Exam 3 Lecture Slide Content Flashcards
OZONE
Where does the ozone layer exist and what is its primary function?
The ozone layer primarily exists in the stratosphere and is used to block harmful incoming UV waves.
Where is ozone good and where is ozone harmful?
Ozone is good in the stratosphere but is harmful in the troposphere
What are the three chemical reactions that take place for ozone to be created?
Ozone exists in the stratosphere as a process of three fast chemical reactions driven by UV light:
-O2+hv (UV light)= 2O
-O+O2= O3
-O3+hv= O2+O
What are CFCs (Chloroflurocarbons)?
CFCs are halogen compounds designed to be inert in the troposphere- they are compounds that act as ideal refrigerants and propellants
What is the Halogen Depletion Hypothesis?
Halogen Depletion Hypothesis: Hypothesis that CFCs can make their way into the stratosphere where the process of photo disassociation frees the CL from the original CFC molecule; the CL then reacts with the O3 to reduce the overall amount in the atmosphere
What is photodissociation?
Chemical reaction in which molecules of a chemical compound are broken down by photons (a quantum of light or electromagnetic radiation)
How was the Halogen Depletion Hypothesis tested and verified?
A spy plane was used to scan evidence to test for three hypothesis-found that “Elevated levels of reactive chlorine in the ozone depleted zone – allowed them to reject the null hypothesis of no relationship between the two.”
What were the other two plausible hypothesis for ozone reduction in the stratosphere? Explain them
Find this lol
What are the two key roles of the southern Polar Vortex
-Traps gases like CFCs
-Forms polar stratospheric clouds where the breakdown of CFCs is accelerated
What are the three steps to the formation of the polar vortex
-cold winter air forms a vortex
-early spring brings more solar radiation which then causes photodissasociation freeing more Cls from CFCs
-In late spring, warmth returns, breaking up the polar vortex. Throughout the summer, ozone levels increase again as polar air mixes with the surroundings
What are the two reasons why ozone depletion is less of an issue in the North Pole?
-Land mass is unevenly distributed (weaker vortex, trapping less air)
-Comparatively warmer temperatures (limits the formation of polar winds forming the vortex and formation of stratospheric clouds)
What was the target set in the Montreal Protocol?
the Montreal Protocol set a target for 50% reduction in CFCs by 1997 (this number was not determined by anything) which jogged the industry into looking into alternatives.
What alternatives were used instead of CFCs and why?
HFCs and HCFCs were used instead which emulated similar cooling effects to CFCs but could be broken down in the troposphere.
POLLUTION
What is the difference between primary and secondary pollutants?
-Primary pollutants: Enter the atmosphere in a form that is harmful to life or things (ex.) carbon monoxide)
-Secondary pollutants: Formed in the atmosphere by the interaction between primary pollutants and sunlight and other gases (ex.) ozone)
What are the five important pollutants as discussed by Kaufman and Cleveland?
-Carbon monoxide (CO)
-Hydrocarbons (VOX)
-Particulates/Aerosols
-Nitrous Oxides (NOX)
-Ozone
What is carbon monoxide?
A product of imcomplete combustion of hydrocarbons
Produced in reactions where:
-oxygen is insufficient
-temperature is too low
-air supply rate is too fast
-mixing in combustion chamber is insufficient
What is the primary source of CO emissions? Secondary source?
-Mobile engines (on and off road) are responsible for 80% of emissions
-Stationary sources are responsible for only 6%
How does carbon monoxide harm species?
Carbon monoxide binds to hemoglobin, an iron based compound that binds to oxygen, transporting oxygen to the bloodstream.
What are particulates?
Solid or condensed liquids that are suspended or floating in the atmosphere
What are aerosols?
Mixture of liquid and solid particulates- this term can be used interchangeably with particulates
What is the primary source of particulate pollution? Secondary?
-40% come from industry
-20% from road vehicles
What are the three variations of particle size for particulates?
-PM(10): between 10 and 2.5 microns (also called coarse particles)
-PM(2.5): below 2.5 (also called fine particles)
-PM(0.1): below 0.1 (ultra fine particles)
Important to note that the smaller the particle size, the more dangerous the particle is
How do the different particle sizes differ from eachother?
Particle size determines how long a particle can stay in the atmosphere- larger than PM(10) settle more quickly, fine and coarse particles can travel longer distances, and ultra fine particles can resist gravity settling but may be more likely to stick to larger particles or be deposited onto the surface
Particle size also determines how particles affect human health- larger than PM10 can be blocked by nose hairs and mucus, fine particles may be inhaled deeply, and ultra fine particles can influence body chemistry
How do aerosols impact rainfall?
Aerosols cause the “weekend effect” on rainfall- water droplets condense on particles (nucleation). This causes more rainfall to occur during the end of the week as pollutants from the work week form clouds by the weekend.
What is Sulfur Dioxide?
SO2 is a compound that can act as either a primary or secondary pollutant.
-As a primary pollutant, SO2 has effects on human respiration and plant growth.
-As a secondary pollutant, SO2 can form droplets along with the acid H2SO4 causing acid rain precipitation.
What are Nitrogen Oxides (NOX)?
a catch-all for all reactive nitrogen compounds; NOX are generated during fossil fuel combustion
What are the chemical reactions that cause NOX?
-As a first step NO is produced (odorless and colorless gas)
-NO oxidizes to NO(2) (also mostly harmless)
-However, when confronted with hv, NO2 dissociates into nitric oxide and oxygen
-O radical reacts with oxygen to form ground-level ozone
Why is ground-level ozone harmful?
Ground level ozone is harmful as a secondary pollutant. It is a component of photochemical smog which has consequential effects on human health, plant growth, etc.
Where are NOX emissions most common?
NOX emissions are most common in cities but can remain in kilometers outside of them
What are hydrocarbons? More specifically, what are VOCS?
hydrocarbons are a compound of hydrogen and carbon. VOCs are a subsect of hydrocarbons called volatile organic compounds (VOCs)
Where do VOCs come from?
VOCs arise from combustion or industrial processes but are also common to find in nature? VOCs are important in plant-plant and plant-animal communication.
What role do VOCs play as primary pollutants?
VOCs as primary pollutants are harmful towards indoor air quality.
What role do VOCs as secondary components?
When combined with NOX, VOCs act as a component of photochemical smog, contributing to a greater production of ozone.
What three factors shape the concentration of emissions?
-Emissions
-Volume of air that they are emitted into
-Reaction and deposition removal processes
What is the vertical mixing height/layer?
Altitude or “ceiling” to which pollutants are able to rise
What is the horizontal movement?
Distances that pollutants are carried from their source by the wind
What is advection and convection? What is the difference between these two movement patterns?
-Advection pertains to horizontal movements of pollutants driven by pressure gradients (wind movements).
-Convection pertains to vertical movements through the turbulent, vertical exchange of air. Convection is limited by stability of the troposphere
-it is important to consider that advection doesn’t necessarily alter the concentration of pollutants rather simply carrying them to a new location.
In regards to atmospheric stability, what is the lapse rate?
The temperature change as you go up in latitude.
In regards to atmospheric stability, what is the adiabatic lapse rate?
In contrast to the actual lapse rate, the adiabatic lapse rate is the “ideal” lapse rate. Comparing this to the actual lapse rate can help assess how stable or unstable an atmosphere is.
Using the actual and adiabatic lapse rate, how do we categorize unstable, neutrally stable, and stable atmospheres?
-Unstable atmospheres are atmospheres when the upper air is cooler than the adiabatic lapse rate. The adiabatic air parcel is warmer than the environment surrounding it causing it to rise.
-Neutrally stable atmospheres are atmospheres where the adiabatic air parcel is the same temperature as the environment surrounding it causing it to stay in place.
-Stable atmospheres are atmospheres when the upper air is warmer than the adiabatic lapse rate. In this, the adiabatic air parcel is cooler and denser causing it to sink.
What is a radiation inversion?
Radiation inversion is when the temperature rises with altitude rather than becomes cooler. In this case, adiabatic parcels definitely will not rise at all.
When does radiation inversion normally occur? What are some of the consequences if it does not occur at this time?
Radiation inversion usually occurs at night. However, sometimes it occurs during the day which traps pollution underneath.
What are subsidence inversions?
Subsidence inversions occur as a large air mass sinks causing it to heat up relative to the air underneath.
Where are subsidence inversions most common?
Subsidence inversions are most common in cities near 30 degrees latitudes.
Unstable, neutrally stable, and stable atmospheres all correlate with different types of mixing depths. What is fanning and which atmosphere does it correlate with?
-Fanning is when stable atmospheres cause exhaust to move downwind without much vertical motion only spreading out horizontally.
Unstable, neutrally stable, and stable atmospheres all correlate with different types of mixing depths. What is fumigation and which atmosphere does it correlate with?
-Fumigation is caused by downward mixing and is common in stable atmospheres and atmosphere with inversions.
Unstable, neutrally stable, and stable atmospheres all correlate with different types of mixing depths. What is looping and which atmosphere does it correlate with?
-Looping is the process of upward mixing and is common in unstable atmospheres.
What policy framework has decreased the atmospheric concentration of air pollutants?
NAAQs
What are the two sets of air quality standards and what are the difference between them?
-Primary standards protect public health including sensitive populations such as children or the elderly.
-Secondary standards protect public welfare including damage to crops, animals, vegetation, or property
What are non attainment areas?
Areas where these standards are not viable
How did NAAQs internalize externalities to decrease atmospheric pollution?
NAAQs established nationwide standards which forced firms to pay the cost of compliance rather than individual citizens. NAAQs were enforced nationally therefore disincentivizes corporations to relocate inter or internationally as the cost of compliance was lower than the cost of relocating.
However, it is important to note that this is a concern for other pollutants where weaker environmental standards internationally would appeal to polluters