Composition of the present atmosphere and its evolution

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ATOC 4720 class 42 Final review

• Composition of the present atmosphere and its
  evolution
• The first two major composition of the
  present atmosphere

75.51 by mass
23.14 by mass
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Evolution The earth formed first, and its
present atmosphere are believed
to be evolved from the volatile
substance from volcanic
eruption. Major composition of the raw
atmosphere due to volcanic eruption 85
, and 10
light
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2. The distribution of atmospheric pressure and
density
Where
7-8 km scale height
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3. The fair weather elecric field and charged
particles
Charged Particles important for lightening,
reflection of radio
waves, fair weather electric field, etc

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4. Temperature distribution with height
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5. Gas laws
For a unit mass dry air
For unit mass of moist air
Where
Virtual temperature
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6. The hydrostatic equation
Large scale atmospheric motions satisfy
hydrostatic balance. Balance between the upward
PGF and the downward gravitational Force.
PGF
Gravity
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7. The geopotential and geopotential height
the work that must be done against the earhts
Gravitational field in order to raise a mass of
1kg From sea level to that point. J/kg.
Geopotential height
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8. The hypsometric equation
Warm air thicker Cold air thinner
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9. The first law of thermodynamics
Applies for both diabetic and adiabatic
processes. Diabetic heat absorbed by a
substance is used either to increase
its internal energy or used to do external
work. Adiabatic dq0. 1 Adiabatic expansion
2 Adiabetic
compression
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10. Lifting condensation level (LCL)
The lifting condensation level is defined as the
level to which a parcel of moist air can be
lifted adiabatically before it becomes saturated
with respect to a plane surface of water.
LCL -- well defined cloud base.
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11. Static stability and level of free convection
Conditionally unstable
Level of free convection
x
Height
LCL
Temperature
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unstable
T1T1e then T2gtT2e
T2e
T2
T1
T2e
stable
Convectively unstable T inversion layer
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12. Atmospheric aerosols
Effects on cloud and precipitation CCN Should
know why. Homogeneous nucleation is difficult to
grow big Atmoshperic electricity, radiation,
chemistry.
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13. Hurricanes
Dynamics CISK Air/sea interaction Thermally
direct Circulation Available Potential
Energy (PE) Is converted to Kinetic energy
(KE). Maintenance warm Core maintenance-- PE--K
E
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14. Radiation
Wien displacement law
Stefan-Boltzmann law
Kirchhoffs law
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15. The global energy balance
Top 100 in 30 reflection 3826 atm
emits 6 IR emits Earth
Atm 163 SW abs 15 IR abs 7 abs
sensible 23 abs latent 38 emits molecules
26 emits clouds Surface 51 in
23 latent 7 sensible
21 IR
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16. Photoionization, photodissociation of oxygen,
and fromation of ozone layer
Upper thermosphere, photoionization of molecules
and atoms Produces ionosphere, absorbs solar
radiation
Photodissociation above 100km
Ozone is not formed in this high level however
mean free path Large, 3 body collision chance is
small.
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20-60km O is trace but important for ozone
formation. Three body clission chance is large
because mean free Path is small.
Then,
Reduce UV, Ozone layer protects the earth plants
etc.