CHARGES ON PARTICLES OF DIFFERENT SIZE FROM BUBBLES OF MEDITERRANEAN-SEA SURF AND FROM WATERFALLS

The Blanchard effect over the oceans is a generally known phenomenon and is presumed to be a source of positive charges on salt particles from bubbles in oceanic sea surf. Confirmatory measurements of particle charges in the laboratory made by Blanchard were, however, restricted to particles of more than 3 mum in diameter. A number of authors have actually found an increased positive net space charge in the whitecap and surf areas of the large oceans by applying the Faraday-cage method. Because this method is subjected to a number of disadvantages, it seemed essential to measure the charges on surf particles directly and then, in contrast to Blanchard, in size fractions from 2.5 down to 0.2 mum in diameter and under natural surf conditions very near to the source of the particles. For this purpose a four-stage filter device was applied on an unpolluted Mediterranean Sea beach when the water was agitated. It appeared that in agreement with Blanchard, while the sea spray particles of more than 2.5 mum diameter indeed carry positive charges, in contrast, the smaller particles down to 0.2 mum and with a much higher particle number density are negatively charged. As a result, in the layer above the agitated ocean, only a negative space charge and a negative electric field exists. This is in contrast to the findings of a number of authors who have made measurements on the Atlantic and Pacific oceans from which a positive space charge and a positive field appeared. The opposite polarity found on the Mediterranean Sea seems to be caused by its significantly higher salinity and this could be confirmed by laboratory experiments. The results of the present author's measurements demonstrate that the ''classical picture of the Blanchard effect'' cannot be applied for every oceanic region. Near a waterfall, the well-known Lenard effect was confirmed.