Chapter 1A: Gases (and Particles) in the Atmosphere Flashcards
What is the atmospheric composition? (elements)
- 78% N2 and 21% O2
- Argon 0.93%
- Water vapour ranges from 0-4%
Why is the ozone (O3) layer important?
It shields the Earth from harmful ultraviolet radiation.
What are the effects of ozone (O3) at the surface?
It irritates eyes and respiratory tract.
It damages vegetation.
(It is the primary ingredient in photochemical fog).
How is ozone formed in the ozone layer?
O2 + UV-C → O + O
O + O2 → O3 + heat
O3 + UV-B → O2 + O
(UV-C: photons λ<240nm)
(UV-B: λ>320nm)
(Heat is released by this cycle, warming the stratosphere)
What is the importance of CO2?
It is used by plants for photosynthesis.
It absorbs a portion of the Earth’s outgoing long-wave radiation (infrared), and radiates (most of it) back to the surface. (GHG)
What is CO2 emitted from?
- Natural: Carbon dioxide enters the atmosphere through vegetation decay, volcanic eruptions and exhalations of
animal life. - Anthropogenic: Burning fossil fuels and deforestation
How is CO2 removed from the atmosphere?
Photosynthesis and deposition to oceans.
Why has the concentration of CO2 in the atmosphere been increasing?
Increasing burning of fossil fuels and deforestation.
What is the importance of water vapou (H2O)?
It stores latent heat; latent heat is then released in clouds which helps to drive the atmosphere’s general circulation. This also feeds thunderstorms and hurricanes in energy.
An important GHG.
Forms precipitation
Condenses to form cloud droplets.
What are aerosols?
They are suspended tiny (invisible) dust, salt, ash, soot and organic particles
Are aerosols important? (or just pollutants?)
Yes, they are important to cloud formation.
natural aerosols exist
What are some examples of gaseous pollutants?
sulfur dioxide (SO2), nitrogen oxides (NO, NO2), ozone (at surface), volatile organic compounds (VOC)
Where do aerosol particles come from? (primary particles)
They are directly emitted in particulate form:
- Biogenic / natural: mineral dust, sea sult, volcanic ash, forest fires, vegetation, …
- Anthropogenic: combustion of fossil fuels, biomass burning, traffic emissions, industry, …
Where do aerosol particles come from? (secondary particles)
They are formed in the air by gas-to-particle conversion processes.
ex: oxidation of volatile organic percursors by O3, OH, NO3, etc. , from incomplete combustion
What is the role of GHGs? (briefly)
GHGs absorb long wave radiation.
