William Napier Shaw

“ SQUALL, the name given to any sudden increase of wind to gale force. Generally speaking a squall is understood to be of short duration, but the word " gust " would be used to indicate an increase of wind force of more transient character than a squall. Gusts may succeed one another several times within the compass of a minute. A squall may comprise a succession of gusts, with intervening partial lulls, and would last with varying intensity for some minutes at least. ”

“ The air which remains after the passage of a line squall is, how- ever, distinctly colder, of an entirely different kind from that which it replaces and, in those cases which have been investigated, can be traced back to a different point of the compass. ”

“ As examples of the cutting of the belt for different latitudes we may put side by side the recorder as used in temperate latitudes (fig. 1) and the special form designed in the Meteorological Office, London, for use on the National Antarctic Expedition, 1901-1904 (fig. 2) . A belt cut for a particular latitude is serviceable for some 10° on either side of that latitude if the cards are not trimmed too must always be closely to the cutting of the belt. ”

“ The line of advance of a line squall is generally from some point between south and north on the western side, the change of wind being from a warm southerly or westerly wind to a colder westerly or northerly one. ”

“ The excursions of the sun to the north and south of the equator are limited by the tropical circles, and the solar record on the hemispherical bowl will be confined within a belt 23° 27′ north and south of the plane through the centre parallel to the equator or perpendicular to the polar axis. ”

“ The pressure changes are continuous in the old layer and in the new layer, but discontinuous with varying degrees of discontinuity along the line of junction, where instability of the upper air may be set up. ”

“ They comprise a sudden increase of wind with a veer of direction of 45° to 90 , a sudden rise of pressure known in France as the crochet d'orage, and in Germany as the Gewitter Nase, a pronounced and permanent fall of temperature, and a shower of rain, hail or snow. While these various phenomena are indicated all along the advancing line their intensity may be very different at different points along it. The squall often exhibits greater violence in the middle portion, and it becomes more intense as the whole line advances. ”

“ Moreover, the smallness of vertical dimensions in the atmosphere as compared with the horizontal dimensions makes it difficult to allow that there is really room for an effective vortex with a horizontal axis. ”

“ In North America, values exceed 3250 hours per annum in the New Mexico region. For other parts of the world the information available is not sufficiently extensive for the construction of charts. Eject upon Sunshine Records of the Smoke of Great Cities.—Much discussion has taken place from time to time as to whether the climate of a locality can be altered by artificial means. ”

“ As a climatological factor of the locality the shadow cast by the surrounding hills is of importance, it is part of the difference between the fertility of the southern and northern slopes of hill country. ”

“ Fig. 6 shows the average duration of bright sunshine for each hour of the day for each month at Valencia. The expectation of sunshine is greatest at I p.m. and 2 p.m. in May, while there is a well-marked secondary maximum in September.
ExPOS14f¢.-We now consider what the daily sunshine record for; particular station means. An ideal exposure has an uninterrupted view of those parts of the
horizon in which the sun rises or sets; Further, fig. 9 represents the average weekly distribution of sunshine in different sections of the British Isles according to the average of twenty-five years. ”

“ In these circumstances it 55° 237 265 276 363 418 494 510 511 456 376 319 245 218 becomes a question whether the amount 56° 232 263 273 362 420 499 516 516 459 376 316 239 2 1 1 of sunshine recorded should be referred 57° 226 260 270 362 423 504 524 523 463 377 314 236 205 to the maximum possible for an un- 58° 219 257 267 361 426 510 532 530 467 378 312 232 197 interrupted horizon or the maximum 59° 211 253 263 361 429 517 541 538 471 379- 309 225 187 possible for the particular exposure. The answer to the question really depends upon the purpose for which the information is wanted. ”