Atmospheric Composition and structure Flashcards
How much of the Earth’s mass is contained in the atmosphere?
0.0001%
What are the permanent gases?
- Nitrogen
- Oxygen
- Argon
Nitrogen makes up how much of the atmospheric composition?
78%
Oxygen makes up how much of the atmospheric composition?
21%
Argon makes up how much of the atmospheric composition?
0.93%
Nitrogen, oxygen, and argon make up how much of atmospheric composition?
99.93%
Variable gases include:
Water vapour (0.25%) carbon dioxide (0.037%), ozone (0.01%), methane (1.7ppm)
Aerosols:
small solid particles or liquid droplets in the air
Aerosol sources and effects:
- wind generated dust
- volcanic eruptions
- sea spray
- combustion by-products
Aerosol effects:
- reduce visibility
- health effects
- formation of cloud droplets
- RADIATIVE EFFECTS (Climate
Change)
Troposphere
- adjacent to surface
- vertical decrease in
temperature (-0.6°/100m) - generally well mixed
(convection and friction) - contains almost all of atmospheric water vapour
- all ‘weather phenomena’
take place within this
layer - average barometric
pressure at sea level:
1013 hPa
Tropopause
- top end of troposhere
- start of temp. inversion
- avg. barometric pressure: approx. 225 hPa (75%)
- avg. altitude dependent on
latitude - Poles: ~ 8km
- Equator: ~ 17km
- avg altitude dependent on
season:
Minimum: winter – spring
Maximum: summer - fall
Stratosphere
- bottom half: isothermal top half: temp. inversion \+0.25°/100m - ozone layer (≤10ppm): absorption of harmful UV radiation by O3 - geographic and spatial variability of ozone concentration and temp. - water vapour content extremely low - very little cloud formation
Stratopause
- top end of stratosphere
- end of temp. increase
- avg. altitude: approx. 50km
- avg. barometric pressure:
≤ 1hPa (99.9%)
Mesosphere
- temp. decrease with
height
approx. 0.2-0.3°/100m - vertical mixing possible
Thermosphere
- 85 – 800km
- continuous temp. increase due to absorption
of UV radiation
(difference between
temperature and heat) - consists primarily of
molecular and atomic
oxygen and nitrogen
Isobars
lines that connect all points with same pressure
Wind moves from ___ pressure to ___ pressure
high to low
what does wind speed depend on?
the pressure difference - greater the difference, the faster the wind
wind rises in ____ pressure and sinks in area of _______
rise in low
sink in high
a rise in low pressure creates…
clouds
a sink in high pressure makes…
clear skies
Ideal gas law:
describes relationship between pressure, density, and temperature
Pressure ____ with increasing height. Why?
decreases because as altitude increases, the number of air molecules decrease.
