Lighting, Maj 1997

This subcomponent is aimed at organization in Poland of the system for thunderstorm and lightning detection. The system will be a part of the countrywide system for natural disaster warning and management. It seems a certain paradox that the more developed the economy, the greater vulnerability to the phenomena, such as lightning. 50 years ago a lightning strike would set fire to a house damage a transformer, etc. The losses incurred, as result of e.g. power failure would not be substantial. This has changed entirely following ubiquitous introduction of electricity and computers. The overvoltage caused by a lightning strike may disturb life in huge metropolitan areas and halt factories. Thunderstorms continue to pose threat for aviation and the energy sector. The failures caused by a lightning result not only in sizeable economic losses, but also endanger human life.

Lightning cloud-to-cloud and cloud-to-ground, Maj 1997

In Poland, at the meteorological stations, the thunderstorm activity is determined visually, i.e. through the recognition of the thunderstorm occurrence; nonetheless no system is in place, enabling quantitative and qualitative analysis of this phenomenon. Meteorological stations record thunderstorms occurring in their vicinity. In Poland, the average distance between meteorological stations is 70 kilometres, whereas the average size of a single thunderstorm cloud spans between a few and over 10 kilometres. Hence the obvious inability of the surface observation system to detect majority of thunderstorms. Between 1985 and 1989 the incidental attempts were made to locate the thunderstorms using radio noise direction finding equipment. Apart from that no research were made relating to the lightning location and its type identification. Starting from 1992 onwards in recognition of the future thunderstorm information importance the IMWM has been involved in a number of projects aimed at the establishment of the countrywide network of the lightning remote sensing. These projects have not resulted in any system establishment, mainly due to financial reasons, nonetheless enabling understanding of the technology options offered.

In many countries, including the EU, there exists and are operated the systems for lightning detection, location and record. The map of these systems' operations covers the entire USA, Mexico, the inhabited areas of Australia and the entire Western Europe, including Scandinavia. Last year the system installation started in Hungary and currently, the Czech and Slovak contemplate it. Lasting experience of the countries operating such systems confirm their usefulness for the purpose of lightning warning and hazard prevention.

As per the data available in the US, 100 persons die each year hit by a lightning, whereas between 325 and 500 are harmed to some extent. Material losses caused by lightning strikes are estimated at over US $300 million. This is rather an underestimation, since not all cases are recorded. The recorded losses are estimated at 40 per cent. of the total. The scale of the problem may be depicted by the fact that between 1992 and 1995 the US National Lightning Detection Network was detecting the average of 21 746 000 cloud-to-ground lightning per annum. The Hungarian lightning detection system recorded 240 000 during only one thunderstorm, lasting for a few days.

The lightning detection and location system should cover the entire Poland, and detect both the, or cloud to cloud and cloud to ground, lightning. The accuracy of lightning location should be equal to, or greater than 1 km. The system should enable superimposition of the detected lightning location onto the map of Poland, with colour coding of the lightning occurrence time and type. It should generate data in the form of a file including the lightning time, date, altitude and longitude, the charge and amplitude, in other words the signal strength for each lightning.

One of the most difficult tasks of the contemporary meteorology is precipitation forecasting, in particular form convective clouds. In order to forecast the precipitation from such clouds it is necessary to understand the stage of their development. The information may be provided by the system for lighting detection and location. According to the current decade research, the electric phenomena occur at early stage of the convection cloud built up. The phenomena intensity increases in line of the cloud enlargement, reaching the level of internal or cloud-to-cloud lightning and the groundbound lighting. The internal lightning accounts for between 70% to 99% of the total lightning within the given thunderstorm process. The remainder is the cloud-to-ground lightning. In principle, such lightning initiate at the matured stage of the convection cloud development, reaching the maximum 10 to 15 minutes before the cloud enters into the disintegration stage. The cloud disintegration stage is accompanied with dangerous atmospheric phenomena, such as showers, hail, strong descending air steams, etc. This was the case between 22 and 23 of July 1997 in Kotlina Kłodzka. Few people died and material losses were substantial. The capacity of monitoring the electric phenomena inside the cloud enables forecasting of the related phenomena, such as intense atmospheric precipitation zones. The lightning detection and location systems enable diagnosis of the thunderstorm situation with a greater advance than provided by the other remote sensing systems (e.g. the radar), thereby the greater advance of the forecast relating to hazardous atmospheric phenomena, including intense precipitation. This is of substantial importance for the flood hazard forecasting.