5.1-5.2: stratospheric ozone shield Flashcards
Ozone
layer of O3 in stratosphere; acts as a filter screening out solar UV rays
without ozone, life wouldn’t have evolved bc…
UV photons = energetic enough to photochemically harm w/o ozone layer (filter)
Cl (chlorine) =
ozone destroyer
CFCs =
deliver Cl to stratosphere
- Don’t react until UV photons break C-Cl bond (releasing Cl to destroy ozone)
Which chemicals associated with human activities destroy stratospheric ozone?
Cl and CFCs
What are chlorofluorocarbons and where were they primarily used?
- CFCs- gas used in refrigerants and aerosol cans
- Composed of organic compounds: carbon, fluorine, chlorine
- Primarily used for: propellants in aerosol cans, coolants
Why do CFCs cause ozone destruction?
- Bc they don’t react in troposphere; only in stratosphere
- Destroy ozone by: don’t react in troposphere –> when reach stratosphere UV photons break C-Cl bond
- Cl (chlorine) = major destroyer of ozone
How does the density of the atmosphere change with altitude?
↑ altitude = ↓ density
How does the temperature of the atmosphere change with altitude?
reverses several times:
- Up to ~10 km = temp ↓ w/ ↑ altitude
- Above ~10 km = temp ↑ w/ ↑ altitude
- Above ~50 km = temp ↓ w/ ↑ altitude
- Above ~90 km = temp ↑ w/ ↑ altitude
Lapse rate
slope of curve Temp vs. Altitude; reverses several times
Temperature inversion
change b/w (+)/(-) lapse rate; boundary b/w 2 layers of air
(+) lapse rate =
warm air rises, cool air sinks
(-) lapse rate =
stability; warm air overlies cool air
Dobson unit is used for…
measuring effective thickness of ozone layer @ particular location
1 Dobson unit = ____ thickness of O3 @ standard temp and pressure (25°C & 1 atm)
0.01 mm
