STRATOSPHERIC OZONE

PSC

is a polar stratospheric cloud. within these clouds, ice crystals form. because temps gets so cold, temps drop to minus 100 degrees Fahrenheit. the nitrogen and water vapor in the air freezes. all this is happening in the winter, above Antarctica. process -air from upper stratosphere and lower mesosphere descend into polar vortex -strong circulating winds isolate the cold air in the middle and lower stratosphere over Antarctica -region of very cold air forms in vortex

GCC and O3

-Global climate change can be influencing ozone recovery -Temperature retention in troposphere causes cooling stratosphere -Increased persistence of PSCs

Describe the process that takes a CFC to free chlorine

-Ice crystals provide a surface area for those CRS to stick. -Difference is that the nitrogen is in the ice -Chlorine gas will come off the surface of the ice crystal and float around in the atmosphere, still in the dead of winter where there is no sunlight -When spring comes and the sun shines, the CL2 gas it becomes 2 free chlorine -Free chlorine is capable of breaking up ozone -Chlorine is when the process of ozone depletion occurs -Chlorine meets ozone and strips the ozone of one of its oxygen CL + O3 --> CLO + o2 CLO+o3--> CL + 202

molina and rowland find CFC's-1974

-found CFC's in the atmosphere - developed the ozone depletion theory -ozone couldnt be destroyed in the lower atmosphere -CFC's continually rise to higher altitudes until they are destroyed by solar radiation. - chlorine atoms produced by CFC's destroy the ozone

ODS

-ozone depleting substances -which include halons, methyl bromide, carbon tetrachloride - CFC's are the most dominate in the ozone depleting atmosphere

Dobson 1928-1958

-the dobson unit is a common unit of the measurement for the total column of ozone -if all the ozone above a certain point was brought down to 1 atmosphere at 0 Celsius. the thickness of this layer would be 3mm or about the thickness of two pennies stacked on top of each other(300 dobson units) -the thickness of a dime, or 100 dobson units(-1mm thick) is approximately the thickness of the ozone layer in antarctic -300 dobson units is the norm - developed the Dobson spectrophotometer which measures ozone

chlorine is coming from the CFC

1.CFC--> CRS in stratosphere 2.PSC form with ice crystals 3.CRS +ice crystals form CL2 4.CL2+ sunglight forms 2CL 5.CL + O3 --> o2 + clo 6.Clo + o3 --> cl + 202 7.Chlorine is considered a catalyst which forces a reaction so the chlorine in step 6 can go back to step 5 and do it again because its not being used up

PSC's role in ozone depletion

1.EFC is emitted on the surface of the earth by us. And it bumps around in the troposphere acting as a greenhouse gas 2.Stays the same in the troposphere, doesn't't change 3.CRS- chlorine reservoir species- the first step of this conversion, it can only happen in the stratosphere. 4.Only in the stratosphere is their enough energy to break this molecule

What was the Montreal Protocol

1987-Montreal Protocol- the Kyoto agreement. Only about ozone depletion, but this point there are other substances that are able to break up ozone. Things like laughing gas is an ozone depletion substance, its not a CFC- only 4 states not ratifying the agreement. Most successful in the environmental conference

what are CFC's

ChloroFluroCarbons -Non-reactive, nonflammable gases and volatile liquids -Developed in 1930s as safe alternatives to ammonia that was originally used in refrigeration and spray cans -Ubiquitous in industry -part of ODS - CFC's are a molecule - when its in the troposphere it acts as a greenhouse gas -The hairspray from the 80s is still floating in the atmosphere, it's a big fat stable molecule that wont react with anything

Process of ozone formation in stratosphere

step 1: oxygen molecules are photolyzed creating 2 oxygen atoms step 2: two oxygen atoms undergo binding collision to form ozone molecules -for every 3 O2 molcules, two 03 molecules are formed step 3: ozone molecules are broken by UV radiation breaking it into 02 and 0 molecules 90% of ozone in atmosphere occurs in the stratosphere