1919.] Pemberton.—Weather Forecasting in New Zealand. 91 
Westerly Areas of Low Pressure . 
Farther north than the latitudes in possession of the cyclonic systems 
we come to the region of anticyclones. The latter move somewhat irregu¬ 
larly from west to east, accompanied on their southern extremities by the 
before-mentioned Antarctic cyclones. Between adjacent anticyclones the 
northern portions of these cyclones tend to wedge themselves, with the 
result that in each case a j \-shaped depression is formed. This is the 
commonest of all the “ lows ” which pass over the Dominion, and is 
frequently referred to in the weather reports as a westerly area of low 
pressure , particularly when the isobars assume a wider sweep than in an 
actual Antarctic f\. 
Tyrical Examples. 
The above descriptions distinguish briefly the chief weather controls, 
and show the principles on which forecasts are based. It will make the 
matter more explicit if the statements made are now illustrated by means of 
examples of atmospheric systems that have actually existed. 
A Typical Anticyclone. 
Fig. 1 shows a typical anticyclone or high-pressure system which over¬ 
spread the Dominion on the 13th August, 1912. Its centre, or inner isobar, 
circled the whole extent of New Zealand, and when such is the case fine and 
clear weather results, and in winter, late autumn, and early spring sharp 
frosts occur in places subject to them. The large arrows denote the approxi¬ 
mate direction of the wind in relation to the isobaric trend. 
Fig. 1 . — Weather chart, 13th August, 1912. Typical anticyclone, or ' l high.” 
