Ozone A PLANETARY CONTEXT Presented by Stephen Schneider Deborah Carlisle.

OzoneOzoneA PLANETARY CONTEXTA PLANETARY CONTEXT

Presented by Presented by

Stephen Stephen SchneiderSchneider

Deborah CarlisleDeborah Carlisle

Interpolating Color Data

User Comments Average Red

Average Green

Average Blue

exercising 70.3 65.1 5.1resting 47.2 58.1 15.80% CO2 22.5 47.9 39.81% CO2 35.6 55.2 23.410% CO2 74.7 62.9 0.850% CO2 81.7 68.1 0.8

0% 1% 10% 50%

You can interpolate graphically ormathematically. Having calibrated samples close to the right color willimprove your accuracy.

0% CO2 resting exercising

1% CO2 10% CO2 50% CO2

Rest % = 1% + × (10% – 1%) = 1% + 0.299 × 9% = 3.7% 47.2 – 35.674.7 – 35.6

Atmospheric Absorption

• The Earth’s atmosphere absorbs most wavelengths of the radiation incident on it from space

• This is a good thing for life – high energy photons would sterilize the planet!

• It’s an intriguing coincidence(?) that our eyes work at wavelengths where the atmosphere is transparent.

Why Space-based Observatories?

Atmospheric HeatingStratosphere• Oxygen (O2) is split apart

by solar ultraviolet light, and O atoms recombine to make ozone (O3).

• O2 and O3 both absorb ultraviolet light, heating this layer.

Troposphere• Sunlight heats surface.• Atmosphere absorbs heat

from surface.

6Ozone (parts per million)

0

20

40

60

80

100

Alt

itud

e (k

m)

Troposphere

Mesosphere

Thermosphere

Ozone In the AtmosphereA

ltitude (miles)

10

0

20

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60

90% of ozone is in the stratosphere

0 2 4 6 8

10% of ozone is in the troposphere

7

UVc - 100% AbsorptionUVb - 90% Absorption

UVa - 50% Absorption & Scattering

Ozone is the Earth’s natural sunscreen

Ozone (parts per million)

0

20

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Alt

itud

e (k

m)

Troposphere

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Thermosphere

Altitude (m

iles)

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0 2 4 6 8

Earth’s Energy Budget

9

October Average Ozone HoleOctober Average Ozone Hole

LowOzone

HighOzone

10

16%

32%

23%

12%

7%5%

1%4%

0

3400

3000

2000

1000

(CH3CCl3)

(e.g., HCFC-22 = CHClF2)

(CCl2FCClF2)

Naturalsources

Other gasesMethyl chloroform

HCFCs

CFC-113

Carbon tetrachloride (CCl4)

CFC-11 (CCl3F)

CFC-12 (CCl2F2)

Methyl chloride (CH3Cl)

0

20

15

10

5

15%

27-42%

5-20%20%

14%

4%

Methyl bromide (CH3Br)

Halon-1211 (CBrCIF 2)

Halon-1301 (CBrF3)

Other halons

Very-short lived gases (e.g., bromoform = CHBr3)

Chemicals that Destroy Stratospheric Ozone

• Cl is much more abundant than Br• Br is about 50 times more effective at O3 destruction

From Ozone FAQ - see http://www.unep.org/ozone/faq.shtml

Ground-level Ozone• Ozone problems are

caused by pollutants, not greenhouse gases.

• At ground level, the presence of NOx and volatile organics stimulates production of this caustic chemical.

• Ozone can cause lung damage and exacerbate breathing problems.