ATOC 4720: class 4

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ATOC 4720 class 4

• Variable constituents
• Charged particles in the atmosphere

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Vertical distribution of P, density, mean free
path
Mean Free path
p
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Similarly,
H7km. Half mass of atmosphere 5.5km 99 30km.
Remarkably thin.
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Atmospheric composition as a function of height
2 processes
Molecular diffusion Mixing due to fluid motion
The level of transition from turbulent Mixing to
molecular diffusion is called The turbopause. The
well mixed region Below the turbopause is called
the Homosphere the region above is
called Heterosphere.
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1. Variable constituents
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Atmospheree composition
SUM
0-0.04
325ppm
0-12ppm
5ppm
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Water vapor sources and sinks
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• Main source evaporation from the earths surface
  is the main source of atmospheric water vapor
• Condensation which takes place in clouds is the
  main sink of atmospheric water vapor.
• Typical lifetime of a molecule of water vapor
  in the atmosphere is only a week.
• Concentration

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Ozone source and sink
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• Source Ozone is primarily generated by
  photochemical reactions in the layer between
  20-60 km polluted air small
• Sink At the earths surface, reaction with
  plants and dissolving in water.
• At 10-20 km, it is rather stable with a lifetime
  on the order of months.
• Long-term average, downward ozone flux

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2. Charged particles in the atmosphere

• Importance play a crucial role in geophysical
  phenomena lightening, reflection of radio waves,
  fluctuations in the geomagnetic field, etc.
• Sources (1) X-ray and UV radiation from the sun
  ionizes air molecules. All the suns ionizing
  radiation is absorbed above 60km (2) High-energy
  cosmic rays (3) Radioactive decay within the
  earths crust (4) Electric charges separated
  within clouds.

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Most electrons gt60km
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