Chapter 3 – Meteorology (Air-Pollution Meteorology)

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A set of Q&A flashcards summarizing definitions, processes, and relationships essential to Chapter 3 on Air-Pollution Meteorology.

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33 Terms

1
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What does Air-Pollution Meteorology study?

The atmospheric processes and phenomena that influence weather and the concentration of pollutants.

2
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Name the four primary meteorological factors affecting pollutant concentration.

Wind speed and direction, temperature, atmospheric stability, and mixing height.

3
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List four secondary meteorological parameters that influence air quality.

Rainfall/precipitation, humidity, solar radiation, and visibility.

4
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How does high wind speed affect pollutant concentration near the emission source?

It carries pollutants away and dilutes them rapidly with surrounding air.

5
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What is gustiness and why is it important?

Rapid fluctuations in wind speed; it enhances mixing and dilution of pollutants.

6
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Which instrument measures wind speed?

An anemometer.

7
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Define atmospheric stability.

The tendency of the atmosphere to encourage or suppress vertical air motion.

8
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What is the normal environmental lapse rate given in the notes?

A temperature decrease of 6.4 °C per 1000 m (or 1000 ft).

9
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What is a temperature inversion?

A reversal of the normal lapse rate where cold dense air is trapped below warmer air, preventing vertical mixing.

10
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During an inversion, where are pollutants concentrated?

Below the inversion layer near ground level.

11
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Why are inversions considered ‘stable’ atmospheric conditions?

Because vertical air movement (and thus mixing) is suppressed.

12
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Describe a radiation inversion.

Night-time cooling creates a cool ground layer capped by warmer air, common in winter and valleys.

13
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What causes a subsidence inversion?

Slowly sinking air in an anticyclone that warms adiabatically aloft and traps cooler air below.

14
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What is mixing height?

The height above ground to which pollutants can be vertically mixed by turbulence.

15
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State two meteorological factors that largely determine mixing height.

Wind direction and wind speed (also turbulence).

16
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Explain rainfall’s ‘two-fold cleansing’ action on air pollutants.

Rain accelerates deposition of particulates and washes soluble gases from the atmosphere.

17
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How does humidity affect air-pollution impacts?

High moisture can enhance corrosive reactions and promote fog formation with pollutants.

18
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Why is solar radiation important to air quality?

It drives photochemical reactions among pollutants and provides surface heating that influences stability.

19
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Define dry adiabatic lapse rate (DALR).

Temperature drop of unsaturated air: ~9.8 °C per km (5.4 °F per 1000 ft).

20
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Define wet adiabatic lapse rate (WALR).

Cooling rate of saturated air (~6 °C per km) due to latent heat release during condensation.

21
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What is a plume in air-pollution terminology?

The visible or invisible stream of emitted gases moving from a source into the atmosphere.

22
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Define plume rise.

The vertical distance a hot plume travels above the stack due to buoyancy and momentum.

23
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Give three factors that influence plume behaviour.

Stack height, diurnal variation, and seasonal variation (also stability, wind speed, etc.).

24
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How does increasing stack height generally affect ground-level pollution?

It promotes better dilution aloft and reduces ground-level concentrations.

25
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Write the formula for effective stack height (H).

H = h (physical stack height) + Δh (plume rise).

26
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Which plume pattern is characterized by strong instability and a wavy path?

Looping plume.

27
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Under what condition does a neutral plume occur?

When the environmental lapse rate equals the adiabatic lapse rate, allowing vertical rise until density equalizes.

28
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Describe a fanning plume.

A horizontal plume with little vertical mixing, occurring under strong inversion conditions.

29
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Which plume pattern is considered best for air quality and why?

Lofting plume, because strong upward diffusion prevents pollutants from reaching the ground.

30
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Which plume pattern is worst for ground-level pollution and why?

Fumigating plume; pollutants are forced downward by an inversion layer above the stack.

31
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What is a wind rose used for?

Graphically displaying the frequency and speed of winds from different directions at a location.

32
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List four key inputs to plume dispersion theory.

Plume temperature, emission rate, stack height/diameter, and wind speed/direction (plus stability, topography).

33
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Name two NEERI-developed instruments for meteorological measurement.

Wind Direction Recorder and Wind Speed Recorder (also temperature and solar-radiation measurement devices).