Fog often represents a major problem for a number of activities. Examples of this are various forms of transport and outdoor activities such as sports meetings and the like. Fog constitutes a serious problem for air traffic in particular. When airports have to close due to fog, this entails major expenses and delays for the passengers. In addition the diminished visibility represents a considerable increase in the risk of accidents for all transport, not only for air traffic.

It is well known in the art that fog can be cleared from, e. g. airports by the dispersal of a fog-dissipating material from an aircraft, rocket or gun, thus causing the water particles in the fog to condense and fall as rain or snow. In the literature there are described a number of different suitable materials which, when dispersed over an area, will increase the precipitation of the fog's/clouds'water particles, such as various bromides, iodides, sulphates, nitrates, chlorates and perchlorates of alkaline metals as well as AgI and AgBr. The common factor for these compounds is that they are toxic and thus have undesirable and harmful effects on the environment exposed to them.

This can represent a substantial problem for areas which require frequent fog clearance. The silver compounds are also extremely expensive, and the sulphates and nitrates cause acidification of the precipitation.

In Norwegian patent no. 176 727 the applicant has described the use of dry ice for dispelling fog. This is an environmentally friendly material, but is encumbered with the disadvantage that it is only effective on fog/clouds which are colder than-2°C.

It is an object of the present invention to provide a method for dissipating or dispelling fog and/or clouds which are warmer than-2°C in an environmentally friendly manner, and which does not have any harmful effects on animal and plant life in the area which is exposed to the method.

The object of the invention is achieved by scattering potassium formiate in powder form on the fog/clouds which have to be dispelled. After testing various harmless materials over a period of several years, it has been found that potassium formiate is especially suitable for increasing the precipitation of water particles at temperatures over-2°C, particularly in the range +2 to +4°C. Alternatively, a block of pressed potassium formiate can be disposed immediately above the area which has to be treated and detonated, thereby pulverising the potassium formiate and dispersing it over the area.

A number of methods are described for bringing the fog-dissipating material to the fog. The present invention employs the prior art for positioning the potassium formiate, and therefore this will not be described further.

Reference should be made to the use of an aircraft/plane or to a gun as described in Norwegian patent no. 176 727.