midterm Flashcards
- What are the three main atmospheric elements?
o Nitrogen (78%)
o Oxygen (20.9%)
o Argon (0.93%)
- Do nitrogen levels vary a lot in the environment?
o No, nitrogen levels remain consistent in the environment
- What is happening to the concentration of nitrogen in the atmosphere because of human activity?
o Nitrogen concentrations are increasing
- What is the role of nitrogen in the environment?
o Limited direct role but serves as a precursor molecule of nitrate which is used by plants to synthesize molecules essential to life
- Why is having too much nitrogen in the atmosphere bad?
o Too much nitrogen results in algal blooms which suffocates the water
- Why is oxygen important?
o Vital to almost all life
o Precursor for O3 which absorbs high energy UV light
- What is argon?
o An inert gas
- What are the trace gases that make up the rest of the atmosphere composition?
o Carbon dioxide
o Water vapor
- What is the source of carbon from which all life is based?
o Carbon dioxide in the atmosphere
- What chemical compound is the basis for the Global Warming Potential (GWP)?
o Carbon dioxide
- What is the Global Warming Potential (GWP)?
o The potential of any chemical to add to the global warming problem
- What does it mean if methane has a GWP of 28?
o 1 molecule of methane contributes as much as 28 molecules of carbon dioxide
- What compound is the most important greenhouse gas?
o Carbon dioxide
- Why is carbon dioxide the most important greenhouse gas?
o Carbon dioxide accounts for the greatest portion of warming by anthropogenic activities
- T/F. Carbon dioxide levels are steady in the environment?
o False, carbon dioxide levels are increasing
- When did carbon dioxide levels begin to rise?
o 1870, the industrial revolution
- Why do we have a huge increase in carbon dioxide levels beginning in 1960?
o The development of cars becoming cheaper
- What is the most variable atmospheric component?
o Water
- What is vapor pressure?
o The partial pressure of water vapor
o Humidity
- What are the two types of humidity?
o Absolute
o Relative
- As temperature increases, what happens to the ability of air to hold water?
o Air can hold more water at higher temps
What happens to relative humidity as the temperature increases
o Relative humidity decreases as temperatures increase
o Since air can hold more water at higher temperatures
- What are the components of the Psychrometric chart pictured on the right?
o Dry bulb
o Wet bulb
o Specific humidity
o Dew point
o Relative humidity
o Saturation line
o Humidity ratio
- How do you get the dry bulb temperature?
o Hang a thermometer
- Where is the wet bulb temperature on the psychrometric chart?
o The top curved line
- How do you get the wet bulb temperature?
o They take a thermometer and cover it with a wet cloth and as the water evaporates it cools off
- What is the wet bulb temperature in comparison to the dry bulb temperature?
o Wet bulb temperature is always less than the dry bulb temperature
- Where is the specific humidity on the psychrometric chart?
o Right side
o Shows the humidity ratio in pounds of water per pounds of air
- What is grains of water?
o Specific humidity
o How many grains of water you have in the pound of air
- What is dew point?
o 100% humidity
- Where is the dew point depicted on the psychrometric chart?
o Same line as wet bulb
- Where is relative humidity depicted on the psychrometric chart?
o The curved line
- At 100% relative humidity, what is the the relative humidity similar to?
o The wet bulb line
- If you have a dry bulb temperature of 95 and a wet bulb temperature of 78, what is the relative humidity?
o The curve line at the intersection
o Look at the yellow dot
o 47%
- What is the humidity ratio?
o From the yellow line, move directly ro the right to get 0.017
- What is the specific humidity?
o 0.017 x 7,000 = 119
- What is the dew point?
o Go straight across to the elft from the yellow dot
o 72 degrees F
- What is the maximum amount of water that can be held at this point?
o We want the maximum amount of water that can be held at this 78 wet bulb
o From the tip of the left blue line at the 78 wet bulb point, go directly to the right to get 0.022
- If our dry bulb temp is 85 and the wet bulb temp is 73, what is the relative humidity? Humidity ratio? Specific humidity? Dew point? Maximum water held at 100% relative humidity?
o Relative humidity: 55%
o Humidity ratio: 0.013
o Specific humidity: 0.013 x 7,000 = 91
o Dew point: 65
o Maximum water held: 0.017 x 7,000 = 119
- What comprises the solar radiation the earth receives?
o Infrared: 49%
o Visible light: 42%
o UV radiation: 8%
- What does the amount of solar radiation received depend on?
o The angle of inclination of earth
- Does the solar radiation at the poles vary?
o The poles get the same amount of radiation all the time
- What do the differences in radiation cause?
o Differences in thermal energy
- What pressure results from warm air?
o High pressure
- What pressure results in storms?
o Low pressure
- In what air pressure is air more unstable?
o Low pressure
- What causes climates?
o The movement of pressure from high to low
o Warm currents move poleward
o Cold currents move towards the equator
- What are the vertical temperature gradients?
o Troposphere
o Tropopause
o Stratosphere
o Mesosphere
o Thermosphere
o Ionosphere
- What are the characteristics of the troposphere?
o Unstable, leads to bad weather
o In the troposphere, the temperature decreases with increasing altitude
- What are the characteristics of the tropopause?
o Isothermic: the temperature pauses
o Stable
- What are the characteristics of the stratosphere?
o Temperature increases with altitude due to UV absorption by ozone
o Relatively stable
- What are the characteristics of the Mesosphere?
o Temperature deceases with altitude
o Rapid vertical mixing as a result of cold temperature
- Which sphere has the coldest temperatures?
o Stratosphere
- What are the characteristics of the thermosphere?
o High temperatures due to absorption of short wavelength radiation
- What is the characteristics of the ionosphere?
o Layer of atmosphere with ionic version of oxygen and nitrogen molecules
- What happens to atmospheric pressure as the temperature increases?
o Atmospheric pressure increases due to the kinetic energy of the molecules
- What is standard atmosphere?
o 760 mm Hg
o 1.01325 x 105 Pa
- What kind of weather does high pressure lead to?
o Warmer, dry weather
- What kind of weather does low pressure lead to?
o Colder, more unstable weather
- What is air pollution?
o The introduction of harmful substances or products into the environment
- What is natural air pollution?
o Pollution that occurs as a result of natural processes like volcanic activity, fires, decomposition, and ocean spray
- T/F. Natural pollution is the greatest pollutant.
o True, but the effect as a pollutant is minimal
- What are some causes of anthropogenic air pollution?
o Deforestation
o Industrial revolution
- What is haze?
o Particles suspended in air, reducing visibility by scattering light
- What is fog?
o Water droplets suspended in the atmosphere in the vicinity of the earth’s surface that affect visibility
- What is smog?
o Fog or haze combined with smoke and other atmospheric pollutants
- What is a primary pollutant?
o Pollutants from transportation, industry, waste disposal, etc.
- What are the two types of primary pollutants?
o Mobile
o Stationary
- What are mobile pollutants?
o Pollutants that move such as automobiles, train, and planes
- What are stationary pollutants?
o Pollutants that do not move such as power plants and industrial factories
- What are the two types of sources for pollutants?
o Point source
o Area source
- To limit air pollution, what did the CAA require?
o The development of the National Ambient Air Quality Standards (NAAQS)
- What is the National Ambient Air Quality Standard (NAAQS)?
o The standard that sets limits on 6 “criteria” air pollutants
- What are the 6 criteria air pollutants se by NAAQS?
o CO
o NO2
o Pb
o O3
o PM10
o PM2.5
o VOC
- Even though we are significantly reducing emissions, why do we still see an increase in current emissions?
o Increase in population
o Increase in power use
o Increase in cars on the road
- What are the anthropogenic sources of CO2¬?
o Fossil fuel use
o Land conversion
- What is land conversion?
o The shift of vegetation into the ground
- What are some examples of CO2 sinks?
o Deep sea
o Ocean sediment
o Fossil fuel reserves
- Why do sinks contribute to the pollution problem?
o When the sinks are disturbed, CO2 is brought into the atmosphere
- Where do emissions of carbon monoxide come from?
o Biomass burning
o Combustion
- What type of combustion results carbon monoxide release into the atmosphere?
o Incomplete combustion
- How does incomplete combustion result in carbon monoxide release into the environment?
o During combustion, CO reacts with oxygen to produce CO2
o If there is insufficient O2, then there is excess CO
- Which has higher levels of carbon monoxide ambient concentrations or background levels in urban areas due to vehicle usage?
o Ambient concentrations
- How do carbon monoxide sinks occur?
o Uptake by soil
o Conversion to O3 in the troposphere
- How does methane emission occur?
o Digestion of cellulose by livestock
o Decomposition of organic material
o Coal
o Refineries
- How do methane sinks occur?
o Methane conversion to water and a methyl group when there is a reaction with a hydroxyl group
- What happens if there is too much carbon monoxide in the presence of methane?
o Carbon monoxide also uses hydroxyl groups that will reduce the ability for methane to react with it, increasing methane concentrations
- How are sulfur compounds emitted into the environment?
o Volcanoes
o Combustion of fuel and biomass
o Sulfur-containing metal ores
- Why has sulfur concentrations decreased over the years?
o Control technologies on industries
o Reduction of coal use
- What are scrubbers?
o Attached to industrial buildings
o This is a limestone and water mixture that combines with sulfur to produce Gypsums which can then be recycled
- Why can nitrogen be bad in the atmosphere if it is naturally found in high concentrations?
o The precursor molecules leads to various NOX which can cause ozone depletion, global warming, and oxidation of biogenic VOCs like isoprene
- What is aerodynamic equivalent diameter (AED)?
o This is how we get the nomenclature for PM
o A method of standardization since all particles come in different shapes and sizes
o AED is based on the diameter of a spherical particle with a density of 1 g/cm3
o Particles with an AED of PM2.5, regardless of actual shape will settle at the same velocity as a spherical particles with 2.5 diameter
- What are the two classes that atmospheric particles can be divided in?
o Coarse particles
o Fine particles
- How are coarse particles generated?
o Mechanical means such as jack hammering and erosion
- What kind of compounds tend to make up ultrafine particles?
o Sulfate and organic compounds
- What is Aitken range?
o Produced by combustion, coagulation, and condensation of gas-phase particulates
- What is dispersion?
o Pollutants mixing with air resulting in lower ground-level concentrations (dilution)
- What is transport?
o Process by which air motions carry pollution from one region to another
- What is deposition?
o Transfer of gas and particulate-phase substances to vegetation, water, and other surfaces (removal)
- When pollutants are emitted into the atmosphere from a point or area source, what happens?
o Pollutents are dispersed (diluted) by air moving horizontally and vertically
o Transported from one location to another
- Why is transport important?
o Transport enhances dilution and can allow mixing of various pollutants from otherwise distant sources
- Where does dispersion and transport occur?
o Planetary boundary layer (PBL)
- What are the four scales of motion?
o Microscale
o Mesoscale
o Synoptic scale
o Global scale
- What is the microscale?
o Local, no more than 24 hs
o Tornados, rainbos, soil temperature, tracking of air pollution
o What you see
- What is the mesoscale?
o A few days
o Includes thunderstorms, convective processes
- What is synoptic scale?
o Many days
o Thousands of kilometers
o Hurricanes, fronts, high and low pressure systems
- What is the global scale?
o Weeks to months
o Large areas of the globe
o Polar jet streams, trade winds, El Nino
- What is the mixing of the planetary boundary layer?
o The PBL is relatively well-mixed on a large scale
- What is the mixing on the local (microscale)?
o Not great mixing
o Air emissions can lead to harmful health conditions based on prevailing atmospheric conditions
- What conditions affect mixing?
o Wind
o Turbulence
o Stability
o Inversions
- What is wind speed affected by?
o Temperature and surface roughness
- What is the wind surrounding urban areas?
o Urban areas tend to have lower velocity winds than suburban and rural due to more surface roughness
- Why do we like large wind velocities?
o Greater wind velocities allow for more air volume to aid in dispersing of contaminants
- What is the rule of thumb for wind and dilution?
o Dilution is inversely proportional to wind speed
o If wind speed doubles, concentration of pollutants is cut in half
- What is turbulence?
o Eddies that are produced by mechanical or thermal forces
- What is turbulence on the micro scale?
o Air movement over shorter time scales
- What is turbulence on the meso scale?
o Air movement by wind
- What causes mechanical turbulence?
o Turbulence caused by wind moving around structures and vegetation
- What causes thermal turbulence?
o Heating and cooling of air near the surface
- When does turbulence tend to occur?
o Both forms of turbulence occurs during daylight
- How does turbulence affect dispersion?
o Turbulence enhances dispersion and decreases concentration of pollutants
- How does stability affect dispersion?
o As stability increases, dispersion decreases
- What is lapse rate?
o The rate of temperature change with height
- What is the tropospheric lapse rate?
o -6.5 C/km
- What is adiabatic lapse rate?
o Theoretical change of temperature with height when no heat energy is transferred to air
o -10 C/km
- What are the characteristics of a near adiabatic lapse rate?
o Small decrease in temp with height
o Air cools as it expands but still close to adiabatic lapse rate
o Found in cloudy or windy conditions
o Dispersion is relatively good
- What are the characteristics of a super adiabatic lapse rate?
o Greater decrease in temp with height than A
o Parcel of air will rise rapidly
o Very unstable, strong vertical air motion
o Found on clear days with light winds
o Dispersion is excellent
- What are the characteristics of an isothermal layer?
o Temperature does not change with heigh
o Parcel of air rises slowly
o Stable atmosphere
o Moderate dispersion
- What are the characteristics of an inversion layer?
o Temperature increases with heigh
o Inverted temperature changes
o Very stable atmosphere with no vertical air motion
o Found on clear nights with light winds
o Dispersion is poor
What happens during an inversion?
o When lapse rates are positive
o Temperature increases with height
- What are the four types of inversions?
o Frontal
o Advective
o Radiational
o Subsidence
- What is a frontal inversion?
o Warm front flows over cold front
o Limited effect on air quality
- What is an advective inversion?
o Refers to horizontal transfer
o Warm air flows over cold surface
o Advective is day to day inversion
- What causes radiational inversions?
o Colling of the ground
- When do radiational inversions form?
o On clear nights
- When do radiational inversion break up?
o As the sun starts to warm up the ground and air
- T/F. Radiational inversions on flat terrain greatly impact the air quality.
o False, it has limited impact
- What type of inversion has the greatest impact on river valleys?
o Radiational inversions
o More important in valleys than in flat terrain
- What parts of a stack impact air quality?
o Height of stack
- What causes subsidence inversion?
o Subsidence of air from widespread high pressure system
- Where is subsidence inversion common?
o Northern regions and subtropical areas
- When do subsidence inversions affect air quality?
o When close to the ground
- What do point source plumes release?
o A combination of gas-vapor particulates
- Which part of the plum will settle close to the source?
o Particulates >20 micrometers
- Which particulates will disperse similarly to gases and vapors from a plume?
o AED<1
- How do pollutants move?
o From high concentrations to low concentrations and dispersion may occur by diffusion
- What direction do plumes spread?
o Vertically and horizontally
- What part of the stack is dispersion affected by?
o Physical height
o Plume rise
- What is plume rise?
o The distance from the top of the stack to the center of the plume (horizontal plume)
- What is effective stack height?
o Height from the base of the stack to the center of the plume
- What happens when you increase stack height?
o Dispersion increases
- How do high winds affect stack height?
o High winds can decrease the effective stack height by decreasing plume rise, and the distance to where the contaminant may be brought to the ground
- What are the three major types of plumes?
o Coning
o Fanning
o Looping
- When does a coning plume form?
o Lapse rates are neutral to isothermal
o Cloudy or windy days, or at night
o Slightly unstable air
- When do fanning plumes form?
o Stable conditions
o Little vertical movement, but can have great horizontal movement
- When do looping plumes form?
o Lapse rate is superadiabatic
o Calm winds
o Looping motion comes from rise and fall of air currents
- What is dry deposition?
o Direct transfer of substances to water, vegetation