A comprehensive model is developed for the calculation of effective attachment coefficient beta(eff) for polluted and unpolluted atmospheres. It is found that beta(eff) depends significantly on the aerosol size distribution. These calculated values of beta(eff) are then used to calculate the various atmospheric electric parameters, viz. conductivity, air-earth current, electric field, and potential over the Indian subcontinent taking into account the earth's orography in 0.5-degrees grid in latitude and longitude as well as the production of small ions due to cosmic rays and radioactivity. The electric parameters are found to increase with the latitude and the altitude of the ground. However, the latitudinal effect is very small compared to the orographic effect. The average electric field is nearly 98 V/m over land and 136 V/m over ocean. The electric field and potential are maximum while the conductivity is minimum during winter. With increase in pollution, current density and conductivity are found to decrease, whereas electric field and potential increase.

Some global electric circuit (GEC) parameters like electrical conductivity, air-earth current, electric field and electrostatic potential etc. have been calculated over Indian subcontinent taking into account the small scale (0.6-degrees grid in latitude and longitude) orographic and latitudinal effects and the base conditions of conductivity profiles. It has been found that the electrical conductivity and air-earth current are larger over mountains than over ocean, while the electric field and the electrostatic potential are smaller over mountains. The theoretically calculated average value of electric field over sea surface is found to be in good agreement with the experimental observations. The values of all the parameters are found to increase with latitude, but the latitudinal variation is observed to be smaller than the orographic variation.

Abstract : A mechanism for propagation of discharge channel inside the cloud is proposed. The mecahnism is based on the motion of charged streamers under the combined influence of cloud-electric field and geomagnetic field. The mechanism gives a theoretical explanation for various experimental observations that most intracloud discharges and incloud portions of ground discharge are oriented roughly horizontally and are always aligned in the same direction.

Electrical and magnetic fields due to arbitrarily oriented lightning over an imperfectly conducting ground have been obtained. The theory has been applied to K-changes, return strokes and horizontal lightning. The results are in good agreement with the experimental observations previously reported by many workers.

The phenomenon of excess point discharge which reports anomalous values of point-discharge for the after-discharge potentials during rapid field-changes, is explained by the development of a transient local potential around the point during such changes. Magnitude of this local potential has been calculated from the concentration of space charge in the field-region of the point. The local potential is found to be -V-V0/4 where V is the pre-discharge potential and V0, the critical potential to start point discharge. The theoretical and observed values of point-discharge currents at after-discharge potentials have also been compared.