TROPICS: insolation high year round, high sun angle and ~
constant duration
GEO 101, February 6, 2014
Finish insolation variation
Global environmental issues associated with insolation
MID-LATITUDES: insolation highest at summer solstice,
higher sun angle and longer day, lowest at winter solstice
due to low angle and short day
Poles: insolation highest at summer solstice due to 24 hour
duration low angle sun, none at winter solstice
Total annual insolation decreases as latitude increases
Seasonality (difference between winter and summer)
increases as latitude increases
Insolation on the June Solstice
Comparison between top of atmosphere and Earth surface
Global average annual energy balance
Duration factor
23.5°N
Surplus
Top of atmosphere
Mid-High latitudes
N. Pole
Equator
Deficit
Tropics
San Francisco
St. Louis
Washington DC
90°N
Chart monthly insolation at the North Pole
70°N
0
4
8
12
16
20
24
28
32
36
40
60°N
At top of the atmosphere
50°N
40°N
30°N
20°N
10°N
00°N
10°S
20°S
Megajoules/m2/day
80°N
4
8
12
44
20
24
28
16
32
36
20
24
8
12
16
40
36
32
28
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
0
0
20
39
44
40
24
1
0
0
0
90° sun
elevation
30°S
40°S
50°S
60°S
44
70°S
80°S
90°S
48
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1
50
Chart of monthly insolation at the North Pole
(dark bars = N.P., light are Equator for reference)
Chart monthly insolation at the South Pole
45
40
40
35
32
36
30
24
28 20
16
16
12
12
24
32
20 28
40
36
44
25
44
20
15
10
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
5
44
Jan Feb Mar
Apr May Jun
Jul
Aug Sep Oct
25
6
0
0
0
0
0
0
17
37
49
Nov Dec
Example only, do not use your sheet for this demo. problem.
Class assignment: if your last name begins with
A-B, do 80°N and 10°S
90° S
C-D, do 70°N and 20°S
E-H, do 60°N and 30°S
I-L, do 50°N and 40°S
M, do 40°N and 50°S
N-Q, do 30°N and 60°S
R-T, do 20°N and 70°S
U-Z, do 10°N and 80°S
Graphs will be due on Tuesday
Ultraviolet
Visible
light
Shortwave
infrared
Thermal
infrared
Two global environmental issues related to interaction of
atmospheric gases, insolation, and outgoing Earth radiation
From sun to
earth
Ozone
Greenhouse gases
From earth
to space
Incoming
shortwave
radiation
9%
41%
Outgoing
longwave
radiation
50%
2
Earth’s atmosphere is
unique: not at chemical
equilibrium (entropy).
Highly reactive
atmosphere reveals life.
For greenhouse warming and ozone
depletion, be able to explain:
•basics of how it works
•problem
O2
•causes of the problem
O3
•consequences
•possible solutions
N2
Ozone depletion
What is ozone?
Naturally occurring form of oxygen with 3
oxygen atoms in molecule instead of usual two.
O2 is what we need to breathe
O3 is a highly reactive gas
(like breathing chlorox fumes)
Life (as we know it) evolved under ozone layer protection
Land plants
Oxygen
revolution
Photosynthetic bacteria
Where is ozone?
~400 mya
90% of O3 found in
stratosphere
~2.4 bya
good ozone: blocks
UV radiation
~3.7 bya
10% of O3 near
Earth’s surface
Carbon
dioxide
Methane
Single cell organisms
Sulfur
dioxide
bad ozone: toxic to
life
Nitrogen
compounds
Earth formed
~4.6 bya
3
Man-made chemicals that destroy ozone
Normal equilibrium
•CFCs (chlorofluorocarbons), HCFCs: refrigerants,
foam blowing agents, aerosol propellants
O2 + UV  O + O
•Halons: old fire extinguishers
O2 + O  O3
•Carbon tetrachloride: solvent
O3 + UV  O2 + O
•Methyl chloroform: solvent, aerosols, cleaners,
(labeled as 1,1,1-trichloroethane)
Most O3 produced in tropical stratosphere
and transported poleward
•Methyl bromide: pesticide (soil fumigant) used
heavily on tomatoes and strawberries
(Banned in 2005)
Manmade chemicals interfere with equilibrium
All are long lasting
Ozone Hole Area in million km2
Global environmental problem
30.0
Identified in 1980s
25.0
Stratospheric O3 concentrations decreasing
20.0
Most noticeable in Antarctica
15.0
10.0
5.0
0.0
1975
1980
1985
1990
1995
2000
2005
2010
2015
TOMS = Total Ozone Mapping Spectrometer
OMI = Ozone Monitoring Instrument
How do CFCs destroy ozone?
How do CFCs destroy ozone?
F
Cl
O
C
Cl
Cl
O
Cl
Ultraviolet radiation
strikes a CFC
molecule
...and causes a chlorine
atom to break away
O
Chlorine atom collides
with an ozone molecule
...creates molecule of
regular oxygen and
chlorine monoxide
4
How do CFCs destroy ozone?
O
In winter, chlorine attaches to ice clouds in
stratosphere above pole. This keeps ozone-depleting
chlorine “locked up”
When ice melts in spring (September in Antarctica),
chlorine is freed and attacks O3  “hole”
Cl
chlorine is
freed to
react again
O
http://ozonewatch.gsfc.nasa.gov/
Free oxygen atom
collides with chlorine
monoxide
...yields a molecule of
regular oxygen and a
free chlorine atom
Globally, what’s being done about it?
What’s so
bad about it?
Montreal Protocol, 1987
1% ozone loss ~
World production
5-7% increase in
skin cancer
World production
Cataracts
Immune system
suppression
Inhibits plant
growth
Montreal Protocol relatively successful because
You personally can:
1. Problem obviously man-made
2. Scientists agreed on cause and solution
3. No major country’s economy based on CFCs
•FIX leaky auto air conditioners
(#1 CFC, HCFC, HFC source in US)
5
What are greenhouse gases?
Greenhouse warming
Range is from blue (low) to red (high)
What are anthopogenic greenhouse gases?
Approximate percent responsibility for problem
How does it work?
Halocarbons
GG
http://www.esrl.noaa.gov/gmd/ccgg/trends/co2_data_mlo.html
http://cdiac.ornl.gov/trends/co2/jubany.html
6
Are current CO2 levels that unusual?
Global Land and Ocean Temperature Anomalies
1880 - present
Ice core records
http://www.ncdc.noaa.gov/cag/time-series/global
http://www.ncdc.noaa.gov/cag/time-series/global
Causes of CO2 concentration increase
Deforestation
Causes of CO2 concentration increase
What are fossil fuels?
Burning of fossil fuels
Liquid
Solid
Gas
7
Top Ten CO2 emitters in 2008 (million metric tons of carbon/ year)
2008 per capita fossil-fuel CO2 emission rates. expressed in
metric tons of carbon.
http://www.ucsusa.org/global_warming/science_and_i
mpacts/science/each-countrys-share-of-co2.html
Consequences may be
• Higher sea levels due to ocean expansion
and ice melting (inundation of island
nations)
What’s being done globally?
Kyoto Protocol: 1997 : agreement to reduce
greenhouse gas emissions by % of 1990 levels.
• More intense storms
• Disruption of agriculture
Entered into force on February 16, 2005
• Extinctions
• Spread of tropical diseases
Kyoto Protocol not as successful because
1. Problem itself highly debated
2. Developed countries’ economies based on fossil fuels
3. Developing countries’ forests are source of income
4. China’s energy needs met by coal
United States never ratified protocol
What can you do personally ?
Conserve energy
Drive fuel efficient vehicle
Insulate home
Recycle (saves energy)
on-campus paper and aluminum
Much more expensive to implement Kyoto Protocol
Plant trees
8
9