O3 formation/depletion Flashcards
(29 cards)
what is ozone
3 allotropic O atoms, is highly reactive and a powerful oxidizer
what is UV-A
UV at 315-400 nm - 7% of sun (no harm)
what is UV-B
UV at 280-3115nm - 1.5% of sun (long term exposure harm)
what is UV-C
UV at <280nm - 0.5% of sun (extreme harm)
is ozone good at blocking UV-B rays?
no it doesn’t absorb the right wavelength to block UV-B
what type of Thymine dimers are there
T+T, T+C
Where is the ozone layer
in the stratosphere 23km above the Earth
How should O3 be measured
measured with laser A (308nm absorbable) and laser B (351nm unabsorbable) and the difference is the contration seen
what is Dobson unit
amount of ozone needed to cover 0.01mm on the Earth’s surface @0.0C (1DU = 0.01mm)
what is the average DU for ozone
300 DU
what is the Du at the poles
450 DU
what is the Du at the equator
220 DU
When is the ozone hole a great concern
when the DU is below 220DU (lowest is 85DU)
what are the seasonal ozone changes
higher in fall/winter - no tress to absorb
lower in spring/summer - photosynthesis happening
what does sunscreen protect from
UV-B
what does SPF stand for
sun protection factor: how much UV-B is blocked
how is SPF measured
15 SPF mean you can stay that much longer in the song
what are CFCs and what were they used for
there are chlorofluorocarbons from the 1930s it was used as a refrigerant in fridges and ACs
what is Feron
it is a patented CFC
disadvantages of CFC
heavy into troposphere, they go through photolytic decomp (Cl radicals are bad)
what is ODP
amount of ozone depletion
ODP formula
1kg of chem comparison/1kg of CFC-11
what don’t F radicals form readily in the atmosphere
because are smaller and closer means holding onto there e-
advantages of HCFCs/HCFs
lower ODP, lower lifetime, replaces CFCs
