Meeson. — The Rainfall of New Zealand. 555 



Pabt II. Eain-bringing Winds and Cyclonic Tracks. 



To understand the rainfall of a country and its causes we 

 must inquire what are the winds wdiich, in the various places 

 where observatories have been made, bring the rain. Existing 

 differences of climate mainly have their origin in prevailing 

 winds, and the science of meteorology is for the most part 

 comprised in the law of storms, since that law deals chiefly 

 with wind and rain. To be more precise, rainfall is deter- 

 mined by prevailing winds considered in relation to the re- 

 gions from wdiich they come and the physical configuration 

 and temperature of the colintry blown over ; the maximum 

 occurring where winds, after traversing the ocean, come 

 against mountain-chains in their passage to colder places, and 

 the minimum where the prevalent winds come over mountain- 

 ridges to w^armer lands. — (Loomis.) 



Now, in our attempts to get at the rain-bringing winds 

 of New Zealand, the want of statistics is again painfully evi- 

 dent. The full particulars which w^o need for the investiga- 

 tion are only given for the three first-class meteorological 

 stations. It is so far fortunate that these places are situate 

 as widely apart in the colony as they well could be — Auckland 

 in the north, Wellington in the centre, and Dunedin in the 

 south. They are, moreover, places more exposed to western 

 weather, as it happens, and therefore more representative of 

 the climate of the colony than many places on the east coast 

 which could have been chosen. For these places the rainfall 

 of each day in the 3'ear is recorded, with the direction of the 

 wind, so we can construct for them what are called " wind- 

 roses." It is to be regretted, however, that the tables do not 

 seem to be compiled precisely on a uniform system. Unless 

 they are, the figures are misleading. For example, in the 

 year 1880 there was not recorded a single calm day in Auck- 

 land, only two in Wellington, but 115 in Dunedin ! On 

 examining the figures carefully we find an explanation of this 

 remarkable testimony to the tranquillity of the Dunedin 

 climate. In Auckland, if the air moves only at an average of 

 two miles an hour, the direction of the wind is given, and no 

 calm is recorded, though, according to the Beaufort scale, the 

 average velocity of wind in a calm is taken at as much as 

 three miles an hour. In Wellington, similarly, no calm is re- 

 tm-ned, even when the total motion of the air during the day 

 is only ten miles ; but yet, as it would seem, inconsistently 

 enough, on the 29th .June and on the 4th August, on each of 

 which days the wind travelled fifty miles, calm is recorded. 

 In Dunedin the meaning of " calm" is even more incompre- 

 hensible, for under the heading " Direction of Wind" we see 

 " calm " recorded even when the wind travelled as much as. 



