Profile of the Earth

1
Profile of the Earths atmosphere
2
Atmospheric profile

• Exosphere
• From 5001,000 km (310620 mi 1,600,0003,300,000
  ft) up to 10,000 km (6,200 mi 33,000,000 ft),
  contain free-moving particles that may migrate
  into and out of the magnetosphere or the solar
  wind.
• Exobase
• Also known as the 'critical level', it is the
  lower boundary of the exosphere.
• Ionosphere
• The part of the atmosphere that is ionized by
  solar radiation stretches from 50 to 1,000 km (31
  to 620 mi 160,000 to 3,300,000 ft) and typically
  overlaps both the exosphere and the thermosphere.
  It plays an important part in atmospheric
  electricity and forms the inner edge of the
  magnetosphere. Because of its charged particles,
  it has practical importance because it
  influences, for example, radio propagation on the
  Earth. It is responsible for auroras.
• Thermopause
• The boundary above the thermosphere, it varies
  in height from 5001,000 km (310620 mi
  1,600,0003,300,000 ft).

3
Atmospheric profile

• Thermosphere
• From 8085 km (5053 mi 260,000280,000 ft) to
  over 640 km (400 mi 2,100,000 ft), temperature
  increasing with height. Although the temperature
  can rise to 1,500 C (2,730 F), a person would
  not feel warm because of the extremely low
  pressure. The International Space Station orbits
  in this layer, between 320 and 380 km (200 and
  240 mi).
• Mesopause
• The temperature minimum at the boundary between
  the thermosphere and the mesosphere. It is the
  coldest place on Earth, with a temperature of
  -100 C (-148.0 F 173.1 K).
• Mesosphere
• From the Greek word meaning middle. The
  mesosphere extends from about 50 km (31 mi
  160,000 ft) to the range of 8085 km (5053 mi
  260,000280,000 ft). Temperature decreases with
  height, reaching -100 C (-148.0 F 173.1 K) in
  the upper mesosphere. This is also where most
  meteors burn up when entering the atmosphere.

4
Atmospheric profile

• Stratopause The boundary between the mesosphere
  and the stratosphere, typically 50 to 55
• Stratosphere
• From the Latin word "stratus" meaning spreading
  out. The stratosphere extends from the
  troposphere's 717 km (4.311 mi 23,00056,000
  ft) range to about 51 km (32 mi 170,000 ft).
  Temperature increases with height. The
  stratosphere contains the ozone layer, the part
  of the Earth's atmosphere which contains
  relatively high concentrations of ozone. It is
  mainly located in the lower portion of the
  stratosphere from approximately 1535 km above
  Earth's surface, though the thickness varies
  seasonally and geographically.
• Ozone Layer
• Though part of the Stratosphere, the ozone layer
  is considered as a layer of the Earth's
  atmosphere in itself because its physical and
  chemical composition is far different from the
  Stratosphere. Ozone (O3) in the Earth's
  stratosphere is created by ultraviolet light
  striking oxygen molecules containing two oxygen
  atoms (O2), splitting them into individual oxygen
  atoms (atomic oxygen) the atomic oxygen then
  combines with unbroken O2 to create O3. O3 is
  unstable (although, in the stratosphere,
  long-lived) and when ultraviolet light hits ozone
  it splits into a molecule of O2 and an atom of
  atomic oxygen, a continuing process called the
  ozone-oxygen cycle. This occurs in the ozone
  layer, the region from about 10 to 50 km (33,000
  to 160,000 ft) above Earth's surface. About 90
  of the ozone in our atmosphere is contained in
  the stratosphere.

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Atmospheric profile

• Tropopause
• The boundary between the stratosphere and
  troposphere.
• Troposphere
• From the Greek word meaning to turn or change.
  The troposphere is the lowest layer of the
  atmosphere it begins at the surface and extends
  to between 7 km (23,000 ft) at the poles and 17
  km (56,000 ft) at the equator, with some
  variation due to weather factors. The troposphere
  contains roughly 80 of the total mass of the
  atmosphere. Fifty percent of the total mass of
  the atmosphere is located in the lower 5.6 km
  (18,000 ft) of the troposphere.
• The average temperature of the atmosphere at the
  surface of Earth is 20 C (68 F 293 K).12

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Thermal inversions and smog

• The temperature of the atmosphere decreases up to
  about 10,000 ft
• So warm air will naturally rise, including warm
  polluted air. Which means pollution from cars and
  factories should rise up into the atmosphere and
  be disperse where it causes no immediate effects
  on people
• Unless a condition occurs which inhibits the
  upward movement of warm air

7
Adiabatic Lapse rate

• The name given to the temperature-altitude
  relationship in the lower atmosphere
• Adiabatic means no energy is gained or loss by a
  volume of gas
• Lapse means the temperature decreases with
  increasing altitude
• So warm air will rise and cool at a specific
  rate. It will not exchange energy with the
  surrounding air and will expand because the air
  pressure surrounding it decreases as it rises.

8
ALR and inversions

• Now what happens if the meteorological conditions
  change the temperature height profile?
• If the temperature decrease faster with height
  than the ALR, then warm air rises indefinitely in
  to the atmosphere. This provides good mixing and
  naturally removes pollutants.
• If the temperature increases with height, warm
  air and the pollution in it is trapped near the
  surface. This is called a temperature inversion.
• Pollutants are trapped near the surface-causes
  smog

9
SMOG

• Smoky Fog
• First coined by Dr. Henry Antoine Des Voeux in
  his 1905 paper, "Fog and Smoke, in which he was
  describing the fog seen in London, which had
  different properties than the fog seen in the
  English countryside.
• Classic smog-primarily composed of particulates
  and sulfur oxides from coal burning-London famous
  for its thick smogs or peasoupers as they are
  called.
• Immortalized in literature and art

10
Smog

• Photochemical smog-more modern fog, results from
  the interaction of the sun and automobile
  emissions.
• Mixture includes
• Carbon monoxide
• nitrogen oxides, such as nitrogen dioxide
• tropospheric ozone
• volatile organic compounds (VOCs)
• peroxyacyl nitrates (PAN)
• aldehydes (R'O)

11
Carbon monoxide

• Most serious of all the pollutants
• Formed from the incomplete combustion of carbon
• Prime source is the gasoline fuel internal
  combustion engine
• Dangerous gas-colorless and ordorless
• It combines with hemoglobin in the bloodstream
• Hemoglobin is a protein in the bloodstream that
  carries oxygen from the lungs to tissues
• CO is more likely to combines with hemoglobin
  than oxygen, so when it gets in the blood stream
  it inhibits oxygen flow
• Causes suffocation

12
Concentration and exposure

• Like many pollutants, the effect of CO on a
  person is a function of both the concentration
  and exposure level
• Concentration is describe by ppm- parts per
  million
• PPM-Denotes one part per 1,000,000 parts, one
  part in 106, and a value of 1 106. This is
  equivalent to one drop of water diluted into 50
  liters (roughly the fuel tank capacity of a
  compact car), or one second of time in
  approximately 11½ days.
• These are units of proportionality
• So for CO, after 10 hours
• 100ppm you have a headaches and are unable to
  think clearly
• 300ppm nausea and loss of consciousness
• 600 ppm death
• If the concentration is 1000 ppm, loss of
  consciousness occurs in about 1 hours and death
  in 4
• Not just a problem from cars, CO is also released
  in in home gas appliances
• Poses an increasing danger as homes are becoming
  more environmentally sealed to save energy
• Gas appliances need proper ventilation

13
Controls on CO and other emissions

• Environmental Protection Agency
• Government agency that sets air quality standards
• Standards are called the National Ambient Air
  Quality Standards (NAAQS)
• Set by the Clean Air Act of 1970, and amended in
  1990.
• Clear Skies Act-proposed by the Bush
  administration in 2003 not passed
• Attempt to limit sulfur dioxide, nitrogen oxide
  and mercury emissions from power plants
• Criticized as weakening the clean air act by
• Weakens the current cap on nitrogen oxide
  pollution levels from 1.25 million tons to 2.1
  million tons, allowing 68 more NOx pollution.
• Delays the improvement of sulfur dioxide (SO2)
  pollution levels compared to the Clean Air Act
  requirements.
• Delays enforcement of smog-and-soot pollution
  standards until 2015.

14
Other pollutants Nitrogen oxides

• Reddish brown gas that is responsible for the
  color of smog
• Produced in internal combustion engines and coal
  plants
• Can react with water vapor to produce nitric
  acid-leads to acid rain (we will come back to
  this)
• Nitrogen dioxide reacts with sunlight to produce
  nitrogen oxide and oxygen
• This oxygen reactions with molecular oxygen to
  produce ozone
• This ozone can react with nitrogen oxide and
  produce nitrogen dioxide and molecular oxygen
• At 0.5 ppm it can be smelled, 5 ppm it effects
  the respiratory system, 20-50 ppm lung liver and
  heart damage can occur

15
Other pollutants-hydrocarbons

• Recall hydrocarbons are compounds made of carbon
  and hydrogen
• Released into the atmosphere via
• Auto exhaust
• Evaporation of gasoline in the process of its
  refinement, productions and handling
• Chemical manufacturing
• Manufacturing of dry cleaning fluids, ink and
  paint manufacturing releases organic solvents
• Industrial dryers, ovens and incineration of
  materials
• Hydrocarbons combine with ozone (formed from the
  nitrogen dioxide) to form complex molecules of
  hydrogen, oxygen and carbon called peroxyacyl
  nitrates or PANs.

16
Effects of Photochemical smog

• PANs result in eye irritation, damage to
  vegetation and skin cancer
• Aggravates respiratory conditions
• Suggestions that is results in lung cancer and
  pulmonary disease
• Plant diseases
• Smog injury-cells on the upper part of the leaf
  collapse. The leaf looks water soaked
• Grape stipple-blotched appearance of leaves,
  particularly tobacco or grape leaves
• Oxidants cause cracking and disintegration of
  stretched rubber, paints and fabrics loose their
  color and strength
• Visibility issues

17
Sulfur dioxide

• Colorless, nonflammable gas
• Produced in the burning of fossil fuels
• Coal and oil burning plants
• Smelting operations
• Natural sources include decay of organic matter
• There are natural processes that remove it from
  the atmosphere, these include dry deposition
  (random air motions deposit the sulfur on the
  ground) , plant uptake and precipitation

18
Effects of sulfur dioxide

• Respiratory illness-including lung cancer
• Cardiovascular illness
• Marble, limestone and mortar dissolved
• Protective coatings on metal loose their
  protective ability
• Plant damage
• Note-effects are hard to distinguish from the
  effects of sulfuric acid, but the sulfur dioxide
  helps to form sulfuric acid in the environment