Introduction Flashcards
(17 cards)
Evolution atmosphere
- Formation planets (dust, meteorites and gravity)
- Volcanic activity on earth 4.6 billion years ago (85-100C mostly water vapour 85%, CO2 10, N2 S SO2 H2S)
- Reduction of volcanic activity 3.8 billion years ago (atmosphere cooled rain and clouds formed)
- Photosynthesis and life 3.5 billion yrs (net production oxygen up and CO2 down)
- Continental drift
Present atmosphere
Homosphere: altitude less than 80km, all gases have the same relative proportion almost everywhere
Heterosphere: greater than 80km, concentration of heavier gasses decreases with height increases (stratified)
Gases in atmosphere
N 78
O 21
A 0.93
CO2 0.041
Ozone 0.000007
Proportion in atmosphere does not mean importance ozone more important then nitrogen
Proportion is water vapour is highly variable~ polar less 1% tropical up to 4%
Geological time scale
Mammals ~ Cenozoic
Reptiles ~ Mesozoic
Ancient life ~ paleozoic
Earth changes with life
Thermal structure of atmosphere
Homosphere
- troposphere: where weather happens 0-10
- Tropopause: planes fly above to avoid weather
- ozone max: 25 km
- ozone layer: 10-50km
- stratosphere: 10-50
- stratopause: peak UV absorption, which is why it is so much warmer
- mesosphere: 50-85
Heterosphere
- mesopause: 85km
- thermosphere: 85-120
Ozone
Three atoms of oxygen (O3)
Not uniform distribution
Absorbs harmful UV radiation
Humans deplete ozone by adding chlorofluorocarbons (CFC)
-Montreal protocol and international policy has banned and now coming down quickly
Greenhouse gas so too much bad
Delayed until could find a substitute and then banned it
Southern Hemisphere~ ozone minimum
Aerosols
Tiny liquid or solid particles of various compositions that are suspended in the atmosphere Reflect incoming solar radiation Important in cloud formation Air pollutants: dust, ash salt, pollen Has decreased slightly but not for fires
Air pollutants
Sulphate oxides: fossil fuels decrease
Nitrogen oxides: trans, heat, fire decreased
Volatile organic compounds: photochemically reactive hydro compounds decreased
Carbon monoxide: imperfect combustion of carbon based fuels decreased
Ammonia: agriculture, trans, manu increased
Greenhouse gasses
H20, CO2, CH4, N2O, O3, CFC …
Significance not determined by relative abundance (small change in methane CH4 more important then CO2)
Absorb infrared from earth and convert to heat
Water vapour constrained by temp, powerful feedback loop with other gasses to make it the most powerful
Weather
State of atmosphere at a time
What you get
Climate
Statistics of weather, likelihood of particular weather event
What you expect
Vulnerability
Propensity or predisposition to be adversely affected. Encompasses a variety of concepts and elements including sensitivity susceptibility to harm and lack of capability to cope
Resilience
Capacity of social, economic, and environmental systems to cope with a hazardous event or trend or disturbance in ways that maintain their essential function, identity and structure
Adaptation
The process of adjustment to actual expected climate and its affects. Moderate or avoid harm or exploit beneficial opportunities
Adaptive capacity
The ability of systems, institutions, humans and other organisms to adjust to potential damage, to take advantage of opportunities, or to respond to consequences
How we are able to change
Mitigation
 A human intervention to reduce the sources or enhance the sinks of greenhouse gases. Human interventions to reduce the sources of other substance which may contribute to limiting climate change
Extreme events
Increase mean: prob dist shifts forward so more record hot temp
Increase variance: increase in hot and cold
Mean and variance: much more hot and record hot less change for cold
