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Atmosphere
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- 1AtmosphereConsists of gases (N2-78%, 21% O2, and Ar 0.9%) and lower extent of solids and liquids. Includes Trace gases with constant conc (noble gases), and traces gases with variable conc (Co2, CH4, H2, N2O, O3, H2O, NO2, NH3, SO2, H2S).
GHGs (CO2, N2O, and CH4) are increasing and can absorb longwave IR emitted by Earth's surface trapping heat in the atm (global warming). - 2ToposphereFirst layer in the atm. Thin layer (10 km thick), 2% of atms thickness. Majority of the water is in the troposphere. 75% of total atm's mass. Thicker at equator, and narrow at the poles. Accounts for wind and clouds.
Inc h, dec T, dec P. - 3StratosphereAbove troposphere.
Lower Stratosphere: T is constant at -55C.
Upper: T inc, P dec. Ozone layer is contained here which absorbs the UV light and releases energy increasing the T. Highly stable compounds accumulate in the Stratosphere (ex. CFCs). - 4Mesospheredec T, no ozone to warm up the layer. Significant amounts of CO2--radiative loss--any heat is released to the sky.
- 5Thermosphereinc T, oxygen and nitrogen absorbs UV light/solar radiation, and heats up.
- 6ChemosphereStratosphere + Mesosphere
Chemical reactions initiated by UV light (photochemical reactions) - 7IonosphereSolar radiation can ionize many compounds.
- 8Adiabatic Lapse RateRate at which the temperature of an air parcel changes in response to the compression/expansion associated with elevation change. Process is adiabatic (no heat exchange occurs the air parcel and its surroundings).
P dec, air parcel expands doing some work. No heat transfer occurs, resulting in T dec, since energy is lost from expansion.
ALR for dry atm is 9.8C/1000m - 9ALR
- 10Wet ALRAdiabatic cooling due to increasing altitude for wet air.
3.6-5.5C/1000m, lower than dry because of water vapor condensation. Condensation releases heat causing air parcel to stay warm. - 11Actual Atmospheric Lapse RateDepends on heating, mixing, and wet adiabatic processes.
~7C/1000m. It corresponds to the air surrounding the air parcel. - 12Stable AtmNot much mixing occurs.
Adiabatic LR > Actual LR
TB>TA
Density A>Density B
Air parcel at point A will sink because its density is heavier than at point B. Results in no mixing. - 13Stable Atm
- 14Unstable AtmLots of mixing occurs.
Actual LR > Adiabatic LR
TA>TB
Density A < Density B
Parcel will keep climbing up and air inversion occurs.
Air Inversion: inc h, inc T of air parcel, temperature near the ground is cold, cold air gets trapped, and cannot travel up, as the temperature is greater at the top. Density will be high and get an accumulation of pollutants. - 15Atmospheric Stability throughout the Day
- 16Early AftjernoonGround is warm, inc h, then temperature drops. Big layer participating in mixing.
- 17Early MorningGround is cold. Inc h, increases temperature, but then drops after some height before sunrise. Air inversion occurs here, as T inc with height.
- 18Mid MorningA. High T, low density.
B. Low T, high density.
Between A and B get some mixing, and as time elapses, the height of mixing increases. - 19Air PollutionPresence of contaminants in such quantities (conc) and of such duration as may be or may tend to be injurious to human, plant, or animal life, or property or which unreasonably interferes with comfortable enjoyment of life, property, or the conduct of business.
- 20Primary Air PollutantsEmitted directly from the source. Ex. VOC, CO, SO2, NO.
- 21Secondary Air PollutantsFormed in the atmosphere by chemical reaction between primary pollutants and chemical species normally found in the atmosphere. Ex. VOC + NOx >>>(UV)>>>> O3 + CH2O
- 22Natural SourcesVolcano, vegetation emission, forest fire
- 23Anthropogenic SourcesFuel combustion, industrial processes, transportation, agricultural activities, waste disposal, carbon pollution
- 24Gaseous Atmospheric Pollutants (9)1. Sulfur Oxides (SOx)
2. Ozone (O3)
3. Carbon Monoxide (CO)
4. Nitrogen Oxides (NOx)
5. Volatile Organic Compounds (VOCs)
6. Greenhouse Gases (GHGs)
7. Ammonia (NH3)
8. Mercury (Hg)
9. Lead (Pb) - 25SOxSulfur Oxides: responsible for acid rain.
Irritates: nose, throat, airways.
Natural sources: volcanoes, wetlands, oceans.
Anthropogenic: coal, ore roasting, low-grade oil combustion.
65% dec since 1990s by the mining industry. - 26Ozone (O3)Main component of photochemical smog.
Damages lung, respiratory issues, throat, and eye.
Secondary pollutant.
VOCs + NO2 >>UV>> O3 + other
O2 >>UV>> O3 - 27COPoisonous, colorless, and odorless gas.
Causes headaches, dizziness, vomiting, nausea, and death.
Natural sources: bacterial activity and wildfire.
Anthro: incomplete combustion
CO + O2 >>> CO2 - 28NOxNitrogen Oxides (NO and NO2) causes acid deposition, ozone depletion, photochemical smog.
Damages resiparatory pathways (lung) and causes wheezing, and coughing.
Natural: bacterial activity, wildfire, lightning.
Anthropogenic: high-temperature combustion--natural gas not coal.
20% decrease since the 1990s. - 29VOCsCauses photochemical smog.
Eye, nose and throat irritation, headache, nausea, damage to liver, kidney, and central nervous system.
Natural: wildfires and plants.
Anthropogenic: paints, solvents, and fossil fuels.
40% decrease from 1990s by petroleum industry. - 30GHGsGases that trap heat in the atm
Responsible for GW
Not an air pollutant wrt conventional definition. - 31Ammonia
- 32Mercury
- 33Lead
- 34Particulate Atmospheric PollutantsSolids, Liquids, or Solids coated with liquid.
Coarse: dp>2um
Fine: 0.1um - 35Ultrafine ParticlesOriginates from the condensation of hot vapor and are highly reactive forming aggregates. Can be removed by coagulation.
Short life times - 36Fine ParticlesOriginates from aggregates of smaller particles and are not highly reactive. Slow to settle in the atmosphere.
Long life times and removed through rain. - 37Coarse ParticlesLow reactivity, fast to settle because they are large and therefore have a short lifetime. Not air born in the atmosphere, but still remains in the environment.
- 38Effects of Particles Sizes (6)1. Reactivity: Dec dp increases reactivity (Ultrafine is first)
2. Visibility (light scattering): Fine is first because of their long life-times
3. Earth's heat balance: Blocked sunlight (fine, due to long lifetimes)
4. Effectiveness of removal mechanisms: size of the particle determines the type of technology required for removal.
Large requires cyclone
Small requires filter and ESP
5. Residence time in the atm:
Fine has the highest residence time
6. Health Impacts: Fine b/c of residence time. - 39Physical Removal of Chemicals (3)
- 40ImpactionWhen air containing particles moves past objects such as vegetation and buildings and collides with the objects.
1. Impaction (large)
2. Interception (medium)
3. Diffusion (small) - 41Wet Deposition of Particles1. Rain out/Nucleation: Particles serve as nucleation sites for water droplet or ice crystal formation.
2. Washout/Collision: incorporation into already-formed water droplets within a cloud. - 42Atmospheric Chemical Reactions1. High potential for chemical oxidation
2. Exposed to sunlight-photochemistry
3. Biodegradation is irrelevant
4. Particles can also help catalyze reactions - 43Oxidation in the AtmReactive Oxygen Species (ROS) participate in atmospheric chemical reactions. Ex. O3
Tropospheric O3 is a pollutant, though stratospheric O3 blocks UV radiation and is beneficial. Refer to slides for last 10 slides.
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- Descripción
- Engineering Fichas sobre Atmosphere, creado por Aaysha Babaria el 14/04/2019.
- Creado por
- Aaysha Babaria
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