RESEARCH ON RAIN

Waikato Independent, Volume XLIV, Issue 6076, 14 July 1947, Page 7

RESEARCH ON RAIN

FALLS MORE FREQUENTLY IN INDUSTRIAL AREAS I EXPERIMENTS IN BRITAIN The fact that industrial areas are more subject to rain than country districts has been established in meteorological physics by the Polishborn physical scientist, Dr B. M. Cwilong, who recently arrived from England to take up an appointment at Victoria College, Wellington. Rain falls more in industrial areas, explained Dr Cwilong, because polluted water freezes more readily than pure water. It was found that for the precipitation of rain, snow or hail, the presence of ice crystals in the upper part of the cloud was necessary.

Experiments showed that clouds could remain supercooled, that is, below freezing point for some time without solidifying. Once a certain temperature was reached, however, ice particles would form and quickly spread. Contact with warmer air from the earth would then cause rain to fall.

This minimum temperature in rain, snow and shower clouds has now been fixed! at —41.2 degrees Centigrade for pure water, but for those polluted by industrial fumes it is —32.2 degrees Centigrade, or nine degrees higher. Measurements were taken by Dr Cwilong for these experiments in various parts of England, at the Jungfraujoch' mountain observatory in Switzerland, and during his trip "in the Rangitiki. His researches in this and other atmospheric . conditions twice gained him the Polish. Air Force Medal.

At Oxford, Dr Cwilong also helped to develop a hygrometer, an instrument capable of measuring the humidity of the air up to the lower stratosphere. This was valuable during the war as it allowed aeroolanes to avoid leaving vapour trials behind them.

> An interesting fact revealed by the instrument was the extreme dryness of the stratospheric air above Britain which had led to the assumption that by some movement of air currents this air came from equatorial regions. An automatic hygroscope was also developed for use in radiosondes. These instruments are sent up in balloons to a height of 75 kilometres, and by continuous radio signals record several elements including temperature, humidity, and air pressure, knowledge of the exact temperature! of. the atmosphere made possible mlore accurate weather forecasting.

In spite of recent advances in meteorological physics, Dr Cwilong believes that it is easier to control and direct weather than to forecast it. The complicated factors influencing the heat exchange of the earth and the air which determines the weather are difficult to assess and foretell correctly. Dr Cwilong hopes now to do research into the theoretical basis for the facts revealed by his experiments.