ELECTRICAL DISPLAYS

New Zealand Herald, Volume LXXII, Issue 22045, 27 February 1935, Page 12

ELECTRICAL DISPLAYS

CAUSES OF PHENOMENA TYPES OF LIGHTNING THEIR ORIGIN DESCRIBED Electrical storms, and some of the phenomena, real and imaginary, commonly associated with them, were discussed last evening by Professor P. W. Burbidgo, professor of physics at Auckland University College. " We are used to the weather changing fairly quickly, the weather system moving ahout 200 or 300 miles a day, but that does not always occur," Professor Burbidge said, in connection with the continuation of lightning last night after the brilliant display in the early morning. " Occasionally conditions arc more or less stationary, and that is apparently what is happening now. " There is no such thing as a thunderbolt, and the popular idea of something fairly material hurled from the clouds into the earth is incorrect, he continued. " When lightning strikes into the ground you get a little fusing of the earth. This fused mass is known as a fulgurite. Very rarely ' ball ' or ' globe ' lightning occurs. This movea slowly, and floats in the air, and sometimes goes off with a terrific detonation, doing considerable damage. Little is known of this form of lightning, and information about it is being sought. Occasionally you might by chance have a meteorite fall during a thunderstorm, to support the popular fancy of a thunder-bolt. Such a coincidence, however, would be pure chance." Thunder-clouds were formed by upward currents of moisture-laden air ascending rapidly, and developing into the tall cumulus masses seen about Auckland yesterday, he added. Such clouds acted as electrical machines, charging the top and the bottom of the cloud with positive and negative electricity. When these charges reached their limit, so that they could penetrate through the air, they discharged like an electric spark on a huge scale. In this manner discharges resulted from the tops of clouds to neighbouring ones, and from the bottoms of clouds to the ■earth. All lightning except "ball" lightning was of this origin. Very often the flash itself was not seen, only its reflection on the clouds, and this was popularly called "sheet" lightning. " Thunder occurs as the discharge passes through the air, causing intense local heat along its narrow path," he concluded. " This gives a sudden expansion blow to the air, resulting in the crack of thunder. The huge crackling noise is reflected by clouds and the earth to produce the rolling effect." AUCKLAND CONDITIONS

A MIDNIGHT STORM DURATION OF TWO HOURS Following the phenomenal weather conditions which obtained throughout Auckland on Monday afternoon, there was a severe electrical disturbance early yesterday morning, with flashes of vivid forked lightning and loud thunderclaps, commencing about midnight and lasting . for about two hours. The disturbance was accompanied by torrential rain. There was a further electrical disturbance early yesterday afternoon, loud thunder being heard in the eastern suburbs. Threatening conditions continued throughout the afternoon and last night vivid flashes of lightning were seen on the horizon from the city. No further thunder was reported and only light rain fell. The storm yesterday morning covered a wide area and was exceptionally severe on the North Shore. Shortly after one o'clock yesterday morning the electric meters in several houses in Wairoa Avenue, Birkenhead, were blown out, while the valves in wireless sets in the same locality were damaged. No further damage was reported in the area controlled by the Waitemata ElectricPower Board.

In the districts served by the Auckland Electric-Power Board no damage occurred, although one of the officers at the. power station at King's Wharf stated that several surges were experienced on the high-tension lines between Arapuni and Penrose during a disturbance at seven o'clock on Monday evening. They were almost instantaneous, but no damage was done. During the severe storm about midnight the Westfield fender tripped out, but came back automatically almost immediately.

The thunder was not like the usual dull rumblings, but seemed to come from directly overhead in sharply-de-fined claps. The lightning made an impressive sight against a mass of lowering black clouds, and the sky at times was ablaze with vivid flashes. Heavy rain fell continuously for about an hour and a-half after midnight, but at about two o'clock the storm eased off.