, Stratosphere, Mesosphere,
Thermosphere, Exosphere all have different
properties, conditions
Composition of Atmosphere:




78% Nitrogen
21% Oxygen
0.9% Argon
0.1% Water Vapor, Carbon Dioxide, Methane,
Nitrogen Oxides, Ozone, etc.
► Although
the last group is only 0.1%, these are
critical to life on Earth!
► Earth’s Greenhouse Effect is caused mostly by
the last group!
How is the Earth Heated?
► By
the Sun of course!
► Incoming Solar Radiation = Insolation
 Most insolation reaching Earth’s surface is in the
form of visible light rays!
 Lesser amounts of X-rays, gamma rays, radio
waves, infrared, ultraviolet make it to Earth, but are
typically intercepted by gases in Earth’s upper
atmosphere, or shielded by magnetic field
How is the Earth Heated?
Earth’s surface is heated unequally by the Sun
► Heat is transferred from warmer areas to colder areas in
one of three ways:
1. Conduction = heat transfer through molecular contact; When 2
objects are touching on another, heat is transferred from the
hotter to the colder until equilibrium is reached
2. Convection = the circular flow of heat due to density
differences
►
 Warm air rises (less dense) while cold air sinks (more dense)
3.
Radiation = energy moving in the form of waves coming from
the Sun
 Incoming Solar Radiation = INSOLATION
 Most insolation that actually reaches Earth’s surface is in the form of
visible light rays (4.0 x 10-5 to 7.0 x 10-5cm)
Fate of Incoming Solar Radiation…
How is the Earth Heated?
► Earth’s Greenhouse Effect:
► Earth is heated when visible light
rays strike the
surface, and energy is absorbed and then re-radiated
as infrared heat
► Incoming visible light radiation is a SHORTER
wavelength than outgoing infrared radiation.
 Gases in atmosphere are transparent to incoming solar
radiation (mostly visible light) & allow it to reach Earth’s
surface
 Visible light strikes earth’s surface, which heats up and emits
longer wavelengths of energy in the form of infrared
radiation (called terrestrial radiation)
 Gases in atmosphere are NOT transparent to outgoing
infrared rays, and some of it is re-directed back towards
Earth’s surface, thereby heating the troposphere!
Sun’s Electromagnetic Spectrum
Draw Earth’s Greenhouse Effect!
Albedo: the “reflectivity” of a surface
► Earth’s
surface varies greatly in the amount of
insolation it can absorb
 High albedo (very reflective, non-absorbing
surfaces) include ice sheets, snow
 Low albedo surfaces include pavement, buildings,
etc.
 Forests and the ocean have low albedo values
(perhaps only 5% reflectivity), so they can absorb
lots of solar energy!
Natural Physical Factors Affecting Climate:
1. Latitude:
•
near equator is warm, near poles is cold, because at
equator the Sun strikes Earth at a higher angle of
insolation, at poles Sun strikes Earth at a lower angle
of insolation
Natural Physical Factors Affecting Climate:
1. Latitude…continued:
•
Seasons on Earth are determined by latitude and
angle of insolation at various times throughout the
year, and are caused by:
►
►
►
Tilt of Earth’s axis
Earth’s revolution around the Sun
Parallelism of Earth’s axis
Seasons on Earth…
Yearly Daylight
Analemma for
Poughkeepsie,
NY
Yearly Daylight
Analemma for
Quito, Ecuador
Yearly Daylight
Analemma for
Melbourne, Australia
Yearly Daylight
Analemma for
Barrow, Alaska
Yearly Daylight
Analemma for
the Geographic
North Pole!
Natural Physical Factors Affecting Climate:
2.
Proximity to a large
body of water (ocean or
large lake):
► Water has a high
specific heat, so the
ocean does NOT
heat up or cool
down easily, and
therefore helps to
regulate
temperatures of
nearby coastal
areas
Natural Physical Factors Affecting Climate:
3.
►
►
Nearness to mountains:
Higher elevations have colder avg.
temperatures, longer snowpack, etc.
Orographic effect: (rainshadow)


Windward side of mountains force air to rise,
expand, cool, and cause water vapor to condense,
forming clouds and abundant rainfall
Leeward side of mountains experience dry
conditions as air sinks…called the “rainshadow”
side.
Draw the Windward & Leeward Sides of a Mountain Range
Orographic (Mountain) Effect:
Natural Physical Factors Affecting Climate:
Global Wind Circulation
Patterns
Due to the unequal heating
of Earth’s surface, there are
major temperature zones
on Earth (equator is warm,
poles are cold)
4.
Global Wind & Pressure Belts…
► Temperature
differences create pressure
differences, which cause the wind to blow
from areas of high pressure toward areas of
low pressure!
► Global wind belts are formed as major
convection cells, helping to distribute heat
more equally across globe!
► Overall weather and climate patterns are
impacted by what global wind belt influences a
particular area.
Earth’s major global wind and pressure belts
Natural Physical Factors Affecting Climate:
5.
Ocean Circulation Patterns:
•
•
•
•
Prevailing wind belts create mass movements of
ocean water (currents)
Circular ocean currents are called “gyres”
Ocean currents are also influenced by the Coriolis
effect, and tend to circulate clockwise in the N.
hemisphere, and counterclockwise in the S.
hemisphere
Ocean currents are forced to move around major
landmasses (continents and islands)
Earth’s Major Ocean Currents
Global Ocean Currents
• A warm ocean current approaching a coastline will
likely keep nearby temperatures warmer, while a
cooler ocean current approaching a coastline will
likely keep nearby temperatures cooler than they
would otherwise be.
Cold vs. Warm Ocean Currents
Natural Physical Factors Affecting Climate:
6.
Ocean-Atmosphere Interactions
•
•
The ocean interacts with the atmosphere to
dramatically influence climate patterns worldwide
El Nino & La Nina can impact global climate in any
given year
El Nino & La Nina Events
►
What is an “El Nino” or a “La
Nina”?
 An El Niño/La Nina event is an
oscillation of the ocean-atmosphere
system in the tropical Pacific
having important consequences for
weather around the globe.
 This interaction is sometimes called
ENSO = El Nino/Southern Oscillation
 El Nino & La Nina are the changes
that occur in the ocean sea surface
temperatures
 The “Southern Oscillation” refers to
the atmospheric changes occurring,
specifically the monthly or seasonal
fluctuations in the air pressure
difference between Tahiti and
Darwin, Australia.
El Nino & La Nina
cause major world
wide climate
consequences: (El
Nino Climate
Consequences Shown
Here)
Normal Conditions in the Tropical
Pacific Ocean…
Normal Conditions in the Tropical
Pacific Ocean…
►
►
►
Typically, strong trade winds (from
both North and South), meet up
and blow ocean water AWAY from
coast of Peru, pushing warm water
toward the western tropical Pacific
(near Australia)
This allows cold water upwelling
off the coast to replace the warm
water that has departed.
Fishing industry benefits greatly,
because cold water upwelling
brings nutrients to supply base of
elaborate food web!
Normal Conditions in the Tropical Pacific Ocean…
El Nino Conditions
► During
El Niño, the
trade winds weaken in
the central and
western Pacific leading
to a warming of the
surface ocean waters
in the eastern Pacific
(typically off the coast
of Peru).
El Nino
► The
deeper thermocline results in less
upwelling, lack of nutrients, and a loss of
productivity and fish!
► The deeper thermocline impacts climate worldwide!
El Nino Conditions…
Recognizing El Nino…
► El
Nino can be identified
by monitoring Sea
Surface Temperatures in
the tropical Pacific
ocean, using moored
buoys (see diagram).
► Buoys send data
continuously to satellite,
which transmits back to
NOAA computers
NORMAL CONDITIONS
EL NINO CONDITIONS
El Nino
Impacts
La Nina Conditions:
► During
La Nina, trade winds strengthen,
thereby more effectively pushing warm surface
water westward, away from the coast of Peru,
and allowing for increased cold water upwelling
off the coast, enhancing the productivity and
fishing habitats.
La Nina Conditions
A look at all three conditions…
Where did the name come from?
► El
Niño was originally recognized by fisherman
off the coast of South America as the
appearance of unusually warm water in the
Pacific ocean, occurring near the beginning of
the year.
► El Niño means The Little Boy or Christ child in
Spanish. This name was used for the tendency
of the phenomenon to arrive around Christmas.
► La Niña means The Little Girl.
La Nina
Impacts
…
Animated SST Sequence: ENSO
Most Recent ENSO Index
Current Observations of Climate
► Today,
a wide variety of instruments have been
deployed to continuously measure a large
number of climate factors including:
 Air temperature
 Sea surface temperature
 Greenhouse Trace Gas concentrations (CO2, CH4,
O3, NO, NO2, etc.
 Response of plants (budding times, size, etc.)
 Response of animals (changes in range, timing of
reproduction, etc.)
Current Observations of Climate
Climate Change:
► Due to human influence, the Earth’s climate
systems are changing as a response to the
increased greenhouse gases in the atmosphere
caused by the burning of fossil fuels and
deforestation of the planet.
Methods Used to Gather Current Data:
► Weather
monitoring
stations
► Weather balloons
 These measure air
pressure, humidity, wind
direction, wind speed,
temperature, dew point
temperature on a daily
basis
 Some now also
monitoring atmospheric
gas content
Methods Used to Gather Current Data:
► Ocean
surface buoys
 Measure sea surface
temps., ocean currents
direction and speed, etc.
► Data
from ships at sea
► Satellites orbiting Earth
► Field observations from
ecosystem studies
Effects of Global Warming…What Have We
Found So Far?
► An
overall 1°C increase (about 2°F) over the
past 100 years.
► Sea level has risen consistently since the end of
the last ice age (past 18,000 years or so)
► Antarctic & Greenland ice core data reveal that
Earth’s current warming trend outpaces any
natural warming trends that have occurred in
the past, and are therefore likely the result of
human influences (burning fossil fuels &
deforestation).
Vostok
Ice
Core
Data:
Effects of Global Warming…What May Happen?
►
►
The IPCC = The Intergovernmental Panel on Climate Change
produces an annual report that outlines new findings, analyzes
real-time data, and makes projections about future climate
based on various computer models
The enhanced greenhouse effect and the subsequent warming
of the Earth has several major implications for the planet,
including:
 Melting of glaciers and sea level rise (some rise due to thermal
expansion as ocean warms, some due to additional water in oceans from
melting continental glaciers)
 Changes in precipitation patterns
 Effects on organisms
 Effects on human health
 Effects on agriculture
 Other potential “surprises”, such as the shutting down of the N. Atlantic
ocean conveyor
Tree Ring Studies…
Effects of Global Warming…What Have We Found?
► Melting
Ice
Arctic Sea Ice Change…2005 to 2007
2007 Arctic Ice Video
Effects of Global Warming…What Have We Found?
► Sea
Level
Rise
(Animation)
Effects of Global Warming…What Have We Found?
Changes in Precipitation & More Extreme Weather Events
Effects of Global Warming…What Have We
Found?
► Certain
plants are responding to warmer
temperatures by:
 Showing signs of stress (disease)
 Earlier average budding dates in spring
 Shifting their ranges
Leafing Dates of Oak Trees (SE England)
Possible Effects of Global Warming on
Beech Trees
Beech
Future
range
Overlap
Present
range
Fig. 16-11, p. 377
What have we found lately?
► Certain
animals are
responding to
warmer
temperatures by:
 Becoming
endangered or
threatened as they
lose habitat (Polar
Bears, Amphibians,
etc.)
 Shifting their ranges
 Changing their
feeding habits, etc.
What’s happening in the oceans?
► Thermohaline
Circulation = known as the
“oceanic conveyor belt”…it is the mass
movement of ocean water by convection as
heated, less dense water moves across surface
(usually from equator toward poles), while
colder, more saline, denser waters move at
depth (usually back towards equator)
 This circulation is largely responsible for the redistribution of heat across the planet
Thermohaline Circulation…
Thermohaline Circulation…what’s
happening?
 the overall
movement of
water in the
North Atlantic
appears to be
slowing down
with the influx
of fresh water
from the
Arctic…
Thermohaline Circulation…what’s
happening?
► Shutting
Down of the N. Atlantic Conveyor Has
Huge Climate Implications:
 May actually plunge Europe into an “ice age”, since
the Gulf Stream may not continue to bring warmth
 Could drastically alter marine ecosystems, impacting
fisheries worldwide
 May trigger more severe climatic events such as
hurricanes where water becomes excessively
heated
 ???? Remember…we are performing an experiement
on ourselves!
Other oceanic changes…
► Sea
surface temperatures are getting slightly
higher...but it takes a LOT of heat energy to increase
temps of oceans even slightly (recall water’s high
specific heat)
Other oceanic changes…
► Acidification
of the oceans…pH values have
decreased by approximately 0.1 unit in surface
waters already due to oceanic uptake of
anthropogenic CO2 (NOAA)
► pH values may go down another 0.4 units with
expected anthropogenic increases in CO2
(NOAA)
► Lower pH values change the carbonate
chemistry of the water…and in effect begins to
dissolve the shells of marine organisms!
Effects of Global Warming…what’s
next?
► IPCC = Intergovernmental Panel on Climate Change
predicts that temperatures may increase anywhere
from 1.4° to 5.8 °C in the next century!
► Warming is most extreme in the Arctic, where record
low ice levels have been reported in the past year!
► Crop failures, desertification, and the increased
incidence of insect-borne diseases are predicted or are
already present!
► Emerging diseases may also be linked to warmer
temperatures…
► Economic failure in some areas will impact the entire
world…it is a world economy!
Risk of Malaria Transmission Will
Increase due to Global Warming…
North & South
America
Consequences
Consequences for
the rest of the
world
More heat, more pollen, more asthma,
more ozone…
Annual Mean Water Temperature at Poughkeepsie
14.0
13.5
Temperature
13.0
12.5
12.0
11.5
Sen (Q=.017; p<.001)
11.0
1940
1950
1960
1970
1980
Year
1990
2000
2010
What’s Causing The Enhanced Greenhouse Effect and
“Global Warming”?...HUMANS! (anthropogenic factors)
► Increases
in greenhouse trace gases (GTG’s)
have been primarily due to human activities,
which are called anthropogenic effects.
► Greenhouse trace gases, include H2O (water
vapor) CO2 (carbon dioxide), CH4 (methane),
NxOx (nitrous oxides), O3 (ozone), and
halocarbons like CFC’s (chlorofluorocarbons).