It may be unfair, but when somebunny volunteers as a pinata, who is Eli not to go to Bad Bunny. Peter L. Ward has been spreading nonsense like fertilizer, most recently at Walter Hannah's blog, and neither Ankh nor AT were kind enough to clue Eli in on the fun, so the Rabett will have to simply cut and snip. To say that Ward is a few drops short of a clue, would be generous. OTOH, Eli is rather better prepared to deal with the nonsense than most because he has studied and worked in the areas of atomic and molecular physics, physical chemistry, chemical physics, spectroscopy and kinetics so he can recognize climate baff on sight.
It is such a rich display, that were it a buffet the Bunny would have to check in for lap band surgery. The choice is difficult, but one must start with something Ward gets wrong (and there is little he gets right), perhaps here
Heating of the stratosphere is done primarily by O2 absorbing UV-C and being dissociated. Many other gas molecules are dissociated in the stratosphere including CO2, but their concentrations are very low. We have observed for a long time that the top of the stratosphere averages about 70oC warmer than the tropopause. These facts are not included in typical energy balance efforts by Trenberth and others. Why not?Let Eli start at the top
Heating of the stratosphere is done primarily by O2 absorbing UV-C and being dissociated.Well, as a matter of fact not. Heating of the stratosphere is initiated by dissociation of O2 (Step 1) but the heating is done primarily by absorption of light and dissociation of ozone (Step 2) followed by regeneration of the ozone (Step 3). The chain is terminated in Step 4. The name for this is the Chapman cycle
(1) O2 + hv (< 200 nm) --> O + O
(2) O + O2 + M --> O3 + M
(3) O3 + hv (306 < λ < 200 nm) -- > O + O2
(4) O + O3 -> O2 + O2
The figure is from Chapter 5 of the Stratospheric Ozone Textbook linked at the top of the sidebar and a good place to look for details. The key to the good Dr. Ward's confusion is both spectroscopic and kinetic as well as involving the structure of the atmosphere and the solar flux. The dissociation of oxygen requires light below 200 nm (technically below 243, but the absorption there is very low in the so called Herzberg Band, and does not really pick up until 195 nm or so where the Schumann Runge band kicks in).
Ozone, OTOP, has a bell shaped absorption
between 306 and 200 nm. One also has to understand that a) there are orders of magnitude more oxygen (O2) than ozone (O3) at all levels of the stratosphere, and orders of magnitude more ozone than oxygen atoms.
2 in the atmosphere the UV radiation below 200 nm falls to zero quickly at the top of the stratosphere. A spectrum of the UV actinic flux above the atmosphere can be found at Penn State. The UV between 200 and 300 nm is absorbed by the ozone, which is more concentrated between 25 and 35 km as can be seen in the figure to the right by comparing the fall off with the ozone spectrum above.
Putting this all together, the rate at which O atoms are produced in the photolysis of Step 1, is slow, and primarily occurs at the top of the atmosphere, where all of the radiation that can dissociate O2 is absorbed. The O atoms rapidly react with O2 (a matter of seconds) to form ozone, O3. If there was no third body (M standing for nitrogen or another oxygen molecule) then the O3 would have energy above the dissociation limit and simply fall apart again. However even in the upper stratosphere there are enough oxygen or nitrogen molecules to make this possible. The chain steps 2 and 3 result in a heating of the stratosphere. Step 4, the termination, is really slow, but there are additional reactions involving Cl, Br and water that deplete the ozone to an observed level. Still odd oxygen, O and O3 persists long enough to move down through the stratosphere to 30 km or so, the ozone layer. A detailed discussion of the kinetics can be found at Harvard and discussion of the solar spectrum at various layers in the atmosphere, aka the actinic flux at Penn State.
The reason why ozone absorption rather than oxygen molecule absorption is responsible for most of the stratospheric heating is simple
Step 1, the photodissociation of oxygen molecules is very slow because the amount of UV radiation below 200 nm is low. Thus the number of oxygen molecules photodissociated per second is low and the number of O atoms produced per second is low.
Steps 2 and 3 in the Chapman cycle, absorption of a UV photon by ozone followed by dissociation and the cyclical regeneration of the ozone molecule by reaction with oxygen molecules and a third body are repeated myriad times before termination.
Oxygen molecular photodissociation occurs only once
Many other gas molecules are dissociated in the stratosphere including CO2Nope, CO2 won't be dissociated in the stratosphere, because it doesn't start absorbing until 180 nm or so. Absorption by oxygen higher up will stop any of the < 180 nm light from reaching CO2 in the stratosphere.
And finally from Peter L. Ward we have
We have observed for a long time that the top of the stratosphere averages about 70oC warmer than the tropopause. These facts are not included in typical energy balance efforts by Trenberth and others. Why not?