AqL1 and 2 March12

ES 200Second Half Semester

18+ Lectures

Professor Anurag GargProfessor Subhankar Karmakar

Professor Virendra SethiCESE

In Service of YOU

Professor Arcievala:

“Three things I learnt at Harvard:1. Quantification

2. Library work and

3. Apprenticeship”

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Air QualityLecture 2

Virendra Sethi

vsethi@iitb.ac.in

7809

Let’s Get Started

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ES 200 Environmental Studies

Air Quality

Pre-course Quiz

not for grade

Phew !!!

Thank God for small mercies !!!

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What is Air Pollution ?

• Perception– Visible– Odour

• What is clean air ?– 78% Nitrogen + 21% Oxygen + 1% Trace– 340 ppm CO2 (0.034%) (YEAR ???)

• Water – Heat Released/Absorbed

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Lifecycles/Statistics

• Capacity of the earth system as a sink– Feasibility (thermodynamics)– Proximity

• Characteristic times– Kinetics– Sulphur, Carbon, Nitrogen, Halogen Containing

Compounds Cycles

• Statistics

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Scales

• Local > Regional > Global

• Earth : Apple :: Atmosphere : Skin

• Ambient : Indoor

• Dispersion and Mixing

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Class Exercise

• Given : Regulatory Limit for SO2 in Ambient Air is – 80g/m3 (0.03 ppm) for annual average– 1300 g/m3 (0.5 ppm) for 3 hour average

• How many grams of Sulphur, if burnt in this lecture Hall, would pose a health risk to you ?

• S + O2 = SO2

• 32 gm S gives 64 gm of SO2

• X gm will give 2X gm

• Mixed in how much volume ? Will lead to exposure concentration…

Actual Question then is …

• What is the volume of air in this Hall

(in m3 ) ?

Prizes to be Won

DOUBLE DHAMAKA

Closest to Actual – 5 Star Chocolate

Closest to Average – 5 Star Chocolate

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Caution

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Results from Previous Year

1

10

100

1000

10000

100000

1000000

10000000

100000000

0 20 40 60 80 100 120 140 160 180

Students

Estim

ated

Vol

ume

of F

CK

ohli

Aud

itoriu

m (m

3)

Series1

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Results

• RANGE – 20 mg of Sulphur (panic buttons for no

reason)– 8 kg of Sulphur (dead people with Karma to

blame)

• Low Sulphur diesel YET ?

• Ships affecting coastal cities ?

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Air QualityLecture 2

Virendra Sethi

vsethi@iitb.ac.in

7809

19

How do we manage Air Quality ?

• At the source itself– Industry– Vehicles– Dust– Home cooking

• After the source– Dispersion and Mixing

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Mixing/Dispersion

• Meteorology– Vertical

• Temperature– Lapse Rate

– Horizontal• Wind

– Speed – Direction

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Dispersion – Gaussian Plume

WIND

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Wind Rose

http://www.epa.gov/ttn/naaqs/ozone/areas/wind.htm#dlfi

1 knot = 1.82 km/hr

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• Wind roses are divided into 16 wind directions

• Each wind direction is divided into wind speeds

• As the percent of time the wind blows from a particular directions gets larger, the portion of the bar representing the wind speed gets larger both in length and width

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Mixing/Dispersion

• Meteorology– Vertical

• Temperature– Lapse Rate

– Horizontal• Wind

– Speed – Direction

30http://www.ldeo.columbia.edu/edu/dees/ees/climate/slides/atmprofile.gif

COMING SOON

Earth ki Kahani – Naam toh

Sunaa hoga !

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Lapse Rates

• Atmosphere cools with height– What rate ?

• Dry (Adiabatic) 10°C/km• Wet (Adiabatic) 6°C/km

– (Release of heat with condensation)

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ACTUAL

ADIABATIC (1°C/100 m)

1000 m (say)

20 °C19 °C18 °C

20 °C Air Parcel

19 °C Air Parcel at 1100 m

1100 m

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ADIABATIC (1°C/100 m)

1000 m (say)

20 °C 21°C 22 °C

20 °C Air Parcel

21 °C Air Parcel at 1100 m

1100 m

900 m

ACTUAL

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ADIABATIC (1°C/100 m)

1000 m (say)

20 °C19.5 °C19°C

20 °C Air Parcel

19 °C Air Parcel at 1100 m

1100 m

ACTUAL

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WIND

Adiabatic

Actual

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ScenariosAdiabatic

ActualH

eig

ht

Temperature

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ScenariosAdiabatic

ActualH

eig

ht

Temperature

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ScenariosAdiabatic

ActualH

eig

ht

Temperature

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Stability

http://www.tpub.com/content/aerographer/14312/css/14312_47.htm

Wet Lapse Rate

Dry Lapse Rate

Average

Unstable

Stable

Height

Temperature

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Match the Profile

Unstable

Stable

Plumes (a) (b) (c) (d)

(Adapted from Masters, 1997)

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Match the Profile

Unstable

Stable

Plumes (a) (b) (c) (d)

(Adapted from Masters, 1997)

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Review

Dispersion and Mixing Influenced by :• Wind

– Speed– Direction– Wind Rose

• Temperature Lapse Rates– Dry adiabatic– Wet Adiabatic– Stability

Contextual Communication

• Where to stand when participating in this course : – Good Citizen OR Decision Maker– How would this apply to my home city ?

• Grading :– 20 Questions : 20 Answers

Home Work

Please study the film

“An Inconvenient Truth”

(Al Gore)

before the March 21st Class

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