THE LAWS OF STORMS.

Globe, Volume XXI, Issue 1668, 25 June 1879, Page 3

THE LAWS OF STORMS.

Mr Scott, of the Meteorological office, has lectured at the London Institution on storms, the announced title of the lecture being " The Birth, Life, and Death of a Storm." Of the birth—the origin—of storms it was said we still know but little with certainty. Four theories were mentioned as having been put forward to account for them. 1. By some authorities the formation and subsequent progress of storms is attributed to the condensation of moisture, but it did not seem to be borne in mind by them that many of the very heaviest rains do not give rise to the most soriouß cyclonic disturbances at all ; as for example, the heavy rainfall of the 10th and 11th of April, 1878, when 4£ inches fell at Haverstock Hill. 2. The second theory is a mechanical one, strongly urged by Mr Meldrum, which is that every cyclone is generated in tho intervening Bpace between two oppositely flowing ourrents of air. Messrs Blanford and Elliott, however, studying the phenomena in the Bay of Bengal, fail to see any grounds for this. Again, this theory does not assign a vera causa sufficient to give the first impetus to the barometric fall and the rotatory movement of the air. 3. A third theory is that the storms originate in the upper regions of the atmosphere and extend downwards; but among other obioctions to this there was mentioned the war. . --pout seen on the Lake of Geneva on che 2nd of January, where the winds known locally as the Fohn and the Bisc raised a waterspout which did not descend from the clouds. 4. The fourth theory mentioned was that of the late Mr Thomas Belt, who sought the first cause in the heat of the sun. The heat rays pass through the atmosphere without warming the upper strata, and bo Mr Belt supposed that over a sandy soil a mass of air close to tho ground might rise in temperature much higher than the superincumbent layers of the atmosphere. The lower strata would therefore become lighter, and a condition of unstable equilibrium would arise. The lecturer went on to say that as all these theories had something in their favor it was probable that the production of a cyclonic disturbance may bo due to more than one agency. The history of tho storms when they have onco started on their course is more certainly known. It ia a mistake to assert that all Btorms are distinctly connected with cyclonic disturbances. Defining the term " cyclone " in its very widest acceptation, as indicating a region of diminished pressure, round and upon which tho air is moving along paths which aro moro : symmetrical all round the centre the more perfect ia the circular form of the systom, it is at once seen that not every cyclone is accompanied by a storm. Tho fact is that tho direction and force of the wind aro regulated by the difference of barometrical pressure over a given distance, and not in any way by tho actual height of the barometer at the Btalion at which the storm is felt, or by the distance of that station from the point where tho barometric reading for tho time being is the lowest. This explanation of wind modon is almost the only new principle which has been recognised in meteorological science during tho present generation. It is usually formulated, " Stand with your back to tho wind, and the barometer will be lower on your left hand than on your right." The final result of all the inquiries into the question is that on the mean of all winds tho angle between their direction and tangent to the ieobar at the place ia about twenty degrees. The old idea was that the air blew round and round tho central calm in circles, so that any sailor caught in ono of thoao etorma could at onco know that the centre bore eight points from the direction of the wind on the port side in tho northern and tho starboard side in the southern hemisphere. Modern meteorologists, however, accept the spirally incurving movement as the most probable behaviour of tho wind. This makes it probable that, tho true position would be at least two or three points ahead of that indicated by the old rule. This is a subject which requires tho iuo6t careful study in order to see whether or not the time-honored rules for handling ships in rotating storms require modification. Turning to the consideration of the phenomena of cyclonic disturbance as it passes over us, it was amongst other things mentioned that very little is known of tho ' rate at which they pass. Some are known to

go at the rate of 60 miles an hour. Tho Weßt Indian hurricanes are slower, and there does not seem to be any connection between the force of a storm and the rate at which it travels. The practical value of the warnings sent to us during tho last two years by the "Now York Herald" was then referred to. By practical value the lecturer explained that he meant the value to fishermen and coasting sailors. It is evident that a warning which is not fulfilled locally may mean a loss of some hundreds of pounds to a fishing fleet kept in by that warning. The same remark applies to our own warnings, but these American warnings are very general in their scope. They speak sometimes of a storm as likely to reach tho British Isles, France, and Norway, and it is an unheard-of thing that a gale should prevail simultaneously over such a wide area. It is one thing for a scientific man to say that he can recognise the presenoe of a predicted storm on our coast and another thing to say that a storm which begins two days after or two days before the time predicted is really the very disturbance. which left the American: coast. The tables constructed show that in 1877 there were 42£ per cent, successful predictions against 57£ failures ; and in 1878 45 per cent, successes against 55 failures. This is taking the results in their moat favorable aspect. The lecturer concluded by saying that though at present these warnings had not been of great practical use we need not despair. We must attend to the subject from its scientific side, and discuss results in a dispassionate spirit.