RECURRENCE OF WEATHER

Timaru Herald, Volume CLVI, Issue 23083, 23 December 1944, Page 7

RECURRENCE OF WEATHER

Long-Range Tests May Tell In these days, when nine out of every 10 country people watch the sky day after day for the smallest indication of what the weather is going to be, a correspondent of the Melbourne “Argus” recalls the many old-fashion-ed ways of foretelling the weather. “Grandpa’s bunion is aching again,” or “The old wound’s been giving me rats for days.” “The curlews wouldn’t let me sleep a wink last night, and the sugar ants are busy to-day.” Then it might be that the cat washed its ears this morning, or that the sheep have been kicking a lot while being shorn. Of course, there was the new moon which came in on its back, full of rain, according to some; and to others a rainless moon because it was holding its rain and would not let it out. Undoubtedly all the votaries of “my lady moon” will gnaw their flingernails to the quick at my blasphemy when I defy any of them to predict the weather infallibly from the new moon. To the student of the sun’s effect on our atmosphere, however, “I dips me lid.” Long-range prediction of the weather is based on data gathered by students all over the world, and co-ordinated by research workers who study the radiation of the sun’s energy and its effect on the weather conditions of our planet. Observatories In Desert Foremost among these is Dr. Charles Abbot, of the Smithsonian Institute at Washington, U.S.A. He has observatories at Mt. Saint Katherine in Egypt, at Montezuma in Chile, and on Table Mountain in California. Each of these is in a desert area, so that observations made are less likely to variations due to prevailing local weather. The daily observations and calculations made at these stations and co-ordinated and recorded in Washington show accurately the day-to-day variations in solar radiation. Comparing these with the resulting weather should make it possible to predict fairly accurately the weather associated with different solar radiations. However, this science is in its infancy, and years of experience and recording will be necessary before any degree of accuracy is attained. To understand the basis of this forecasting one must realise that solar radiation is not constant, and that the output; of energy varies as much as three per cent, up and down. This may be influenced to some extent by the fact that the sun turns on its axis about once in every four weeks, and to the sun spots, which extend up to 20 million square miles in area. One can better realise the extent of these spots when one recalls that the area of Australia is only three million square miles. In size the earth compared with the sun is like a small marble alongside a sphere three feet in diameter. Contrary to the usually accepted idea, sun spots do not decrease the radiation of energy, but rather intensify 'it, in. much the same way as poking a fire causes it to emit more heat. Solar Radiation Sun spots wax and wane fairly regularly over a period of slightly more than 11 years, and were at their minimum in spring, 1933, so they are again approaching their minimum. Thus solar radiation has a rhythmical pulse of somewhat more than 11 years, and its effects recur on the atmosphere of the earth in periods of multiples of these periods between pulsations. The effect of this rhythm is varied considerably by local climate, the seasons, and the elliptical course of the earth around the sun. In 1920 H. H. Clayton, of the Argentine Weather Bureau, reported in the “Smithsonian” that “after much research he was convinced that all existing abnormal changes, which we call weather, have their origins chiefly, if not entirely, in the variations of solar radiation.” He collaborated with Dr. Abbot, and they discovered that weather is repeated evety 23 years, and so 23 years is now accepted as the “mas-ter-key” for forecasting the weather of the future. To verify this theory of a 23-year cycle, Dr. Abbot examined the width of the annual growth rings in several of the 1000-year-old sequoia trees in California, and found that the width of these rings conformed to the cycle. More observations were made of the silt deposits in lake areas. Here again he found that the annual deposits varied, conforming to the same cycle. He also studied the flood records of the Nile River, which date back thousands of years, and is satisfied that they bear out his theory. However, it is too much to hope that all we have to do is look back 23 years and we shall find a prediction of what 1945 will bring. Much more time and labour, more observations, and local records will be necessary before we can confidently contradict grandpa when his bunion aches.