Topic #1 Ozone in the Stratosphere

At the top of your paper you will find two grades.
The first is the content grade (you could earn up to 7 pts)
The second grade is the writing quality grade (you could earn up to 5 pts)

Here are some of the details and kinds of information we looked for when determining the content grade
Location and description of the ozone layer (up to 1.5 pts)
stratosphere 10-50 km altitude
temperature inversion, stable layer
densest ozone (12 ppm) at about 25 km altitude

UV<0.2 micrometers can cause (up to 1 pt)
skin cancer; cataracts; suppress the immune system; damaging to plants, animals, phytoplankton, may cool stratosphere

Natural production & destruction (0.5 pts)

manmade destruction (up to 2.5 pts)
NO, supersonic jets

CFCs, non-toxic, stable & unreactive, 50 to 100 yr lifetimes
one Cl atom can destroy 100,000 O3 molecules

3% drop in [O3] over heavily populated N. America 1979-1991
5 to 6% drop in stratospheric O3 since 1978 from more recent measurements

Montreal Protocol 1978, Copenhagen 1992
CFC replacements: HCFCs and HFCs

Ozone hole (up to 2.5 pts)
decrease in statospheric ozone above Antarctica Sept & Oct every year
discovered by British scientists, appeared to confirm predictions of Rowland and Molina

NOZE experiment 1986 & 1987
polar vortex, -121o F, PSCs cause reactions that destory ozone, Cl main culprit
no clear hole over N. Pole, not cold enough

Writing grades were awarded as follows:
Excellent (5 pts)
Free of grammatical and spelling errors, clear understanding and presentation of the material, material presented in an original and interesting way

Average (4 pts)
An occasional spelling or grammar error, organization and explanations not much different from what is found in the textbook (this makes it hard sometimes to judge how well you understood the material)

Below average (3 pts)
Quite a few spelling errors, some confusion or awkward sentence constructions, incomplete or inaccurate explanations of some of the material or superficial coverage of the material, the majority of the report is understandable.

Poor (2 pts)
Report is becoming hard to understand.