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Discussion of memoirs. On a theory of upper‐atmospheric ozone
Author(s) -
Chapman S.
Publication year - 1932
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49705824304
Subject(s) - ozone , atmospheric sciences , dissociation (chemistry) , radiation , ozone layer , environmental science , chemistry , meteorology , photochemistry , physics , nuclear physics
The main part of the paper consists of a discussion of the daily and annual variations of the ozone content of the atmosphere in any latitude up to about 50°. The ozone is treated as if it were uniformly spread through a layer of air 10 km. thick, having the same density as the air at the level of maximum ozone density. Convection and diffusion of ozone are neglected. The thermal decomposition of ozone (2O 5 = 3O 2 ) is discussed, and estimated to be negligible, except possibly in connection with an eleven‐year (sunspot) variation of ozone. The ozone is supposed formed and decomposed in the 10 km. layer; formation is attributed ultimately to dissociation of O 2 by ultra‐violet radiation (1300‐1800Å); the ozone is supposed decomposed by longer‐wave radiation (2300‐2900Å); the intensities of radiation in these bands are supposed to be not greatly different from those that would occur in the spectrum of a black body at 6000°; the photo‐electric efficiency of the radiations is supposed not to be very low. Then, day by day, the dissociation of ozone would seriously reduce its amount, were it not compensated by rapid reformation (O + O 2 = O 3 ). The fact that the daily variation of ozone is inconspicuous is used to estimate a lower limit for the rate of this recombination. In so far as dissociation (O 3 = O + O 2 ) and re‐formation (O + O 2 = O 3 ) balance one another, they have no ultimate effect on the amount of ozone; but new O atoms are formed by dissociation of O 2 , and this tends to increase the amount of ozone. This rate of increase is supposed held in check by reactions which cause the reversion of some of the O (formed from O 2 and O 3 ) and O 3 to O 2 , by the reactions 2O = O 2 , O+O 3 = 2O 2 . These reactions occur mainly by day; most of the O atoms then present have been formed from 0 3 . It is shown that the varying rates of these reactions can explain the observed annual variation of ozone, provided that the coefficients of reaction have suitable values.