On the conception ‘Fair weather condition’ in atmospheric electricity

Measurements of atmospheric electrical and meteorological parameters during different meteorological conditions indicate that the use of the conception Fair weather condition in atmospheric electricity is discussable. Fair weather contains a very broad stability range, from very unstable to strong stable stability of the atmosphere. For turbulent fluctuations of the electric parameters (the most local variations) the variations are determined by the micrometeorological processes for all stability conditions.These fluctuations represent frequencies greater than one period per four minutes. For lower frequencies (less local variations), however, the stability dependency increases. During stable conditions the electric field and vertical current density were nearly wholly influenced by the charges and their transfer in the nearest layer. During near-neutral and unstable conditions the electrical parameters were influenced by more separated sources. Measurements of how well Ohm's law was fulfilled also indicate the difficulties by using the conception fair weather. The measurements also indicate the importance of taking the convection current density into consideration in studies of the electric charge transfer in the atmosphere.In the more large scale of variations measurements of the electric field by radiosoundings show that 88% of the ionospheric potential is derived from the troposphere, where the meteorological processes are of fundamental character for the atmospheric electrical phenomena. The relatively great stability of the diurnal variation of the large scale or global electric field is also valid for the meteorological processes in this scale of variations.