Page:Hunt - The climate and weather of Australia - 1913.djvu/101

Rh As the evaporation statistics might be expected to throw some light on conditions in general during drought years, the following table is appended. That the light is not particularly bright is evident, the result being confused by the fact that the rate of evaporation is dependent upon a number of factors:—

Evaporation means for the drought years are thus seen to be, in general, slightly below those for all years of record for the coastal stations, and only slightly above for Alice Springs, the one inland station given. The very low evaporation totals for Alice Springs for 1895 and 1896 were coincident with exceptionally heavy summer rains, and were what should be expected when humid conditions intervene at the time when evaporation is normally most rapid. Otherwise the results show the effect of the drier atmosphere of the drought years. At the coastal stations the lower evaporation, as well as the lower summer temperatures already noted, may be explained by assuming that during drought years the greater insolation over the interior produces greater and more frequent indraughts of moist, cool, sea air.

In the foregoing the rainfall statistics most frequently referred to were those obtained from a mean of the rainfalls at ten typical stations in the northern wheat-areas of Victoria, and a similar number from the northern areas of Southern Australia. These are—for Victoria, Swan Hill, Echuca, Yarrawonga, Warracknabeal, Charlton, Bendigo, Shepparton, Dookie, Horsham, and St. Arnaud; and for South Australia, Hawker, Quorn, Port Augusta, Wilmington, Ororoo, Petersburg, Appila, Crystal Brook, Burra, and Auburn.

The mean annual rainfall for the Victorian stations is 17.82 inches, of which 12.33 fall in the seven months April to October. The wettest year since 1880 was the year 1889, when 26 inches fell, and the driest 1902, when the total was only 10.94 inches, of which only 5.11 fell during the critical seven months. For the South Australian stations the mean annual fall