TRANSACTIONS OF THE SECTIONS. 35 



This Is no ddubt owing to the change taking place in the one class of storms in the 

 lower strata, while it is taking place in the upper regions in the other. It is also a 

 characteristic of these westerly gales, that the south-west wind, at the surface of the 

 earth in its first stages, crosses the whole island in one broad stream, beginning to 

 blow almost simultaneously in Cornwall and the north of Scotland. The oscillations 

 of the barometer also often correspond as to time, but vary as to amount. It is 

 seldom that much rain falls in the eastern counties under these conditions of atmo- 

 spheric currents ; but it falls copiously in the western, where the lower current is 

 driven up the high grounds, and probably projected into the colder current above. 

 There is no doubt that the upper current from the north-west not only produces 

 cloud, which, so far as our observations extend, is peculiar in shape and form to this 

 course of winds, but it actually acts in many instances as a condenser in throwing 

 down considerable quantities of rain. A good instance of this occurred on the 27th 

 of August, 1850 : early on that morning the wind in Fifeshire was north-west and 

 very cold ; it fell to a calm below, and a warm moist south-west wind sprang up, 

 and gradually veered rocnd to south-east, east, north-east, and at last to north-wesfr 

 at night. This is by no means a common occurrence, as it usually goes the other 

 way: '71 inch of rain fell in Fife, and ri inch at Whitehaven, in Cumberland, 

 where it also rained the whole day. When the clouds began to clear away towards 

 night, I observed the cirrostratus lying like vanes pointing north-west to south-east, 

 which was gradually evaporated by the wind when it got round to the same direction. 

 In the more violent storms of wind the upper strata appear to be excessively cold, 

 and the great alterations of temperature which occur are closely connected with this 

 circumstance. The weather was remarkably fine and warm over Britain about the 

 15th of August : it was the finest day of summer in Fifeshire ; the maximum shade 

 temperature rose to 80°. The barometer fell very rapidly on the 18th and IQth at 

 Dunino, with a very heavy gale of wind. A repetition of the gale and fall of the 

 barometer took place on the 25th. In both cases the south-west wind was blowing 

 over the whole island, from Inverness to Cornwall, and when the storm set in an 

 upper north-west current prevailed. The temperature of the higher strata seems to 

 have been intensely cold on the 20th, 21st, 22nd and 23rd; hail-showers were more 

 or less common over the whole island. The cumuli were very low, and the sky of 

 that deep and transparent azure which only occurs in summer, when the sun heats 

 the lower strata of the atmosphere. In Forfarshire and Banffshire devastating storms 

 of thunder, with hail, occurred ; the Grampian Mountains were covered with snow 

 in many places. 



It is worthy of remark, that on the 18th and IQth of August, when the barometrical 

 pressure was very light in Fifeshire, the north of France and Belgium were visited 

 with great falls of rain, which flooded all the low countries. We have avoided in this 

 short sketch all reference to theory, but on another occasion we may enter upon this 

 ground. In the meantime we close this paper by expressing our opinion that little 

 progress will be made in developing the law of storms until the directions of the wind 

 in the higher and lower strata of the atmosphere are more generally observed and 

 carefully registered. 



On some of the Appearances which are peculiar to Sunbeams. 

 By Henry Twining. 



In this communication, the author noticed the condition of the cloud and the state 

 of the atmosphere which usually give rise to the appearance of luminous beams. He 

 observed that the luminous rays are formed chiefly in the lower regions of the atmo- 

 sphere, but that they are nevertheless seen at times at very great elevations, since 

 they occur as much as 20 minutes after sunset. 



He called attention to the peculiar perspective eflects which are connected with 

 the appearance of luminous rays, as they occasionally seem to extend in the most 

 opposite directions, although their real direction is invariably the same. Referring 

 to a belt of exceedingly dark shadow which surrounds the luminous margin of clouds. 

 he stated that it differs essentially from the usual appearance of solar radiation, and 

 proposed a hypothetical explanation of this peculiar effect. 



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