1. Transport of Air Pollutants
Marti Blad, Ph.D., P.E.
Yavapai Apache Nation

2. What is the Difference?
The difference is meteorology!

3. What we will learn Pollutants move and spread in air
Up and down (vertical)
Away and outward (horizontal)
Dispersion vs Diffusion
Slowly “spread” out in all directions (diffusion)
Simply use this to give everyone an idea of what they should get out of this module.

4. Diffusion & dispersion

5. Transport of Air Pollutants
Weather conditions are important
Temperature
Affect Molecule dance
Pressure
Affects density
Volume Temperature and Pressure related

6. 3 parts to puzzle Source of pollutant How transported
Stationary vs Mobile
Control technologies
Physical, Chemical, Biological
How transported
Fate of pollutant
Toxicology & Chemistry
Receptor or recipient
Philosophy of pollution prevention. Only 3 basic ways for things to be controlled – let me know if you can think of anymore. Physical , chemical and biological forces or laws. Most of what we use in AP is physical laws rule, some chemical, very little biological at this time. Use biology for wastewater.
Same laws in the universe – we will look briefly at some equations but don’t panic!
Real concern is will someone be exposed/hurt? Populations at risk – children and elderly. Separate topic not covered here

7. Pollutants moving through air
2 ways to look at mathematically
Box: Mass Balance
Flux = mass / (time x area)
Follow one particle
X, y, z, and time
Mass Transport
Pollutant has mass so can be tracked
Models use mass
Use this to put “air pollution transport” into plain English. Lagrangian and Eulerian mathematics = which are used in different models. Basic differences in the mathematics based on the way you look at the pollutant/particle. Draw on board

8. Momentum transfer Air pollutants can move horizontally As fast as wind
wind speed
Flow = advection,
In direction of wind (wind direction)
Wind Rose
activity later w James
Pressure currents in atmosphere
Diffusion different than Dispersion
Continue putting concepts into plain English.

9. Heat transfer Air pollutants can move vertically
Convection
Cities as “Heat Island”
Air temperature changes with altitude
Ambient air temperature decreases as you go up
Colder on mountain than in Phoenix
Pressure changes with altitude
Pressure decreases as you go up
Less Molecules on top of you at 7000 ft
1 atm = sea level
Think away from core heat is why temperature goes up
Pressure is the wieght of the atmosphere above it – therefore at 7000 feet there is less atmosphere pressing down. Important to understand soundings as they use pressure as an axis

10. Changes in meteorology and climatology
Molecules have mass and are transported
Heat transfer
Temperature difference
Momentum
Wind speed
Wind direction
Pressure systems
Think away from core heat is why temperature goes up
Pressure is the wieght of the atmosphere above it – therefore at 7000 feet there is less atmosphere pressing down. Important to understand soundings as they use pressure as an axis

11. Atmospheric stability
When air overhead is cold compared to air near ground, vertical motion stronger. (Unstable)
When air overhead is closer to ground temperature prevents air from moving vertically. (Stable)
When air is warmer overhead than near ground, “inversion” (molecule dance lid)
Continue putting into plain English.
Try to act out each example with the molecule dance. Think of the temperature difference and which molecules have more energy. This slide describes our demonstration later

12. How does stability affect what I can see?
Smoke plume behavior – a useful indicator
Predict Good burning days
Models use “stability class”
How can pollutants concentrate?
Under an inversion
Maximum mixing height
Mixing height:
Height plume will rise to given prevailing atmospheric conditions
Talk through upcoming pictures of various plume examples and link to the stability condition. NEXT SLIDES
Explain how a high pressure system can create an inversion aloft and then use the overhead of mixing height to tie together the ideas of air rising per DALR and reaching same temp point where it stops. This defines how much volume we have for pollutants to mix or concentrate within.

13. Predict Stability by slope
temperature change  altitude change
Can be positive or negative slope
Ambient Lapse Rate
Recorded by weather stations
Dry Adiabatic Lapse Rate (DALR)?
Theoretical line with constant slope
Slopes are rates (per time)
How dry air rises and falls
Cools 1° C for each 100 meters rise
Warms 1° C for each 100 meters fall
Use overheads with this.
Use overhead of a simplified temp profile with positive lapse; draw on it to show + lapse
Use overhead of a simplified temp profile with negative lapse; draw on it to show – lapse
Use either prior overhead to run through several different calculation of ALR
Use the 3 overheads of DALR vs. ALR and “air parcels” to explain the connection between DALR-ALR, vertical movement of air parcel & the concept of stability conditions (unstable, neutral, stable, inverted lapse or inversion).

14. DALR Dry adiabatic lapse rate Speed pollution disperses & diffuses
Air expands as pressure decreases
Function of elevation
Rate at which dry air cools at it rises
Adiabatic = no heat exchange
Approx. 1° C for every 100 meters
Speed pollution disperses & diffuses
Based on “Air stability”
Relationship between ambient & DALR
Compare slopes
Confusing subject so I am going to be very redundant
Draw on board
Relate elevation to temperature
Will see pictures

15. Mixing Height: Adiabatic compared to ambient
DALR is dotted line labeled “r”. See where it meets the ambient temperature profile line (dark solid). Realize Pressure is same as height because of the weight of atmosphere.

16. Atmospheric stability
See Pictures comparing Slopes
Neutral= DALR slope
Superadiabatic
Unstable air favors dispersion
Molecules moving
Subadiabatic
Stable air so poor dispersion
Inversion
Warm air over cold air
Generally describes behavior – remember we learned about slopes already. See the big picture with slopes.

17. Slopes of different conditions
Inversion
superadiabatic
subadiabatic
Dry adiabatic lapse rate = neutral
DALR
What the previous slide was talking about. Compare to DALR which is theory

18. Stability affects plume shape
Series of pictures to help you understand new vocabulary
Why? To predict or to understand the meteorology at that height and temperature. Use with method 9 (smoke school)
Important to start seeing the release height of stack in relationship to the temperature profile
smoke stacks image from Univ. of Waterloo Environmental Sciences

19. Dotted line is DALR – compare the slopes of dotted line to straight line – remember previous slides. Point out height of stack and where line is. Assumption of wind direction and speed

20. Dotted line is DALR. Need to see release height as key point in the DALR and ambient LR

21. Dotted line is DALR. Location of stack release in comparison to slope
Dotted line is DALR. Location of stack release in comparison to slope. Notice no plume rise.

22. Stability affects plume shape
Superadiabatic
looping plume
Adiabatic
coning plume
Inversion
Fanning plume
Inversion over superadiabatic
fumigation
New vocabulary – same as previous slide

23. Atmospheric Stability Classes
How is stability classified?
Stability classifications
A = strongly unstable B = moderately unstable
C = slightly unstable D = neutral
E = slightly stable F = moderately stable
How does stability relate to air pollution?
UNSTABLE
Good vertical mixing & dispersion of pollutants
STABLE or INVERSION
Poor vertical mixing & dispersion of pollutants
See following table -again the terms that are used in reports etc. I remember that unstable means lots of mixing. Stable is every molecule at same energy as neighbor molecule so not much mixing
Will be used in modeling section – stability class critical to curve shape in modeling

24. Will use this with modeling exercise
Will use this with modeling exercise. Useful to understand and plan Burn days

25. Vertical Dispersion & Diffusion
Worst pollution episodes often correspond to inversion trapping pollution near ground during calm periods
Shallow inversions common at night & in winter (can be especially strong in geographical basins where cold air pools)
Deeper inversions can be caused by large-scale subsidence of air. As air moves toward ground, compressed and heated. Can lead to a capping inversion layer 3000 to 6000 feet off ground
Differentiate between Fairbanks type inversions and LA type.
Special models for coastal conditions, conditions of uneven terrain, building downwash etc.
Use diesel engine example to back up compressional heating idea.

26. What do you think is happening here?
Note that plume from stack is rising – due to heat out of stack, Need stack velocity and this distance of rise, delta H.
Notice: lower level sources are being trapped below shallow inversion
What do you think is happening here?

27. Another Example
Space Shuttle image of smoke trapped by morning valley inversions in the Pacific Northwest, see spatial relationship with terrain, water, and source. See narrow plume and then spreads out on other side of ridge – looks drier side.

28. Upper Air Data Soundings Radiosondes Isotherms Isobars Isohumes
Dropsoundes
Rocketsondes
Isotherms
Isobars
Isohumes
This can be confusing because they way we draw in class or think of it is not the way meteorologist & climatologist present the data. Atmosphere is so complex that we use 3 and 4 axis graphing- excel coming up to help with complex graphing to convey information.
Might see this terminology: NOAA etc to get data from website – important in modeling, backward trajectory etc

29. OK so here is what they will show – same axes of isotherms, isobars, and isohumes but we have added the DALR = Dry Adiabatic Lapse Rate and one more! Moist ALR (Adiabatic Lapse Rate). Don’t you love it!
5 things on one graph! Realize moist air- reality acts different from dry air –theory and both are shown on this graph.

30. What We Just Covered Pollutants move and spread in air
Diffusion and Dispersion
Vertically and horizontally
Transport phenomena
Weather conditions dictate transport
Actual temperature profile=ambient
DALR = theoretical comparison
Speed pollution disperses & diffuses
Based on Air stability class
Source height & mixing height
Simply a recap moving us toward modeling air pollution transport.

31. Laboratory: Create an Inversion
Hands-on exercise in stability
(see manual)