Ozone depletion Flashcards
1
Q
Order the UV based on wavelength
A
- highest - UVA (gets all the way through)
- middle - UVB (ozone layer absorbs lots of it)
- lowest - UVC (non gets all the way through)
2
Q
What is the term for ‘a combination of active processes that cancel out each other’s effects so that there is no overall change’
A
- dynamic equilibrium
3
Q
What are some effects of UVB on living organisms
A
- skin cancer
- cataracts
- leaf tissue damage on plants - decreases photosynthesis
4
Q
What is a halogen
A
- a group 7 element
- they are highly reactive and are toxic
5
Q
What pollutant gas contains chlorine
A
- CFC’s - chloroflurocarbons
6
Q
What is the history of CFC’s
A
- after WWII - CFC’s were used as propellants for bug sprays, paints etc
- during 1950’s and 60’s, CFC’s were used in air conditioning
7
Q
What are the properties of CFC’s
A
- non-flammable
- non-toxic
- persistant
8
Q
What are the sources for CFC’s
A
- fridges
- air conditioning
- paints
- fire extinguisher
9
Q
What was the Rowland-Molina principle
A
- was a 1974 paper suggesting that CFC’s could deplete the ozone layer
- hypothesised; CFC’s are persistant, some in troposphere are getting into stratosphere. there is enough energy in the stratosphere to set chlorine free from CFC molecules
10
Q
How do CFC’s deplete ozone in the stratosphere
A
- when CFC’s are exposed to UV, they break apart releasing chlorine atoms
- free Cl molecules react with O3 which slows down O3 formation
- chlorine monoxide reacts with free floating O2 that destroys O3
- this keeps on happening
- Cl reacts with other gases to form HCl
- they get put back in the troposphere and are washed away by rain
11
Q
Why is ozone depletion greater at polar regions
A
- extremely cold temperatures
- polar vortex winds
- stratospheric clouds
12
Q
What other gases cause ozone depletion
A
- HCFC’s
- halons
-bromine, fluorine and iodine
13
Q
How do scientists monitor ozone levels in the stratosphere
A
- collect air samples - use weather balloons
- ground bases surveys - equipment which measures how much UV radiation reaches earth’s surface
- satellites - shows cloud movement
14
Q
What is the Montreal Protocol
A
- global agreement to protect stratospheric ozone by phasing out production of ozone
- alternative to CFC’s is HFC’s
- they established a fund for LIC’s to make the phasing-out process easier for them
