Is it not a fact that the temperature and barometric pressure are exposed to sudden and marked changes? Have you known the temperature to fall, say, as much as 22° in 15 minutes?
The temperature sometimes changes rapidly in the summer, coming with a change from a hot wind to a cold southerly, although the instances are rare. Once in 30 years I have known such a change to amount to 22° in 15 minutes. Under ordinary circumstances the change in temperature from hot to cold wind takes several hours to amount to 20°. The fluctuations of barometric pressure are moderate, seldom amounting to half an inch in a day, or an inch in a week. In England, on the other hand, the pressure sometimes varies quickly to the extent of two inches.
Yes; the temperature much more so than the barometric pressure; it has fallen from a high temperature to 20 and even 30 degrees sometimes in as many minutes, when a hot north wind has suddenly changed to a cold southerly one. But such sudden and great changes occur very seldom, and then only in the hot summer months, and are known as "the change." On several occasions in the last 30 years it has fallen from 105° in the shade to 70° and G5° in the shade in less than an hour.
Yes, in the summer; but, especially as regards temperature, rarely in the winter. One notable example occurred on February 9th, 1887, when during a heavy thunder-storm the temperature fell 25° in 10 or 15 minutes, followed by a rising temperature. In other instances the fall of temperature has been almost equally rapid. From this it will be seen that we are subject to large and quick falls of temperature following extreme heat. The approach of hot weather is usually gradual, and the fall abrupt. The barometer has been known to show a rise of 6/10 of an inch in 24 hours; this, however, is exceptional.
There is no record of a fall of as much as 22° in 15 minutes. But, on the other hand, a rise of 30° in three hours is a common feature over the Darling Downs after sunrise. Owing to the diathermancy of the atmosphere already referred to, it is a fact, nevertheless, that in the "continental" or inland districts of Southern Queensland the temperature in winter is subject to sudden and marked changes. Barometric pressure, owing to the comparatively low latitude, is not exposed to sudden and marked changes, except during hurricane conditions, which usually affect the central coast-line in February and March.
As a corollary to the preceding, would you say that the climate is marked by great variability?
No; just the opposite. Indeed, as regards Sydney itself, there are few cities in which so much uniformity of temperature and slow changes are to be found. The cause of any great change is the hot wind, and as that seldom comes more than three or four times in the year, great changes are infrequent. The mean diurnal range in Sydney is 11 1/2°, and taking a series of years it is very unusual for the range on any day to reach 25°.
No; because these are exceptional phenomena. In the late spring and during early summer the climate may be said to be occasionally subject to sharp and sudden changes, which give it the character of variability. But the deviations from mean temperature, except for short periods, are not remarkable.
Yes, in summer; but not in winter.
Certainly not; with the exception of the wide diurnal range of temperature in winter in the southern "continental" districts, as at Cambooya and Thargomindah. The changes are, according to my knowledge, far more sudden and marked in the southern colonies (as during a "shift" from N.E. by W., to S.W. for instance, at Melbourne, and especially at Adelaide) than in Queensland and its coastal districts.