128 REPORTS ON THE STATE OP SCIENCE. — 1916. 



The assistance of those who have taken part in investigations other 

 than those herein referred to will be duly acknowledged in a future 

 report. 



The Influence of Weather Conditions upon the Amounts of 

 Nitrogen Acids in the Rainfall and Atmosphere in Aus- 

 tralia. — Report of the Committee, consisting of Professor 

 Orme Masson (Chairman), Mr. V. G. Anderson (Secre- 

 tary), and Messrs. D. Avery and H. A. Hunt. 



Cubing the period March 15, 1916, to March 31, 1916, daily samples 

 of rain-water collected at sixteen stations suitably distributed over the 

 continent of Australia have been quantitatively examined for nitric and 

 nitrous nitrogen. Altogether about 1,000 samples have been examined. 

 The results when compared with the daily weather records and isobaric 

 charts confirm the following conclusions drawn from the results of 

 experiments previously conducted by V. G. Anderson at Canterbury, 

 Victoria.* 



i. For a given type of weather the concentration of oxidised nitrogen in 

 the rainfall varies inversely as the amount of rainfall. 



ii. The total amount of oxidised nitrogen per unit area found in the 

 rainfall accompanying a storm depends upon the type of 

 weather, and is practically independent of the amount of rainfall. 



The work carried out during the past year has also shown that 



i. Antarctic storms at different stations carry down amounts of oxidised 

 nitrogen which do not differ greatly from the amounts previously 

 found at Canterbury. 



ii. Eain falling at northern stations during the prevalence of trade winds 

 contains amounts of oxidised nitrogen which are almost equal to 

 the amounts found in the rain accompanying Antarctic depres- 

 sions (rear isobars) at southern stations. This is shown to be 

 probably due to the anticyclonic origin of winds accompanying 

 both types of rain. 



iii. Passage over land modifies anticyclonic air only to a slight extent ; 

 but, if during the passage it is subjected to the influences accom- 

 panying monsoonal disturbances, comparatively large amounts 

 of oxidised nitrogen are found in the subsequent rainfall. 



iv. The highest total amounts of oxidised nitrogen are found at southern 

 and inland stations in rain-water resulting from monsoonal 

 storms following a ' heat wave. ' 



v. Eains occurring during ' divided control ' weather contain less 

 oxidised nitrogen than tropical rains, but more than Antarctic 

 rains. 



« V. G. Anderson, Report Brit. Assoc. 1914, 338 ; Quart. J. Roy. Met. Soc. 1915, 

 41, 99. 



