Votes and proceedings of the General Assembly of the state of New-Jersey . re. Attemptswere made to find the upward extent of the absorption bymaking observations from mountain tops, but theseobservations still showed the cutoff in the solar spectrum,making it clear that the ozonosphere must besituated high in the atmosphere. In 1917 observations of the rising and setting Sun wereused to provide an indication of the distribution of ozone inthe atmosphere. Because of the changes in the absorptionspectrum which occur as the Sun is observed throughsuccessively longer columns of air as it sets (or
Votes and proceedings of the General Assembly of the state of New-Jersey . re. Attemptswere made to find the upward extent of the absorption bymaking observations from mountain tops, but theseobservations still showed the cutoff in the solar spectrum,making it clear that the ozonosphere must besituated high in the atmosphere. In 1917 observations of the rising and setting Sun wereused to provide an indication of the distribution of ozone inthe atmosphere. Because of the changes in the absorptionspectrum which occur as the Sun is observed throughsuccessively longer columns of air as it sets (or shorter asit rises) it was possible 60 years ago to determine that ozoneconcentrates in a layer between 40 and 60 km above sealevel. More modern observations, using the same technique,give better limits of 10 to 50 km, with concentration maxi- Figure I. The dashed line shows the energy output of the Sun fora surface temperature of 6000 K, the solid line shows theobserved spectrum at ground level, with an abrupt cut-off at2°f) nm ranged by absorption in the ozone laypr. mum at an altitude of about 25 km This pattern has beenconfirmed by direct measurements from balloon-borneinstruments and from spectra obtained using rockets andsatellites. The layered structure of the Earths atmosphere and theplace of the ozone layer in that structure can be seen bestby considering the variation of temperature with altitude(Figure 2). The atmosphere is kept warm by the Sun. Somesolar radiation is reflected away into space at the top ofthe atmosphere, ultraviolet and infrared frequencies areabsorbed in the upper regions, but by far the bulk of thisincident energy penetrates to the ground. The warm ground provides heat to the atmosphereimmediately above it, partly by conduction but mostly byradiation at infrared frequencies, which are stronglyabsorbed by atmospheric water vapour and carbon dioxideIn turn, the lower atmosphere re-radiates part of thisenergy, some returning to the surface for anot
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