1. Boundary-Layer Meteorology and Atmospheric Dispersion
Dr. J. D. Carlson
Oklahoma State University
Stillwater, Oklahoma

2. Mechanisms of Heat Transfer in the Atmosphere-Earth System
Radiation (no conducting medium)
Sensible Heat Transfer (large-scale movement of heated material)
Latent Heat Transfer (change of phase associated with water)
Conduction (molecule to molecule)

3. in the Earth-Atmosphere System
RADIATION
in the Earth-Atmosphere System

4. Shortwave Radiation
Longwave Radiation
SUN
EARTH

5. Longwave
Shortwave

6. THE
GREENHOUSE
EFFECT

7. MERCURY VENUS Sunlit Side = 800 F Dark Side = -279 F
NO Greenhouse Effect
VENUS
Surface Temp = 900 F
Large Greenhouse Effect

10. RADIATION AT THE EARTH’S SURFACESW SW LW LW
Shortwave (solar) radiation reaches a portion of the earth’s surface (SW )
A portion of that solar is reflected back (SW )
Albedo (α) = the fraction of solar radiation reflected (SW = α SW )
Albedo values: Dark soil
Dry sand
Meadow
Forest
Water
Fresh snow
Old snow
The surface receives longwave (infrared) radiation from the sky (LW )
The surface emits longwave radiation to the sky (LW )
The sum of the four radiation terms is often called “Net Radiation” (R)

11. (How is the net radiation partitioned at the earth’s surface ?)
SURFACE ENERGY BUDGET
(How is the net radiation partitioned
at the earth’s surface ?)

12. SURFACE ENERGY BUDGET DAY NIGHT SW = shortwave radiation received
SW = shortwave radiation reflected
LW = longwave radiation received
LW = longwave radiation emitted
H = sensible heat transfer by turbulence, advection, convection
LE = latent heat transfer (change of phase: evaporation, condensation,
freezing, thawing)
G = heat transfer through the submedium (conduction)
SW + SW + LW + LW + H + LE + G = rate of warming or cooling of surface
DAY LE G
Energy Units = (surface warming) +9 -7
NIGHT LE G
Energy Units = (surface cooling) -7 +5

14. ATMOSPHERIC BOUNDARY LAYER Daily Behavior under High Pressure Regimes

15. = LAPSE RATE ∂T T2 – T1 ∂z z2 – z1 Typical Vertical Profiles of
Wind and Temperature during
the Course of a 24-h Fall Day with Clear Skies
(note formation and growth of
temperature inversion during the night)
“Inversion” = temperature
increases with height =

17. T2, z2
LAPSE RATE
∂T T2 – T1
∂z z2 – z1
T1, z1 =

18. Surface Radiation Inversion

19. Temperature Profile
Radiation Inversion

20. Subsidence Inversion
HIGH PRESSURE

21. Temperature Profile
Subsidence Inversion

23. ATMOSPHERIC DISPERSION
1. General mean air motion that transports the pollutant
a. horizontally - “advection”
b. vertically - “convection”
2. Turbulence - random velocity fluctuations that disperse the pollutant in all directions
3. Molecular diffusion - due to concentration gradients

24. Mechanical (wind-related) 2. Thermal (temperature-related)
TURBULENCE
Mechanical (wind-related)
2. Thermal (temperature-related)

25. MECHANICAL TURBULENCE
Speed shear
Directional shear
Surface frictional effects

26. THERMAL TURBULENCE

27. DENSITY DEPENDS ON TEMPERATURE
Ideal Gas Law:
PV = nRT
(P = pressure, V = volume, n = # moles,
R = Universal gas constant, T = Absolute Temp)
Can be rewritten: P = rRT, where r = Density
For two air parcels at the same pressure, the warmer
parcel has the lower density:
r = P / RT

29. without any heat exchange)
ADIABATIC LAPSE RATE
(rate of temperature change that an air parcel experiences as it changes elevation
without any heat exchange)
(dT/dz)adiab = Γ = - g/cp = -1C/100 m = -5.4F/1000 ft z T

30. ENVIRONMENTAL LAPSE RATE
(actual rate of temperature change with height
of the current atmosphere)
(∂T/∂z)env = environmental lapse rate z T

31. (∂T/∂z)env < Γ
(∂T/∂z)env = Γ
(∂T/∂z)env > Γ

32. THERMAL STABILITY (∂T/∂z)env < Γ Unstable (∂T/∂z)env = Γ Neutral
(∂T/∂z)env > Γ Stable

33. TYPES OF ATMOSPHERIC DISPERSION
Weather
Factors
Side View
(vertical dispersion)
Top View
(horizontal dispersion)
UNSTABLE
ATMOSPHERE
NEUTRAL
STABLE
TYPES OF ATMOSPHERIC DISPERSION

34. PLUME BEHAVIOR

35. Unstable Atmosphere – Good Dispersion

36. LOOPING Larger scale convective turbulence dominates
Γ (adiabatic)
environmental
Larger scale convective turbulence dominates
Strong solar heating with generally light winds
Super-adiabatic lapse rates

41. Neutral Atmosphere – Moderate Dispersion

42. CONING Γ Near neutral conditions (adiabatic lapse rates)
Overcast days or nights
Moderate to strong winds
Small-scale mechanical turbulence dominates

46. Stable Atmosphere – Poor Dispersion

47. FANNING Γ Strong inversion (large positive lapse rate) at plume height
Extremely stable conditions (buoyancy suppression)
Typical of clear nights with light winds

52. Special Cases

53. LOFTING Γ Inversion layer below plume
Pollutants dispersed downwind with minimal surface
concentration
Sometimes a transition to a fanning plume

57. FUMIGATION Γ Opposite of lofting
Inversion lies above plume with unstable air below
Typical of early morning as inversion breaks up from below
Short duration, high surface concentrations

59. TRAPPING Γ
Subsidence inversion aloft (well above plume) with unstable air below
Typical of weather conditions featuring high pressure

61. Six types of plume behavior, under various conditions of
stability and instability. At left: broken lines: dry adiabatic
lapse rate; full lines: existing environmental lapse rates.

62. PLUME RISE

66. Minimal plume rise due to strong winds

67. DIFFERENT PLUME HEIGHTS

70. Example of Complex Shear Flows along a Coastline
Salem, Mass.
Oil-fired power plant looking south on a winter morning.
Lower steam plume from two 250-ft stacks trapped by inversion.
Upper plume from a 500-ft stack.
East
Atlantic Ocean
Shoreline
Inland
West

71. Types of Air Pollutants
Gases
Particulate Matter
PM10 (< 10 microns dia.)
PM2.5 (< 2.5 micron dia.)

72. Types of Emission Sources

81. GAUSSIAN PLUME MODELING

85. Emissions from Pollutant Sources
Emission Rate (amount/time)
Height of release
Plume rise (thermal effects)
Plume descent (gravitational effects)

86. σz σy
Diagram showing Gaussian distribution of pollutant plume. σy and σz are
standard deviations of the horizontal and vertical concentration distributions,
respectively.

87. Physical system
Model system
Bounded space; plume
Unbounded space; no reflection

89. Class A results in the most dispersion, while Class F has the least.
Category A represents very unstable conditions; B, moderately unstable; C, slightly unstable; D, neutral; E, slightly stable; and F, stable. Night refers to the period from one hour before sunset to one hour after sunrise. The neutral category, D, should be used regardless of wind speed for overcast conditions, day or night.
Thermal turbulence dominates
(buoyancy enhancement)
Mechanical turbulence only
Thermal effects dominate
(buoyancy suppression)
Classes E-F
Class A results in the most dispersion, while Class F has the least.