CYCLES IN WEATHER

New Zealand Herald, Volume LXXVI, Issue 23274, 17 February 1939, Page 20

CYCLES IN WEATHER

[(ELATION TO SUN SPOTS APPLICATION TO FARMING SOUTH AUSTRALIAN DISCOVERY

BY OUiniRK

It has long been held, but without any very conclusive proof, that the weather in any particular locality is repeated in 11-year cycles. These cycles, again, are said to be associated with the periods of maximum development of sunspots, which, again, occur at 11-year intervals.

Recently an Australian research" officer, Mr. A. E. Cornish, of the Waiti Agricultural Research Institute, South Australia, has made a detailed study of the rainfall records of Adelaide, which are perhaps unique in Australia and New Zealand in that they have now been kept uninterruptedly for 100 years. After tabulating and examining a vast amount of statistical material, Mr. Cornish has demonstrated the existence of a pulsation, or cycle, in the incidence of the winter rains. This pulsation, he says, has approximately a period of 22 years, just double the period between maximum sunspots. He has demonstrated from these statistics that over a period of 11 years tho winter rains become progressively earlier and then through a similar period fall back to their original position in the calendar. "About 1845," ho says, "the winter rains were late, arriving at the end of May, but from that year onward the seasons became progressively earlier until 1856. At this time the seasonal break came toward the end of April. During the next 11 years the seasons gradually became later, until 1867, when they were again breaking at tho end of May. Since 1867 tho whole cycle has been repeated several times, the oscillation carrying on independently of the quantity of annual rainfall recorded." The results of these studies have many applications, the most important of which, perhaps, is the guidance which they can give farmers and graziers as to weather they are likely to experience in the forthcoming year, or period of years. With reliable knowledge of this sort, it is possible for them to make provision against bad seasons, and to take advantage of those which are favourable.