[Proc. Rot. Soc. Victoria 33 fN.S.), 1921.] 



Art. IX. — Possibilities of Modifying Climate by Human 

 Agency, ivith Special Application to South- Eastern Australia, 



By E. T. QUAYLE, B.A. 



(Supervising- Meteorologist, Commonwealth Meteorological Service). 



[Read 9th September, 1920] 



Many attempts have been made by more or less violent means 

 to compel the atmosphere over dry areas to part with its moisture, 

 .and all have been futile. In the following paper, evidence is 

 brought to show that methods more in accord with Nature's re- 

 quirements are actually successful. 



The proofs, or evidences, are mainly dependent upon the rain- 

 fall data controlled by the Commonwealth Meteorological Ser- 

 vice, and deal only with the Southern parts of Australia. 



The most important climatic conditions in any one latitude are 

 in general dependent upon the distribution of land and water 

 areas. As this is mainly so on account of the difference in eva- 

 poration from them, we may substitute for water areas the term 

 " evaporation areas." It is possible to conceive of sufficient eva- 

 poration for abundant rains from areas remote from the ocean, 

 though, of course, under the planetary condition of atmospheric 

 circulation, it may be impossible to make any inland district ab- 

 solutely self-contained as regards its water vapour. Evaporation 

 results have shown that a land surface, if well grassed, may give 

 rise to greater evaporation than a water surface. This is also 

 probably true of forest coverings in the ordinarily moist climatic 

 regions, though not, I think, of forests in countries subject to 

 prolonged droughts, times of very low humidity, and high tem- 

 peratures, such as is the case in inland Australia. Our forest 

 vegetation has to become specially adapted to meet drought con- 

 tingencies. Taking, for example, the forest covering of our 

 Mallee districts, consisting mainly of various species of dwarf 

 Eucalypts, one cannot fail to be struck by its unmoved appear- 

 ance after the worst of droughts, even the 18 months' drought 

 of 1913-14-15, and the serious summer drought of 1911-12, leav- 

 ing the trees as fresh looking as ever. Of course, there was prob- 

 ably not the usual amount of growth, but the trees had not lost 

 much of their vitality. 



Quite apart from the results of experiment in measuring plant 

 Iranspiration, it would thus appear obvious that these trees 



9a 



