92 The N.Z. Journal of Science anl> Technology. [Mar. 
The actual direction of the wind at each reporting station is denoted by 
an arrow, and a glance will show how variable it is in the central area, which 
is about Cook Strait. At Wellington the wind is north-east, while at 
Farewell Spit it is south-west. North of the path of the centre the tendency 
is all for easterly winds, while in the south the predominating direction is 
westerly. Along the east coast of the North Island—that is, in front of 
the central isobar of 30-3 in.—southerlies prevail. 
As the whole system moves forward to the east the winds over the 
North Island will “ back ”* (or change in an opposite direction to the motion 
of the pointers of a clock) — i.e., from easterly to northerly ; while in the 
South they will “ veer " (or change in the same direction to the motion of the 
pointers of a clock)— i.e., from west to northerly. 
Such an anticyclone, in summer, would account for high temperature 
in the daytime, and the nights would be cool ; frosts might even occur 
at some of the high inland places. 
Anticyclone centred North of New Zealand. 
Fig. 2 is a case where an anticyclone is centred in more northern latitudes, 
and pressure shows a gradual decrease southwards, in which quarter is the 
steepest baric gradient. The trend of the isobars is approximately due 
west and east over New Zealand, and favourable to strong westerly winds, 
especially over the South Island and in Cook Strait. With this distribution 
of pressure showery weather is experienced on the western coast, extending 
as far north as Cape Egmont at least, and also often passing through Cook 
Strait. 
This is a type of pressure which is rather prevalent in the spring, and to 
which the continued dry weather so often experienced at this season of the 
year in the eastern provinces is accountable. 
The normal track of our anticyclones varies according to the seasons, 
being located in higher latitudes in the summer than in the winter. In the 
spring months the position, then, would be midway, as shown in fig. 2, and 
this would therefore appear to be the critical period for the east coast dis¬ 
tricts, especially as precipitation then is more urgently required for growing 
crops. 
Anticyclone centred South of New Zealand. 
Fig. 3, the chart of 23rd June, 1913, proves an exception to the above 
rule, for instead of being in lower latitudes in this case the “ high ” centre 
is considerably to the south of the Dominion, while relatively low pressure 
exists to the northward. 
This synoptic chart, as will be readily seen, is the reverse of the preceding 
one (fig. 2) ; as the latter was representative of westerly type of weather, 
fig. 3 may be taken as a high-pressure system in which easterly and south¬ 
easterly winds are dominant. It was responsible for a spell of intensely cold 
weather in the east-coast districts, with heavy passing showers, particularly 
northward of Kaikoura. In the western districts clear skies ruled, with 
frosty nights. 
* The terms “veering” and “backing” were originally used to express the change 
of wind-direction with and against the sun’s apparent movement. The International 
Meteorological Committee, however, in 1905, adopted the following resolution : 
“ Meteorologists in either hemisphere are requested to denote by the word ‘ backing ’ 
a change of wind-direction at the place of observation (or on board ship) in the direction 
west-south-east-north (counter-clockwise) — irrespective of accompanying changes of 
weather—and to use the word ‘ veering ’ to denote a change in the opposite direction— 
west-north-east-south (clockwise).” (Rep. Internal. Met. Conf. at Innsbruck, Sept., 1905, 
p. 41, item 47.) In the Southern Hemisphere the terms are, therefore, now used in the 
reverse sense to that in which they were original]y employed. 
