80 AUSTRALIAN WEATHER. 



centre is much steeper, and rain has fallen over the south coast 

 generally and extended northwards almost to Central Australia. 



On July 6th at 9 a.m. the weather chart presented the features 

 shown in Chart 19. The cyclone has intensified all round, and 

 has moved rapidly to the east, its centre is just entering 

 Bass' Straits ; very heavy gales from south-west are blowing 

 in the rear of the centre ; heavy rain is falling over Victoria and 

 extends over the greater part of New South Wales. All the winds 

 controlled by this storm were very heavy, and during the 6th 

 July, as the storm passed through Bass' Straits, extremely heavy 

 weather was experienced there. On July 7th it had filled up. 



TYPE IX. TORNADOES. 



These occur during the summer months, and are most frequent 

 in the western plains ; they are developed in hot weather and in 

 the low pressure known as a " Col " between two high pressures, 

 when there is not enough grade to control the winds and the heat- 

 ing power of the sun is great ; if to these there is added the pre- 

 sence of moisture from recent showers, we have all the conditions 

 for the formation of a tornado. The force of wind is often suf- 

 ficient to break off growing trees, two and even three feet in 

 diameter, and the reason there is so little damage to life and 

 property is not the want of power, but the sparse population and 

 the very small number of towns. 



Chart 20, March 20th, 1894. An extensive anticyclone lies 

 south of Australia, giving way in its central parts to an extensive 

 monsoonal dip. The isobars are generally uniform and of even 

 gradients, though a suspicious interval exists to the west of New 

 South Wales between the 30-0 and 29-9 curves. This is un- 

 doubtedly the area in which the secondary developed. Light rains 

 were recorded in New South Wales and Victoria, but in Central 

 Australia temperatures were high. 



Chart 21, March 21st. A marvellous change has taken place. 

 The area of high pressure on the previous day over the Tasrnan 

 Sea has lost two-tenths in pressure. The monsoonal dip so pro- 



