WATCHING WEATHER

Evening Post, Volume LXXVII, Issue 109, 10 May 1909, Page 7

WATCHING WEATHER

HOW FORECASTING IS DONE. BAROMETER THE CHIEF GUIDE. Peoplo with rheumatic joints are said to be good weather prophets, but the Government does not insist on rheumatism or gout as a qualification for a, State Meteorologist. Neither is the official observer provided with a basin of water and a frog to assist him in his prophecies. Rough and ready estimates of impending changes in the weather may be based on the antics of animals or the twinges in a toe or knee, but the prophet who gets his knowledge in that way is not usually able to pick the direction from which the disturbance will, come. Neither does the Chief Meteorologist peer from a window by day or sit up by night to see whether the moon "comes in # wet" or back to front. Wellington is not without enthusiasts who invoke the sun, moon, and stays to help them in making a hazard at the weatber for a month or moie ahead, but the Government office does not just yet reach ho far into the heavens for its information about the wind and rain that may visit this earth. BY CYCLONES AND ANTICYCLONES. When the office of the Chief Meteorologist (the Rev. D. C. Bates) was invaded this morning he wps cheerfully engaged with a low pressure cyclone, which has charged down upon New Zealand from the north-west, and had its centre at Cape Egmont at 9 o'clock. He had scares of telegrams beside him, giving the barometer readings and other conditions at the various stations throughout New Zealand, and be waa mapping out the effects likely to be produced by the depressing visitor. A cyclone is commonly understood to 'be a violent whirling wind, but in meteorology the term is applied to a low pressure movement, advancing like a great top, spinning from left to right, the direction traced by the hands of a, watch. An anti-cyclone is a high pressure movement, in which the whirl is from right to left. Thus if a cyclone has its centre in Cook Strajt the result will be westerly wind at Auckland, a northerly on the East Coast, southerly on the west, and easterly at the Bluff. An anti-cyclone, similarly centred, reverses the dispensation, giving an easterly to Auckland and a westerly to the Bluff. One has only to watch the face of a watch, to follow the range of the wind. 'The motions of the atmosphere are found to be mainly regulated by the distribution of barometrical pressure over the globe," states one of the weather text-books, and the pressures come in series, the cyclone, the anti-cyclone, the monsoonal, and the A-shaped depression, corresponding (in New Zealand) with the Y-shape of Great Britain. By watching the advance of these aerial visitors, the meteorologist gives his warnings. AN EXAMPLE. This morning's cyclone of depression was a series of low-pressure circles within circles, with 1500 miles as the total diameter. A glance at the table, printed in another column, shows that the barometer improved as the distance from Cape Egmont became greater. There is a steady rise from 29.44 from Cape Egmont to 29.80 at the Bluff, and 29.65 at Cape Maria. Places on the same curve ia\ "both Islands have, roughly, the same barometrical pressure. The line connecting such places, with the same barometrical reading, is known as an isobar, and the isobar is to the meteorologist as a crowbar to a navvy or a hair-pin to a woman. Aware that the cyclone nad its centre at Cape Egmont, and with some facts in the way of telegrams to assist time, the meteorologist is able to trace the probable course of the winds in the near future and indicate the places at which rain may be expected. Most of the North Island's bad weather is brought by cyclones and monsoonal depressions — chiefly ' cyclones — and much of the South Island's share of disagreeableness is due to westerly waves of low pressure. The 'ow-pressure cyclones are responsible for the numerous northerlies and the not infrequent southeasters that sweep Wellington. Cook Strait is 'on the boundary line of both systems, and therefore the capital may get a taste of each disturbance. The high-pressure anti-cyclones generally bring bright days, and the life of this friend is generally from seven to nine days, but it may' be rudely ousted by an enemy after a reign of only one day. NOTICE OF MOTION. P-er electric cable the low pressure waves from the west give notice of motion. When Perth announces that it has been visited by a low pressure, Hobart ■may expect a call three days later, and the Bluff may be reached in another three days. The gap between Perth and the Bluff is generally covered in five to seven days; the average is six days. However, the undesirable immigrant may be diverted, it may die away or be delayed. The cyclones manage to get a tyrannical sway for a time, but the ruling force is the anti-cyclone. For ever the high-pressure is in conflict with the low, and the high pressure wins, eventually, by (superior size and strength. It is a beautiful game of balancing, and man, taking the years through, gets the balance in his favour. GENERAL AIDS. The barometer is thus the meteorologist's chief guide; 'he looks on the glass for sign and portents. The 'Wellington ■office has a self-recording instrument, and, of course, keeps in close touch with outlying stations. Yet with all these aids, the careful meteorologist is not prone to jump at conclusions. Judgment is an important factor. The cyclones, the anti-cyclones, the low-pressure waves from the west, determine the general character of the weather ; but the wise man also studies local conditions, in conjunction with the general information given by the 'Meteorological Office. He knows the lesson to be drawn from the humidity W the air, and he sees portents in the skies — but before all and above all, is the barometer. Yet amateurs are warned lo 'be prudent when consulting the glass. "A rapid and unexpected rise of the barometer," says one authority, "is often the precursor of a coming depression, so that whenever we see a sudden rise we may expect an equally sudden fall, and must be on the look out for the slightest tendency of pressure to give \vay."

Messrs. A. L. Wilson aud Co. insert several notices in our auction columns of sales they are holding. To-morrow, at Hataitai, they will sell, ou account of Mr A'Comt, who is leaving for Sydney, the contents of his five-roomed residence. On Wednesday, at their rooms, 26, Biaudon-slreet, (hey ! will dispose of six pianos by English and j Continental makers. The same afternoon they will bubinit a large catalogue of furniture and effect c. On the following Monday, at 12.30, thov will pell 35 dairy cou.b and sundries at the faira of Mr. A 7 iclor Hughes (late Mrs. Picken's), Johns-onville. The sale is advertised as being' a clearing one. The firm insert a preliminary notice of an auction sale they arc holding at 6 , Pitt-street. Berhamnore, on behalf of Mi. J. Barlow. For Children's Hacking Cough at night, Woods' Great Peppermint Cure. Xi 6d I ftnd gs 6d.— Advt,