I. Physical Principles: The foundation & the tools Newton's laws: forces, pressure, motion

Energy: Temperature, radiant energy

II. Atmospheric & Ocean Physics: First element of climate and environmental science

Atmospheric structure (T, P in "4-D") Winds, Weather, General Circulation, Climate

III. Atmospheric & Ocean Biogeochemistry: Second element of climate and environmental science

Atmospheric and ocean composition, past and present Human impact, global change

IV. Intersection: what we know, would like to know, will never know, and what can we contribute to the debate.

L-2 L-3

Solid bodies emit thermal radiation at rates that depend on temperature. Hot bodies (sun) emit more radiation at shorter wavelengths than cold bodies (earth).

Emission rate=!T4

Road map to EPS 5 Lectures 3 and 4: Atmosphere Heat, Energy, Radiation

Black Bodies, Planck Function,

Stefan Boltzmann Law

Planets radiate on average at the Effective Temperature, to maintain energy balance with sun and space, Absorption of ir in the atmosphere traps energy, radiating back to the surface and causing it to warm up.

Teff = [Fs(1 - A)/(4!)]!

= 252.6 K

Tg = [n + 1]1/4Teff.

Effective T, greenhouse effect Feedback!

Atmospheric Radiation: The Earth receives energy from the sun (on average 344 W/m2) and emits the same amount to space The energy balance of planet earth

The temperature of the earth’s surface has been remarkably constant over geologic time. Even the dramatic cooling during the ice age represented a change of only 3° C in the global average surface temperature, occurring over thousands of years. Seasonal changes in temperature, although large in a particular place, correspond to very tiny changes in global mean temperature.

How is this remarkably steady condition maintained?

To maintain the long-term stability of earth’s temperature, the planet must radiate to space a flux of energy sufficient to just balance the input from the sun, i.e. the earth is, to good approximation, in radiative energy balance.

1. Atoms form chemical bonds by rearranging electrons in the outer (valence) shell to localize the electrons between the nuclei.

2. Light may be regarded as both a propagating electric field in the shape of a sine wave and as particles called photons. The relationship between the speed of light (c), its wavelength ("), and its frequency (#), is c = "#.

3. Every photon has a specific energy proportional to its frequency, or inversely proportional to its wavelength, E = hc/" = h#.

4.! Most atmospheric gases can neither emit nor absorb light at the long wavelengths (infrared) emitted by cold objects, such as the Earth. Those relatively rare atmospheric molecules that can absorb infrared radiation have asymmetric distribution of charge (e.g. a dipole, like the water molecule) that causes the molecules to experience a force due to the oscillating electric field of the light.

5.! Matter can emit light only at wavelengths that it can absorb.

6. Matter emits radiation depending on its temperature. The total flux of radiation emitted is given by the Stefan-Boltzmann equation, Flux (W m-2) = !T4, where ! is the Stefan-Boltzmann constant, 5.67x10-8 W m-2 K-4. The flux as a function of wavelength is given by the Planck function, FLUX (") =

[2$ hc2 / "5 ]/[exp( hc/(" kT) ) – 1 ], (W m-2 m-1).

A brief introduction to light and matter

6

Protons, neutrons, electrons, and electrostatic forces. •!Atoms are the fundamental chemical building blocks of matter, the smallest unit that retains chemical identity. An atom is made up of protons (positive charge), neutrons (zero charge), and electrons (negative charge). The protons and neutrons are packed together in the nucleus and the electrons forming a cloud of negative charge around the nucleus.

•!The size of an atom (diameter of the electron cloud) is ~10-10 m, but the

nucleus is smaller by factor 100. The atomic unit of length is the Ångström, 1 Å % 10-10 m, named to honor Anders Ångström (1814-1874), Swedish physicist who improved the precision in measuring the wavelength of spectral lines.

•!Electrostatic forces are responsible for holding atoms together or forcing them apart. When electric charges, q1 and q2 are distance r apart, the electrostatic

force between them is F = q1q2/r2, and the energy of interaction is E = q1q2/r

(the energy it takes to bring them to distance r from infinity). If the charges are of like sign (both + or both -), the force is repulsive, the energy is positive, and the charges will tend to fly apart. Charges with opposite signs are attracted and the electrostatic force pulls the charges together. q is the charge, it comes in multiples of the electron charge.

+ -

+

-

E

electric field

torque on the dipole

(molecule)

"electroscope"

apparatus for

determining the

charge on an

electron

F = q1q2 / r2

Density of electron charge (net negative charge, shown in red and green) relative to the positions of the nuclei and inner-shell electrons (net positive charge, dark blue) in the molecule Si3. The maxima of electron density between the nuclei provide clouds of negative charge that attract the positively-charge nuclei and hold the molecule together. (Figure by Dr. Masao

Arai, National Institute for Research in Inorganic Materials, Japan.)

Electrostatic forces hold the atoms

in a molecule together (or can push them apart…).

Molecules that have opposite electric charges at either end (“dipole moment”) can absorb or emit electromagnetic radiation (light) in ways that affect the heat balance of the earth. The major molecules of air (O2, N2) do not have dipole moments, and they cannot emit or absorb light in this way.

To understand why dipole moments are important in absorption and emission of light, we need to study the properties of light.

Light and radiant heat (infrared radiation) propagate through space

as waves, called electromagnetic waves because there are an

electric field and a magnetic field associated with each wave (the magnetic field is not important for our purposes).

The O atom in water partially pulls the electrons away from the H atoms, giving its side of the molecule a small negative charge (-2&) and the H side a small positive charge (+& on each H-atom).

If we could take a snapshot of a light wave as it traveled for 1 s, it would be 3'108 m long, and would look like the sine wave shown in the figure. The distance between two successive crests on the wave is called the wavelength (denoted "). The frequency (denoted #) is the number of wave cycles (wavelengths) that pass a reference point per unit time, and since our snapshot shows exactly the number of peaks that passed in one second, # is also the number of peaks in the picture, i.e. # =c/". Alternatively, 1/# is the time it takes the wave to travel one wavelength at

speed c. " # = c

Electromagnetic radiation, although wave-like in nature, is composed of packets of energy called photons. Thus light is both a wave and a particle. For a given electromagnetic wave of wavelength " the energy associated with each photon is given by

E = hc/" = h#

where h is Planck's constant (h=6.626x10-34 J sec). This was one of Planck's great discoveries; it implies that photons with shorter wavelengths are

more energetic than photons with longer wavelengths and light comes in

defined packets with a particular amount of energy in each one (given by h#).

Light and matter in fact are always dual waves and particles.

Photoelectric effect

Observation: when certain metals are exposed to light, and electric current can be made to flow in a circuit. Only wavelengths shorter than a threshold make this happen. The energy in each electron is

proportional to 1/", and the number of electrons depends on the

intensity of the light. This is how a solar cell works… 14

Photovoltaic cell layout http://science.nasa.gov/science-news/science-at-nasa/2002/solarcells/

Matter emits radiation if its temperature is above 0 K (absolute zero). An object

that absorbs radiation at all wavelengths incident on it necessarily emits

radiation at all wavelengths. This ideal material is called a black body; solid objects, such as the the earth, or liquid water, behave almost as black bodies. Planck showed that the intensity of light that is emitted from a black body as a function of wavelength (") or frequency (#), is given by the following function (now called the Planck function):

[2$ hc2 / "5 ] FLUX (") =

[exp( hc/(" kT) ) – 1 ],

(units: Watts m-2 m-1; 1 W % 1 J s-1) is the amount of energy in light with " between " and "+(" passing through surface with area 1 m2 each second.

Planck’s Law indicates that the temperature of an object determines the intensity

of radiation emitted by the object at any wavelength, provided that the object can absorb radiation at that wavelength.

"max = b/T (Wien's displacement law: peak of Planck function)

<= Planck function

The Planck function for several temperatures is plotted versus wavelength " (upper scale, 1 µm = 10-6 m) or wave number (% 1/" = #/c; wave numbers are proportional to photon energy, like #, but in units more convenient than frequency).

Planetary Radiation Solar Radiation

Pla

nck F

un

cti

on

(W

m-2

/ cm

-1)

Pla

nck F

un

cti

on

(W

m-2

/ cm

-1)

wavenumber (cm-1) wavenumber (cm-1)

wavelength (µm) wavelength (µm)

The Planck function gives the energy flux from an object divided up according to wavelength (or frequency), for a given temperature. Long before Planck, however, scientists had determined by direct experiment that the total energy flux from an object, at all wavelengths, depended only on temperature, and they derived an empirical equation called the Stefan-Boltzmann law to describe this relationship:

TOTAL ENERGY FLUX = ! T4 .

Here the total energy flux (units: W m-2) is shown to vary as the 4th power of the absolute temperature, T (K), with a constant of proportionality ! = 5.67 ' 10-8 W m-2 K-4, the Stefan-Boltzmann constant. The Stefan-Boltzmann law was obtained in the 19th century by observing the rate at which real objects lost energy via radiation, with many decades passing before Planck showed that it could be derived from his radiation law.

Electromagnetic spectrum: Atmospheric Radiation

106

20

visible

"color temperature"

The oven demonstration:

We took two objects of different materials (e.g. a brick and a steel ball) that look different in reflected light, and placed them in an oven that can reach about 900 C (1200 Kelvin). At this temperature they emit light at a high rate at wavelengths that we can see visually.

Even though they looked different in reflected visible light, both objects look the same as they glow under these conditions. In fact it will often be difficult to see them at all inside the oven, which is also glowing. This experiment illustrates that ordinary solid objects emit and absorb radiation more or less like "black" bodies, which is the same as saying that their emission spectra follow Planck's equation.

Lantern slide projector demo:

Put a strong prism in front of a lantern slide projector to disperse the light, and varied the temperature of the lamp by changing the applied voltage (for example, using a variable transformer). The rapid disappearance of the blue light will be apparent as the temperature is lowered (and vice versa), as will changes in the total amount of light coming from the projector. This experiment visualizes Planck’s function directly and illustrates the phenomena that Planck sought to explain. The changes in emission rate at various wavelengths relate directly to our understanding of sunlight and of heat radiation from the earth.

23

The IR camera demonstration:

We deployed an infrared camera that creates images using longwave infrared radiation. We observed how matter at different temperatures radiates longwave radiation, and we were able to create simple analogs of the "greenhouse effect" using materials like mylar, lexan, etc.

The earth’s albedo (fraction of solar radiation *reflected* to space) was first measured by observing earthshine on the moon, reflected back to earth and visible just after the new moon. It is now measured from spacecraft. About 33% of the solar energy incident on the earth is reflected back to space, A=0.33.

Most of the reflection of solar radiation from earth is due to

clouds, with help from sea ice and glacial ice in Antarctica and Greenland, plus snow and deserts (albedo 0.6—0.9).

The albedo of the earth’s surface is mostly much lower than 0.33, about .07 for land with vegetation, 0.05-0.1 for the ocean.).

Thus the albedo, and the entire energy budget of earth, is

sensitive to cloudiness and ice cover, factors that change on

both weather and climate time scales (short and long times).

Albedo

Earth's albedo for March, 2005 (CERES satellite)

ALBEDO

The term has its origins from a Latin word albus, meaning “white”. It is

quantified as the fraction of incident solar radiation of all wavelengths reflected by a body or surface.

O r=1.5 x 1011 m

o

sun earth

Diagram of the sun and earth, and an imaginary sphere with radius 1.5x1011m with the sun at the center.

The surface area of this sphere is 4$r2.

We can compute, using the Stefan-Boltzmann Law, the total amount of energy (L) radiated by the sun each second,

L = !Ts4 '4$Rs

2 = 3.9 x 1026 watts, where 4$Rs

2 is the surface area of the sun (Rs=6.6 ' 108m), !Ts4

is the Stefan-Boltzmann law giving the energy flux per unit area, and Ts is the temperature of the sun’s surface, 5800 K.

The same total amount of energy L must also cross the sphere of radius r each second.

The solar flux (Watts m-2) at the earth, Fs, is defined as the energy crossing a square meter of the sphere at earth's orbit each second. It is given by

Fs = L/(4$r2) = !Ts4 '(Rs

2/r2) = 3.9x1026/( 4$(1.5x1011)2 ) =

1379 W m-2

The solar flux Fs (also called the solar constant) is the radiant energy from the

sun that falls per second a 1 m2 surface oriented perpendicular to the sun’s rays,

at the top of the earth's atmosphere.

1379 / 4 ! 344

The total solar energy striking by the earth per second can be calculated by multiplying Fs by the shadow area (not the total surface area!) of the earth , i.e. the area of solar beam intersected the earth.

The amount of energy striking the earth is given by the [shadow area (black circle) ' the solar flux] =$Re

2 Fs. (Re is the radius of the earth).

The total energy flux striking the surface of the earth is therefore Fs $Re2.

SUN

Not all solar radiation intercepted by the earth is absorbed. The fraction of incident solar radiation reflected is defined as the albedo, A, and the fraction absorbed is therefore (1-A).

The total energy input to earth (Joules per second) is thus

Eabs = Fs$Re2(1 - A). INPUT

Energy INPUT to the earth from the sun

Energy OUTPUT from earth by thermal radiation

The total energy emitted per unit area is given by !T4, and the emitting area is the surface area of the earth, 4$Re

2.

The total energy emitted by the planet per second is therefore

Eemit = 4$Re2 !T4 . OUTPUT

Energy balance requires that input=output, when averaged over a long-

enough period of time, i.e. on average Eemit = Eabs. Thus

4$Re2!T4 = Fs$Re

2(1 - A) .

(This is the Energy Balance Equation). This equation can be solved for

the average temperature at which the earth must emit radiation to bring

the energy budget into balance, called the effective temperature Teff of

the planet:

Teff = [Fs(1 - A)/(4!)]! = 252.6 K.

!"#$"%&'%(")%'&**&+#,-%.(/()0),(.%$&,$)1,#,-%(")%2-31)%4)*&+%/1)%(13)5%

67%8")%9)/:%&'%(")%.&*/1%1/;#/<=)%>3?%#.%+#("#,%(")%=#.#4*)%1/,-)%&'%(")%

)*)$(1&0/-,)<$%.9)$(130%

@7%8")%1/;#/<=)%>3?%/(%(")%.31'/$)%&'%(")%A3,%#.%-1)/()1%("/,%(")%1/;#/<=)%>3?%

/(%(")%.31'/$)%&'%(")%B/1("%!"#!$$#%!&'$'()"*+#

C7%8")%(&(/*%),)1-D%>3?%'1&0%(")%B/1("%#.%03$"%*)..%("/,%(")%(&(/*%),)1-D%>3?%

'1&0%(")%A3,%

E7%6%/,;%C%&,*D%

B7%6**%&'%(")%/4&=)%

planet solar flux orbit radius albedo Te Tg Ground pressure

(W m-2) (1011 m) (K) (K) (bar)

Mercury 9200 0.6 0.058 442 442 ~0

Venus 2600 1.1 0.77 227 750 90

Earth 1400 1.5 0.33 253 288 1

Mars 600 2.3 0.15 216 240 0.007

Jupiter 49 7.8 0.58 98 (no surface) (no surface)

Effective Temperatures of the Planets

After Goody and Walker, "Atmospheres"

2001

Earth's Albedo can change with time, affecting the

energy budget and temperature of the planet.

Top o

f Atm

osp

here

Flu

x A

nom

aly

W m

-2

Atmospheric absorption of infrared radiation

•!The most abundant gases in the atmosphere, N2, O2, and Ar, neither absorb nor emit terrestrial radiation. (They also neither absorb nor emit most wavelengths of solar radiation, except for ultraviolet light).

•!The relatively rare molecules that can absorb long-wave (terrestrial) infrared radiation are called greenhouse

gases. They can trap infrared radiation emitted by the Earth much as the glass in a greenhouse traps heat.

•!The most important greenhouse gases in the atmosphere are H2O and CO2, and gases such as methane (CH4) and chlorofluorocarbons are also significant.

Greenhouse gases: Water, CO2, CH4

Water interacts with electromagnetic waves with both a permanent dipole moment (left) and dynamic ("transition") dipole moment due to the changes in the +& and –& as the molecule vibrates.

O = C = O

O O C

+2&)

-&)-&)

CO2 with electromagnetic waves with only dynamic ("transition") dipole moment due to the changes in the +& and –& as the molecule vibrates (bending or "asymmetric stretch").

molecules radiate frequencies they can absorb: Kirchhoff's Law

•!Due to the presence of gases that can absorb infrared radiation, the atmosphere acts as a blanket, allowing solar energy to reach the surface but preventing the heat from escaping directly back to space.

•!The atmosphere is warmed by the absorbed terrestrial radiation.

•!Molecules that can absorb radiation of a particular wavelength can also emit that radiation according to Kirchhoff's radiation law. The Greenhouse gases in the atmosphere will therefore radiate, both to space and back towards the earth's surface. This back-

radiation warms the earth's surface.

The Greenhouse Effect: influence of atmospheric absorption

and emission of planetary (infrared) radiation

reflected solar

(A)

incoming solar radiation (Fs)

(visible, near infrared)

!)Tg 4

terrestrial (far infrared) radiation from the surface

!)T e 4

!)T e 4

far infrared radiation

from the atmosphere

z=H

The atmosphere and the ground radiate energy according to the Stefan-Boltzmann law. Examine the energy balance of the layer at H (intended to be a scale height, or ~ 7km, on earth) in this hypothetical planet. The total amount of energy radiated per square meter per second is 2!T1

4, (OUT) because the layer radiates equally both up and down. But the amount received by the layer is !Tg

4, (IN) (heated only from below!). If the layer has a balanced energy budget, these two fluxes must be equal (IN = OUT),

!Tg4 = 2!T1

4 . { T1 =>> Teff}

Thus the ground is warmer than the atmosphere by Tg = 21/4Teff. This happens because the atmosphere is warmed only by absorbing radiation from the earth's surface, i.e. from one side (below), but it radiates both up and down.

The atmosphere must have a lower temperature than the ground in order to satisfy its energy balance. This result for 1 layer in the atmosphere can be

generalized to any number (n) of layers,

!Tg4 = [n + 1] !T1

4

Tg = [n + 1]1/4Teff .

The atmosphere therefore gets colder as we go up due to the effects of absorption and emission of radiation (terrestrial infrared radiation).

SOLAR RADIATION SPECTRUM: blackbody at 5800 K

TERRESTRIAL RADIATION SPECTRUM FROM SPACE: composite of blackbody radiation spectra for different T

Scene over!

Niger valley,!N Africa!

cf. clouds, aerosols

Climate forcing due to human—caused changes in concentrations of

greenhouse gases, atmospheric aerosols, and clouds, since 1850 (Hansen, 2001).

ATMOSPHERIC CO2 INCREASE OVER PAST 1000 YEARS

I. Physical Principles: The foundation & the tools Newton's laws: forces, pressure, motion

Energy: Temperature, radiant energy

II. Atmospheric & Ocean Physics: First element of climate and environmental science

Atmospheric structure (T, P in "4-D") Winds, Weather, General Circulation, Climate

III. Atmospheric & Ocean Biogeochemistry: Second element of climate and environmental science

Atmospheric and ocean composition, past and present Human impact, global change

IV. Intersection: what we know, would like to know, will never know, and what can we contribute to the debate.

L-2 L-3

aerosols

albedo

"Feedback"

FEEDBACKS

Consider how these factors may change, what may cause these changes, and how the various changes may interact with each other. This brings us to the concept of feedback:

property A increases !

property B changes !

causes property A to increase further

property A increases !

property B changes !

causes property A to decrease

Positive feedback makes the climate system more sensitive to a change in property A; negative feedback makes it less sensitive. The concept of feedback

depends on a formulation of direct vs. secondary effects, based on separation in

time or some other criterion.

+ positive feedback (amplification)

+ negative feedback (damping)

ice-albedo feedback – solar radiation

Temperature increases " polar ice recedes " Albedo decreases

" Temperature increases

This is a very strong feedback when there is a lot of polar ice, for example, at the height of the last ice age. It works both ways, helping the ice sheets to advance as the earth cooled, by amplifying the cooling, and accelerating the retreat of the ice sheets as the climate started to warm. There is rather little polar ice in glaciers today, so feedback on land ice is not likely to play a major role in climate change. But sea ice coverage is

significant, and uptake of heat by the underlying ocean could have effects on both temperature and rainfall. Sea ice will be discussed in detail later.

+

FEEDBACKS INVOLVING ALBEDO (continued)

+

+

FEEDBACKS INVOLVING ABSORPTION OF IR (HEAT)

Examine some of the most important feedbacks in the Earth’s atmosphere.

water vapor feedback.

Temperature increases " atmosphere H2O increases (Clapeyron equation)

" atmospheric absorption increases (n) " Temperature increases

This is the strongest feedback mechanism in the atmosphere. It is also the best understood since it is based simply on the measured increase in water vapor pressure increase with temperature (Clapeyron equation).

cloud feedback – terrestrial radiation

Temperature increases " atmosphere H2O increases (Clapeyron equation)

" cloudiness increases (n) " Temperature increases

This is a very strong feedback that is not well understood because it is hard to know whether or how much cloudiness would increase as temperature does—cloudiness depends on upward air motion more than on T or H2O directly.

cloud feedback – solar radiation

Temperature increases " atmosphere H2O increases (Clapeyron equation)

" cloudiness increases (n) " Albedo increases

" Temperature decreases

This is also very strong feedback that is not well understood because it is hard to know whether or how much cloudiness would increase as temperature does, and because of the trade-off (competition) between the effects of clouds on absorption of infrared radiation versus reflection of solar radiation. Low-altitude clouds affect albedo more than they affect ir radiation, and conversely for high clouds (discussed below).

vegetation feedback – solar radiation

Temperature increases " deserts expand " Albedo increases

" Temperature decreases

This is a very complex feedback that will take a long time to be realized. Maybe deserts won't expand, or plants will be greener because there is more CO2 ?

-

FEEDBACKS INVOLVING ALBEDO

-

Longwave radiation as viewed from

the satellite sensor "ERBS" on NOAA-9, April, 1985

Low OLR in the tropics is due to: 1. Obscuring the surface by clouds; 2. Cold T at cloud tops 3. Smoke from fires 4. Both 1 and 2 are correct.

No Data 100 150 200 250 300 350

Watts m-2

Climate forcing due to human—caused changes in concentrations of

greenhouse gases, atmospheric aerosols, and clouds, since 1850 (Hansen, 2001).

Water vapor is not listed. Why not ? 1.! Water vapor does not emit infrared radiation 2.! It is assumed that humans have not changed concentrations of water vapor. 3.! A mistake—it should be listed. 4.! Effects of water vapor are already included in cloud effects.

FUTURE TEMPERATURE PROJECTIONS FROM CLIMATE MODELS (IPCC, 2001)

Solid bodies emit thermal radiation at rates that depend on temperature. Hot bodies (sun) emit more radiation at shorter wavelengths than cold bodies (earth).

Emission rate=!T4

Road map to EPS 5 Lectures 3 and 4: Atmosphere Heat, Energy, Radiation

Black Bodies, Planck Function,

Stefan Boltzmann Law

Planets radiate on average at the Effective Temperature, to maintain energy balance with sun and space, Absorption of ir in the atmosphere traps energy, radiating back to the surface and causing it to warm up.

Teff = [Fs(1 - A)/(4!)]!

= 252.6 K

Tg = [n + 1]1/4Teff.

Effective T, greenhouse effect Feedback!

Atmospheric aerosols: Global cooling?

Aerosols are suspended particles in the air which are small enough to resist gravitational sedimentation (i.e. they remain afloat despite the force of gravity acting on them). Aerosols can be solid, liquid, or a combination of both. They typically range in size from 0.1 to 1.0 micrometers. The main sources of aerosols are dust from the surface, sea spray (liquid droplets and solid sea-salt particles), volcanoes, forest fires, and anthropogenic combustion.

Direct effect: aerosols scatter sunlight, increasing albedo, cooling the atmosphere.

Black carbon effect: if aerosols have black carbon (soot…) inside, they can be heated by sunlight, warming the atmosphere.

Indirect effect: aerosols affect the formation of cloud droplets. Increased aerosols may lead to smaller droplets, more cloudiness, and higher albedo, cooling the earth by lowering Teff.

Aerosol Optical Depth after the eruption of Mt. Pinatubo

(SAGE-II Satellite data)

Mt. Pinatubo eruption

1991 1992 1993 1994

-0.6

-0

.4 -0

.2 0

+

0.2

Tem

pera

ture

Change (

oC

)

Global Temperature

Climate Model

Effect of a major volcanic eruption on climate ( after Hansen et al., 1993).

Note: many feedbacks have not come into play.

Volcanic eruptions can inject millions of tonnes of dust and gaseous sulfur dioxide into the stratosphere. The finer dust particles remain aloft for years and spread around the world while the sulphur dioxide evolves to an aerosol of sulfur acids that add to the particulates. The dust and aerosol produce vivid sunset and twilight effects like the intense yellow-red horizon and purple-pink glows of the photograph. The purple glow is probably a combination of red-orange light transmitted through the lower atmosphere and scattered blue light from still sunlit stratospheric dust.

http://www.atoptics.co.uk/atoptics/sunvolc.htm

AEROSOL OBSERVATIONS FROM SPACE

Biomass fire haze in central America (4/30/03)!

Fire locations!

in red!

Modis.gsfc.nasa.gov!

BLACK CARBON EMISSIONS DIESEL!

DOMESTIC!

COAL BURNING!

BIOMASS!

BURNING!

“…Kyoto also failed to address two major pollutants that have an impact on

warming:!!black soot and tropospheric ozone.!!Both are proven health hazards.!!Reducing both would not only address climate change, but also

dramatically improve people's health.” (George W. Bush, June 11 2001 Rose Garden speech)!

EPA REGIONAL HAZE RULE: FEDERAL CLASS I AREAS TO RETURN TO “NATURAL” VISIBILITY LEVELS BY 2064

Acadia National Park!

clean day! moderately polluted day!

http://www.hazecam.net/!Latitude 80 N; Date: 2009 11 02

Photo: E. Kort