Earths Radiation

1
Earths Radiation Energy Budget
Science Concepts Reflection and
Scattering Absorption Transmission Reflection
and Scattering Scattering-Wavelength
Relationship Atmospheric Gases Clouds Particu
lates Absorption Atmospheric Gases Clouds Transm
ission Atmospheric Gases Clouds
Solar-Terrestrial Radiation Relationships Intera
ctions Simple Radiation Budget Shortwave
Radiation Interaction with Atmosphere Blue
Skies Milky Skies Red Sunsets Shortwave
Radiation Budget
The Earth System (Kump, Kastin Crane) Chap.
3 (pp. 50-51) Chap. 4 (pp. 58-59)
2
Earths Radiation Budget
What happens to incident solar radiation as it
interacts with the Earths atmosphere?
What are the three things that can happen to
radiation when it interacts with an object?
Science quotes of 5th and 6th graders - Most
books now say our sun is a star. But it still
knows how to change back into a sun in the
daytime.
http//www.cmdl.noaa.gov/ infodata/faq_cat-1.html
3
Radiation
What happens to radiation when it interacts with
an object? Transmission - Energy passes
through material basically unchanged, i.e.,
unchanged energy and wavelength - Note
direction may be bent by the process of
refraction Reflection or scattering - Both
redirect radiation without changing the energy
or wavelength - Scattering redirects
radiation in all directions, frequently has
more intensity in some directions than
other - Reflection redirects radiation in a
specific direction Absorption - Causes
molecules to increase their kinetic energy, e.g.,
increase their temperature
http//rst.gsfc.nasa.gov/Intro/ Part2_3html.html
4
Solar or Shortwave Radiation
Solar Radiation and the Earths Atmosphere
(Cont) Why is the sky blue? Why is the
cloud white?
5
Solar or Shortwave Radiation
Solar Radiation and the Earths Atmosphere
(Cont) Why are sunsets and sunrises red?
6
Solar or Shortwave Radiation
Solar Radiation and the Earths Atmosphere
(Cont) Why is the Earth white and
blue? Why is the sky black? Apollo 11 Earth
View Earthrise viewed from lunar orbit prior
to landing
http//www.hq.nasa.gov/office/pao/History/ alsj/a1
1/AS11-44-6551.jpg
7
Solar or Shortwave Radiation
Solar Radiation and the Earths Atmosphere
(Cont) Answer from 1/31/05 Parade newspaper
insert The light that travels from the Sun to
the Earth contains every color there is. But the
Earths air lets the blue light shine through the
best. Sometimes, when the air is very wet after
it rains, it makes a rainbow, with all the
colors. At sunset, red light can shine through
as well. Do you agree with this answer?
1/31/05 Parade newspaper insert, pp. 17-18.
8
Solar or Shortwave Radiation
Scattering by Atmospheric Gases Scattering
redirects energy in all directions Scattering
depends on the size of objects doing scattering
compared to the wavelength of incident
electromagnetic radiation - For small
objects, i.e., atmospheric gas molecules that
are about 1000 times smaller than wavelengths
of visible light gt Intensity of scattering
(I), Rayleigh scattering, is inversely related
to the wavelength (?) of the radiation to the
fourth power, i.e., I (scattering) ? 1 /
?4 Shorter wavelengths are scattered more
than longer wavelengths Note If the
wavelength (?) of the incident radiation is
halved, then the scattered energy will 16 more
http//ww2010.atmos.uiuc.edu/(Gh)/ guides/mtr/opt/
mch/sct.rxml
9
Solar or Shortwave Radiation
Scattering by Atmospheric Gases
(Cont) Scattering depends on the size of
objects doing scattering (Cont) - For small
objects, i.e., atmospheric gases
(Cont) gt Examples ? (Violet) 0.425 ?m, ?
(Blue) 0.465 ?m and ? (Red) 0.65 ?m I
(Violet) ? (Red) 4 ( 0.65 ) 4 4.47
I (Red) ? (Violet) 4 ( 0.425 ) 4 Violet
scatters 4.47 times more than red Blue scatters
3.76 times more than red gt So why isnt
the sky violet? Violet has an even shorter
wavelength than blue, thus is scattered even
more than blue
10
Solar or Shortwave Radiation
Scattering by Atmospheric Gases
(Cont) Scattering depends on the size of
objects doing scattering (Cont) - For small
objects, i.e., atmospheric gases
(Cont) gt So why isnt the
sky violet? (Cont) Solar
radiation has more energy in
blue wavelengths than in violet
Wehrli, C., 1985 Extraterrestrial Solar
Spectrum, Publication no. 615, Physikalisch-Meteor
ologisches Observatorium World Radiation Center
(PMO/WRC) Davos Dorf, Switzerland.
11
Solar or Shortwave Radiation
http//www.croydonastro.org.uk/ Vision7-mod3.pdf
Scattering by Atmospheric Gases
(Cont) Scattering depends on the size of
objects doing scattering (Cont) - For small
objects (Cont) gt So why isnt the sky
violet? (Cont) Eye has two types of
receptors, cones and rods Cones -
color vision, three kinds yellow-green (564
?m), green (534 ?m) and blue-violet
(420 ?m) (LMS cones) Typically 64 of
cones are yellow-sensitive, 32
green- sensitive and 2 blue- sensitive
Blue cones are most sensitive
Resulting eye sensitivity for cones and
rods - note rapid decrease in sensitivity
in violet
http//www.darksky.org/VisionSeries/vs2-4.html
12
Solar or Shortwave Radiation
http//www.darksky.org/ VisionSeries/vs2-4.html
Scattering by Atmospheric Gases
(Cont) Scattering depends on the size of
object doing the scattering (Cont) - For
small objects (Cont) gt So why isnt the
sky violet? (Cont) Rods More cones
than rods More sensitive than cones
Not as color sensitive (only one type)
Function in less intense light than cones, helps
with night vision gt Experiment - Look at a
rose in full moonlight, the flower is brightly
lit and may even cast a shadow, but the red
is gone, replaced by shades of gray. In fact,
the whole landscape is that way. Why? -
Because of low light intensity, you are mainly
seeing with the rods which see
monochromatically, i.e., little color
http//science.nasa.gov/headlines/y2006/ 28sep_str
angemoonlight.htm?list159742
13
Solar or Shortwave Radiation
Scattering by Atmospheric Gases (Cont)
Apollo 11 Earth View - No scattering of
light at the moons surface because the
moon has no atmosphere, i.e., no gas
molecules
http//www.hq.nasa.gov/office/pao/History/ alsj/a1
1/AS11-44-6551.jpg
14
Solar or Shortwave Radiation
Scattering by Atmospheric Gases (Cont) gt Red
sunrises and sunsets
Axis of Rotation
Sunset
Solar Rays
Penetration Depth
Solar Rays
Penetration Depth
Atmospheric Layer
15
Solar or Shortwave Radiation
Scattering by Atmospheric Gases (Cont) Lunar
Eclipse - Note Moon goes from bluish white
to reddish as the lunar eclipse proceeds
and then back to bluish white - Result of
solar radiation of the Earths atmosphere
scattering blue more than red light
http//science.nasa.gov/headlines/y2000/ ast02feb
5F1.htm
16
Solar or Shortwave Radiation
gt The moon is not always at the same
distance from the Earth and its closer
proximity causes it to look much larger gt We
are looking horizontally through a thicker layer
of the atmosphere, rather than straight up
through a thinner layer and thus the image of
the moon is magnified gt It is simply an
illusion - the image is merely perceived as
bigger when the moon is near the
horizon How can we test these explanations?
Lets think about how plausible each
explanation might be and how we might prove or
disprove each one.

An Aside Why does the Moon appear so large
when it is near the horizon? - What are some
plausible-sounding explanations?
17
Solar or Shortwave Radiation

An Aside (Cont) The moon is not always at the
same distance from the Earth and its closer
proximity causes it to look much larger - Does
the moon get farther away from the Earth as it
rises?
18
Solar or Shortwave Radiation
An Aside (Cont) It is simply an illusion
the image is merely perceived as bigger when
the moon is near the horizon Try the following
experiment - Try the following experiment -
Look at the moon through a cardboard tube
(like those found inside rolls of paper
towels). Viewing the moon this way isolates it
from the surrounding reference frame of trees and
houses. gt Stand the cardboard tube on end and
trace a circle around the base of the tube
onto a piece of paper gt Label the circle with
the time of your observation gt Make your first
observation of the moon when it is near the
horizon. Look at the moon through the
cardboard tube and then make a sketch in the
circle you traced showing how much of the tube is
filled by the image of the moon gt Repeat
the above steps every hour or two for about six
hours (when the moon is overhead)
gt Compare your sketches and draw conclusions
19
Solar or Shortwave Radiation
http//news.bbc.co.uk/2/hi/uk_news/magazine/461906
3.stm
An Aside (Cont) Optical illusions - Are the
yellow lines the same length?
20
Solar or Shortwave Radiation
Absorption by Atmospheric Gases Ozone and
oxygen absorbs much of the ultraviolet in the
upper atmosphere Water vapor and carbon
dioxide absorb some of the near infrared
21
Solar or Shortwave Radiation
Absorption by Atmospheric Gases
(Cont) Atmospheric absorption solar radiation
22
Solar or Shortwave Radiation
Absorption by Atmospheric Gases (Cont) The
atmosphere absorbs, transmits or reflects solar
radiation
http//en.wikipedia.org/wiki/ImageMODIS_ATM_solar
_irradiance.jpg
23
Solar or Shortwave Radiation
Interaction with Clouds Clouds, (typical
droplets are about 50 times larger than the
wavelengths of visible light) when present they
reflect, absorb and transmit radiation. - Cloud
s are very good reflectors of solar radiation.
Intensity of reflection related to the cloud
depth Cloud depth (m) Albedo
() 100 75 1000 85 - Clouds are not
very good absorbers of solar radiation. Amount of
absorption related to the cloud
depth Cloud depth (m) Absorption
() 100 5 1000 10
Science quotes of 5th and 6th graders - I am
not sure how clouds get formed. But the clouds
know how to do it, and that is the important
thing.
24
Solar or Shortwave Radiation
Interaction with Particulates Atmospheric
particulates scatter radiation - For larger
objects (dust, pollution and droplets) intensity
of scattering is equal for all wavelengths,
called Mie scattering. Causes haze, milky color
sky. Increases albedo. Example - Great Smoky
Mountains Clear Day Hazy Day
http//www.epa.gov/oar/vissibility/w
hat.html Particles such as sulfates, scatter more
light, particularly during humid conditions.
Natural sources of haze-causing pollutants
include dust, and soot from wildfires. Manmade
sources include vehicles, electric utility and
industrial fuel burning, and manufacturing. Some
haze-causing particles are formed from gases
emitted many miles upwind.
25
Solar or Shortwave Radiation
What do we mean when we say Once in a blue
moon? According to modern folklore, a Blue
Moon is the second full moon in a calendar
month. Usually months have only one full moon,
but occasionally a second one sneaks
in. - Full moons are separated by 29 days,
while most months are 30 or 31 days long so
it is possible to fit two full moons in a single
month - This happens every two and a half
years, on average. gt For example July 2004
had one full moon on 2 July and another on 31
July which was by definition a Blue Moon Truly
blue colored Moons can be cause by atmospheric
particulates about 1 micron (near the size of
red light scatter red light, while allowing other
colors to pass) in size, for example, volcanic
ash or forest fires - Blue Moons occurred in
1883 and for years after when Krakato erupted
- Other examples include gt El Chichon (1983)
in Mexico gt Mt. St. Helens (1980) in
U.S. gt Mount Pinatubo (1991) in Philippines
http//science.nasa.gov/headlines/ y2004/07jul_blu
emoon.htm?list104690
26
Solar or Shortwave Radiation
Summary of Interaction with the Earths
Atmosphere Most (55) visible radiation or
energy reaches the Earths surface.
Air here refers to the gas molecules and
particulates
27
Solar or Shortwave Radiation
Surface Albedo Uses MODIS data composited over
a 16-day period, from April 7-22, 2002 White
indicates no data and no albedo data are provided
over oceans
Note This is surface albedo Where are the
regions with the highest albedo? What type of
surfaces do these regions have?
http//earthobservatory.nasa.gov/Newsroom/ NasaNew
s/2002/200207099816.html
28
Solar or Shortwave Radiation
Reflected Solar Radiation Reflected Solar
Radiation (W/m2) Winter solstice, 22
December 2004 Summer solstice, 20 June
2005
Note These images are top-of-atmosphere
reflected energy as seen by satellite, not
surface only reflected energy What dominates the
albedo in these images?
http//earthobservatory.nasa.gov/Newsroom/ NewImag
es/images.php3?img_id17130
29
Earths Radiation Energy Budget
Shortwave Radiation Interaction with Earths
Surface Surface Types Soil Moisture and
Vegetative Effects Albedo Water Water and
Land Differences
Science Concepts Reflection and
Scattering Absorption Energy Versus
Temperature Specific Heat Absorption Specific
Heat Mixing Evaporation
30
Solar Radiation at the Earth Surface
What happens to solar radiation as it interacts
with the Earths surface? Absorbed or
reflected - Examples Albedo
or Material Absorption Reflection Fresh
Snow 25-5 75-95 Old Snow 60-30 40-70 S
ea Ice 70-60 30-40 Desert 75-70 25-30
Glacier Ice 80-60 20-40 Grass 84-74 16-26
Crops 85-75 15-25 Deciduous
Forest 85-80 15-20 Tundra 85-80 15-20
Soil 85 15 Water (Low Sun) 90-0 10-100
Asphalt 94 6 Coniferous
Forest 95-85 5-15 Water (High
Sun) 97-90 3-10 albedo of water depends on
the solar angle and sea surface roughness
(daily average given). Low angle more albedo.
31
Solar Radiation at the Earth Surface
Interaction with the Earths Surface What is
wrong with this statement? Albedo was
technically defined as the ratio of
electromagnetic energy reflected by a surface
to the amount of energy incident upon it. In
terms of the visible spectrum. it was a measure
of how shiny a surface was. A river had a
high albedo, since water reflected most of the
sunlight striking it. Vegetation absorbed
light, and therefore had a low albedo. Cong
o by Michael Crichton, p. 69.
http//www.ucar.edu/communications/ CCSM/overview.
html
32
Solar Radiation at the Earth Surface
Specific Heat Capacity Specific heat (heat
capacity) is the amount of heat per unit mass
required to raise the temperature by one degree
Kelvin or Celsius - Coefficient which is
related to how efficiently a material converts
energy into sensible temperature change (
Temperature change of object ) ( Energy
absorbed or given up by object )
( Objects specific
heat Mass of object ) Specific Heat
Capacity Specific Heat Capacity
Substance cal / (g K) Substance cal / (g
K) Water 1.00 Ice (_at_ 0C) 0.48 Asphalt 0.22
Brick 0.20 Aluminum 0.22 Concrete 0.21 Copp
er 0.09 Glass (Typical) 0.20 Gold 0.03
Granite 0.19 Iron 0.11 Sand 0.20 Soil
(Dry) 0.19 Soil (Typical) 0.25 Soil
(Wet) 0.35 Wood (Typical) 0.40 Dry air (_at_
sea-level pressure) 0.24 Saturated air (_at_
sea-level pressure) 0.25
33
Solar Radiation at the Earth Surface
Interaction with the Earths Surface
(Cont) Example Given one gram of material,
what will be the temperature change if one
calorie of electromagnetic energy impinges on the
material? - Water - 90 absorbed, thus 0.9 cal
of heat available to warm the water Change in
temperature Energy / ( Mass Specific
Heat ) 0.9 cal / ( 1 g 1 cal / g -C
) 0.9C - Soil - 85 absorbed, 0.85 cal
of heat available to warm the soil Change in
temperature wet or
dry 0.85 cal / ( 1 g 0.35 or 0.19 cal /
g -C ) 2.43 or 4.47C - Asphalt - 94
absorbed, 0.94 cal of heat available to warm the
asphalt Change in temperature 0.94
cal / ( 1 g 0.22 cal / g -C ) 4.27C
34
Solar Radiation at the Earth Surface
Interaction with the Earths Surface
(Cont) Why does land becomes hotter than
water during the day? - Water absorbs energy in
a deeper layer, i.e., more mass because it is
more transparent - Water has higher specific
heat - Water is a fluid and can mix the energy
throughout a deeper layer - More of the energy
is used to evaporate water over water
surfaces than over land surfaces Daily
temperature range
Temperature Range (F)
10
20
30
40
50
4
Soil
8
Inches
Deep Circulating Pool
12
Pool 16" Deep
16
35
Earths Radiation Energy Budget
Science Concepts Conduction Convection Sensible
Heat Latent Heat Radiation
Surface Budget Surface Energy
Budget Fluxes Bowen Ratio
36
Earths Surface Energy Budget
What happens to the energy absorbed at the
Earths surface? Conduction - Into
ground Convection - Important cause of
weather - About 20 of energy transfer - Two
types gt Sensible (Temperature change) - about
25 gt Latent (Evaporation) - about
75 gt The Bowen Ratio (BR) is the ratio of the
sensible heating to latent heating Bow
en Ratio Sensible Heating Latent
Heating Thus, the Earths average BR 25 /
75 0.33
37
Earths Surface Energy Budget
Energy Absorbed at the Earths Surface
(Cont) Convection (Cont) - Two types
(Cont) gt The Bowen Ratio (BR) varies depending
on the surface type and meteorological
conditions Geographical Area Bowen
Ratio Europe 0.62 Asia 1.14 No
rth America 0.74 South America 0.56
Africa 1.61 Australia 2.18 Atlantic
Ocean 0.11 Indian Ocean 0.09 Pacific
Ocean 0.10 All land 0.96 All
oceans 0.11
Note Dry areas like Australia have high BR while
wet areas like oceans have low BRs, i.e., over
dry areas, more energy is transferred from the
surface to the atmosphere via sensible heating
while over wet areas, more energy is transferred
to the atmosphere via evaporation of water
38
Earths Surface Energy Budget
Energy Absorbed at the Earths Surface
(Cont) Convection (Cont) - Two types
(Cont) gt Examples 1. Congo rain forest
maximum surface temperatures about 30C
cooler than adjacent semiarid lands 2.
Dense irrigated poplar tree farm (red) next to
arid natural vegetation in northeastern Oregon
http//www.agu.org/journals/eo/eo0643/ 2006EO43000
2.pdf
Eos, Vol. 87, No. 43, 24 October 2006
39
Earths Surface Energy Budget
Energy Absorbed at the Earths Surface
(Cont) Convection (Cont) - Two types
(Cont) gt BR varies depending on soil
moisture availability gt Advanced
Spaceborne Thermal Emission and Reflection
Radiometer (ASTER) images on 8/27/06
Top vegetation index, a measure of
plant density Dense vegetation is dark
green Sparse vegetation is pale
green Bottom is surface
temperature Note contrast between irrigated
and non-irrigated land, irrigated crop
lands are much cooler, 30C (54F) cooler,
than surrounding native vegetation
http//earthobservatory.nasa.gov/Newsroom/ NewImag
es/images.php3?img_id17486
40
Earths Surface Energy Budget
Energy Absorbed at the Earths Surface
(Cont) Convection (Cont) gt The Bowen
Ratio (BR) Effect of soil moisture
on maximum temperatures Eta model
volumetric soil water content (0-10
cm) over Northern Alabama and daily
maximum temperature at Huntsville, AL
41
Earths Surface Energy Budget
Energy Absorbed at the Earths Surface
(Cont) Radiation - Infrared (IR) or
Longwave wavelengths - Accounts for about 80
of energy transfer
42
Earths Radiation Energy Budget
Science Concepts Reflection and
Scattering Atmospheric Gases Clouds Absorption
Atmospheric Gases Clouds Transmission Atmospheri
c Gases Clouds
Longwave Radiations Interaction with
Atmosphere Greenhouse Gases Longwave Radiation
Budget
43
Earth or Longwave Radiation
What happens to longwave radiation emitted by
Earths surface? Absorbed, transmitted or
reflected by the atmosphere - 5
transmitted - 95 absorbed Absorbed by
Greenhouse gases - Water Vapor
Absorption ()
44
Earth or Longwave Radiation
Interaction with Earths Atmosphere (Cont)
Absorption ()
Absorption ()
45
Earth or Longwave Radiation
Interaction with Earths Atmosphere
(Cont) Absorbed by Greenhouse gases
(Summary) - Atmospheric Window gt 8-11
microns
46
Earth or Longwave Radiation
Interaction with Earths Atmosphere
(Cont) Clear atmosphere absorbs Earths
radiation Interaction with Clouds Liquid
water (cloud droplets) absorbs almost all IR
(Infrared or longwave radiation) Emit IR in
all directions depending on its temperature
47
Clouds and Radiation Budget
Effects of Clouds Reflect solar
radiation Absorb longwave radiation Net
Effects of Clouds Deep, convective clouds
- Have tops that are highly reflective (high
albedo) to solar shortwave radiation - cooling
effect gt However, because their tops are high,
and thus cold, they emit little longwave from
their tops - Bases readily absorb Earths
longwave radiation - warming effect - Net
result is that deep, convective clouds have a
neutral (neither warming or cooling) effect on
Earths climate system
48
Clouds and Radiation Budget
Net Effects of Clouds (Cont) Clouds
(Cont) - High, thin cirrus clouds gt Mostly
transparent (low albedo) to solar
radiation gt Readily absorb Earths
longwave radiation and emit longwave
in all directions, some up and some
down gt Net result is they warm Earths
climate system - Low, thicker altostratus or
stratus clouds gt Highly reflective (high
albedo) to solar shortwave radiation gt Readi
ly absorb Earths longwave radiation and emit
longwave in all directions, some up and some
down gt Net result is that they cool the Earths
climate system
49
Clouds and Radiation Budget
http//earthobservatory.nasa.gov/Newsroom/ NewImag
es/images.php3?img_id17474
Net Effects of Clouds (Cont) Condensation
trails (Contrails) - If air through which
the airplane is flying is nearly saturated,
contrail will form easier and last longer
than if the air is dry - Lingering contrails
can spread out into a cirrus layer of
cirrus - This MODIS image on 11/25/06
contains scores of contrails over the
Midwest, - Mingled contrails have created a
thick cloud over the top part of the scene
(not all the clouds in the region are necessarily
contrails) - To the south, more distinct
individual tracks are visible
50
Clouds and Radiation Budget
http//earthobservatory.nasa.gov/Newsroom/ NewImag
es/images.php3?img_id17474
Net Effects of Clouds (Cont) Condensation
trails (Contrails) - Contrails can
influence the climate by increasing the
cloud cover in heavy air-traffic
regions - Recall thin cirrus clouds cause
warming their thinness makes them not
very good solar radiation absorbers, but
they do absorb outgoing radiation - NASA
scientists have discovered that
contrail-generated cirrus clouds could be
responsible for much of the warming of surface
temperatures over the U.S. from 1975-1994
51
Clouds and Radiation Budget
Net Effects of Clouds (Cont) Reducing Night
Flights May Ease Winter Global Warming, Report
Says Clouds of ice formed in the trails of jet
exhaust trap heat and prevent the earth from
cooling. From the Los Angeles Times By Robert Lee
Hotz, June 15, 2006 Contrails from winter night
flights may be most responsible for the global
warming caused by air traffic, even though they
constitute a fraction of commercial flights,
meteorologists at the University of Reading
reported Wednesday. Though there would be
enormous practical problems, airlines could
markedly reduce aviation's impact on climate by
changing schedules to restrict night flying, the
researchers said in the journal Nature. "We get
one-half of the climate effect from one-quarter
of the year, from less than one-quarter of the
air traffic," said meteorologist Nicola Stuber,
who led the English research team. "If you get
rid of the night flights, you can reduce the
climate warming effect of the contrails."
Overall, aviation accounts for a relatively
small portion of the emissions involved in rising
global temperatures, but international commercial
air travel is among the fastest growing
unregulated sources of greenhouse gases and a
topic of concern among climate regulators.
http//www.latimes.com/news/printedition/asection/
la-sci-nightfly15jun15,1,3604880.story?collla-ne
ws-a_section
52
Clouds and Radiation Budget
Net Effects of Clouds (Cont) Reducing Night
Flights May Ease Winter Global Warming, Report
Says (Cont) By its accounting, the
International Air Transport Assn. says that air
traffic accounts for just 2 of global carbon
dioxide emissions. Jet exhaust, however, injected
at high altitude can have two or three times the
warming effect of carbon dioxide alone,
researchers have concluded. In particular,
climate experts have worried about the impact of
the trails of ice particles that quickly condense
in the wake of jet exhaust, which can spread in
hours from a few yards wide to thousands of
square miles. These shining clouds are mirrors in
the sky. From their upper surface, they reflect
solar radiation, causing a slight cooling. At the
same time, they block any heat rising from the
earth below, enhancing the greenhouse effect. At
night, that warming is especially pronounced, the
researchers determined. To explore the climate
effects of contrails, Stuber and her colleagues
studied the airspace over the south of England at
the entrance to the North Atlantic flight
corridor, perhaps the world's busiest skyway,
with as many as 36,000 flights per month.They
looked only at information on contrails that
persisted for an hour or more, combining aircraft
flight data with weather balloon recordings of
temperature and humidity. Contrails were almost
twice as likely to form in winter as in summer.
http//www.latimes.com/news/printedition/asection/
la-sci-nightfly15jun15,1,3604880.story?collla-ne
ws-a_section
53
Clouds and Radiation Budget
Net Effects of Clouds (Cont) Reducing Night
Flights May Ease Winter Global Warming, Report
Says (Cont) Stuber determined that night
flights accounted for 25 of the daily air
traffic but contributed 60 to 80 of the climate
effect. Moreover, winter flights accounted for
22 of the annual total but contributed half of
the annual warming. "If we control emissions
from other sources and don't do something about
aircraft, then in the future they are going to
become a dominant source," said atmosphere expert
Joyce E. Penner at the University of Michigan.
"Maybe there are ways to avoid such a high
climate impact by scheduling different routings."
http//www.latimes.com/news/printedition/asection/
la-sci-nightfly15jun15,1,3604880.story?collla-ne
ws-a_section
54
Clouds and Radiation Budget
Net Effects of Clouds (Cont) Clouds
(Cont) - Clouds containing many aerosols
(left) also contain many tiny water droplets
- Such clouds reflect light (solar
radiation) well - Clouds containing fewer
aerosols (right) tend to contain fewer and
larger water droplets - they transmit more
solar energy to the Earths surface
http//science.nasa.gov/headlines/y2002/ 22apr_cer
es.htm?list104690
55
Earth Energy Budget
Budgets Percentage W / m2
http//www.globalchange.umich.edu/globalchange1/ c
urrent/lectures/samson/global_warming_potential/
http//asd-www.larc.nasa.gov/ceres/ brochure/cloud
s_and_energy.html
56
Earth Energy Budget
Budgets Percentage
http//asd-www.larc.nasa.gov/erbe/components2.gif
57
Earth Energy Budget
http//www.ngdc.noaa.gov/paleo/ctl/about4.html
Budgets Percentage W / m2
Note numbers do not exactly match, but this
depiction shows the greenhouse effect
58
Earth Energy Budget
Budgets Surface (Watts m-2)
Atmos. Solar Earth Sensible Latent
Solar Top of Atmos. Source Rad. Rad. Heat
Heat Absorb Albedo National Acad. of
Sciences (1975) 174 72 24
79 65 30 Paltridge Platt (1976) 174 68 27 7
9 65 30 Budyko (1982) 157 52 17 88 81 30 Ma
cCracken (1985) 157 51 24
82 79 31 Henderson-Sellers 171 68 24 79 6
8 30 Robinson (1986) Ramanathan
(1987) 169 63 16 90 68 31 Schneiderf 154 55
17 82 86 30 Liou (1992) 151 51 21 79 89 3
0 Peixoto Oort (1992) 171 68 21 82 68 30 Ha
rtmann (1994) 171 72 17 82 68 30 Rossow
Zhang (1995) 165 46 66 33 Kiehl
Trenberth (1997) 168 66 24 78 67 31 Top of
Atmosphere Incoming Solar radiation 342 Watts
m-2 Kiehl, J.T., and K.E. Trenberth, 1997
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