A study of point discharge current observations in the thunderstorm environment at a tropical station during the year 1987 and 1988

The results of the measurements of point discharge current observations at Pune, India, during years 1987 and 1988 are presented by categorizing and studying their number of spells, polar current average durations, and current magnitudes in day-time and night-time conditions. While the results showed that the thunderstorm activity occupies far more day-time than the night-time the level of current magnitudes remains nearly the same in the two categories

Opinion Poll on Use of ICT in Commerce Education: A Reality Check

Ratnagiri is a coastal district belonging to Konkan region of Maharashtra state, situated on the western coast of India. The district comprises of 9 tehsils viz., Mandangad, Khed, Chiplun, Sangameshwar, Lanja, Rajapur, Ratnagiri, Guhagar & Dapoli. Ratnagiri district has few colleges delivering higher education in Commerce which fall under Mumbai University, one of the oldest and pioneering universities in India. Commerce education here is not yet ICT driven. But UG students here are interested in ICT based Commerce education as it is an urgent need of the present day. To satisfy this requirement it is necessary to attract, nurture and develop faculty members accordingly. There is an urgent need to change the mindset of all those involved in Commerce education system to make this revolution a dream come true. There are many business opportunities in Ratnagiri district but they remain unexplored due to old and traditional business practices and methodologies. These units can be transformed into modern era high tech based performing units but the potential i.e. Commerce students need to be well-equipped for the same. This paper highlights the opinions of Commerce students with reference to integration of ICT and skills necessary in Commerce education

The Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX): overview and preliminary results

While the demand for enhancing rainfall through cloud seeding is strong and persistent in the country, considerable uncertainty exists on the success of such an endeavour at a given location. To understand the pathways of aerosol-cloud interaction through which this might be achieved, a national experiment named Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX) in two phases, was carried out. The rationale of CAIPEEX, the strategy for conducting the experiment, data quality and potential for path-breaking science are described in this article. Pending completion of quality control and calibration of the CAIPEEX phase-II data, here we present some initial results of CAIPEEX phase-I aimed at documenting the prevailing microphysical characteristics of aerosols and clouds and associated environmental conditions over different regions of the country and under different monsoon conditions with the help of an instrumented research aircraft. First-time simultaneous observations of aerosol, cloud condensation nuclei (CCN) and cloud droplet number concentration (CDNC) over the Ganges Valley during monsoon season show very high concentrations (> 1000 cm-3) of CCN at elevated layers. Observations of elevated layers with high aerosol concentration over the Gangetic valley extending up to 6 km and relatively less aerosol concentration in the boundary layer are also documented. We also present evidence of strong cloud- aerosol interaction in the moist environments with an increase in the cloud droplet effective radius. Our observations also show that pollution increases CDNC and the warm rain depth, and delays its initiation. The critical effective radius for warm rain initiation is found to be between 10 and 12 µm in the polluted clouds and it is between 12 and 14 µm in cleaner monsoon clouds

The cloud aerosol interaction and precipitation enhancement experiment (CAIPEEX): Overview and preliminary results

While the demand for enhancing rainfall through cloud seeding is strong and persistent in the country, considerable uncertainty exists on the success of such an endeavour at a given location. To understand the pathways of aerosol-cloud interaction through which this might be achieved, a national experiment named Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX) in two phases, was carried out. The rationale of CAIPEEX, the strategy for conducting the experiment, data quality and potential for path-breaking science are described in this article. Pending completion of quality control and calibration of the CAIPEEX phase-II data, here we present some initial results of CAIPEEX phase-I aimed at documenting the prevailing microphysical characteristics of aerosols and clouds and associated environmental conditions over different regions of the country and under different monsoon conditions with the help of an instrumented research aircraft. First-time simultaneous observations of aerosol, cloud condensation nuclei (CCN) and cloud droplet number concentration (CDNC) over the Ganges Valley during monsoon season show very high concentrations (> 1000 cm-3) of CCN at elevated layers. Observations of elevated layers with high aerosol concentration over the Gangetic valley extending up to 6 km and relatively less aerosol concentration in the boundary layer are also documented. We also present evidence of strong cloud- aerosol interaction in the moist environments with an increase in the cloud droplet effective radius. Our observations also show that pollution increases CDNC and the warm rain depth, and delays its initiation. The critical effective radius for warm rain initiation is found to be between 10 and 12 μm in the polluted clouds and it is between 12 and 14 μm in cleaner monsoon clouds

A case study of weekday variations in electrical parameters at Athens

153-157Ground-based daily hourly data on atmospheric electrical parameters for the year 1975 at Athens basin, a densely industrialized location, were examined for the identification of the effects of industrial pollutants on electrical parameters during weekdays. The results showed that on Sundays the average values of conductivity and potential gradient were 12% higher and 10% lower, respectively, than the annual mean and on Mondays these values were lower and higher, respectively, by about the same value. The analysis of the data suggested that on Sundays and Mondays alone, the variations noticed in the electric parameters were opposite and extreme in nature, perhaps suggestive of an inherent 7-day periodicity in them. The possibility that this periodicity may also correspond to the solar-sector-boundary-crossing events was also verified

A study of the association of surface potential gradient with the onset of monsoon at Pune

349-354Simultaneous measurements of fair weather surface potential gradient, vapour pressure, westerly wind (speed and direction), mean sea level pressure, and dry bulb temperature at Pune (18°32 'N, 73°51 'E: 559 m AMSL) during April-June of 1973-77 were analysed and examined for monthly and seasonal variations. The results suggested about 17 and 50% diminution in potential gradient in May and June over the period of study with respect to the values in April and about 50 to 100% increase only in vapour pressure and westerly wind among other meteorological parameters. This was suggestive of their preferential influence to decrease the potential gradient. The study also showed that the year to year lower or higher monthly mean value of potential gradient bore a fairly good correspondence with the early or late onset of monsoon. This was suggestive of about 25% and 10% higher values of potential gradient in April and May than the net average for delay in monsoon by about a week

Estimation of electrical charges deposited to the ground by lightning in thunderstorms at Pune

297-307Ground-based data of electric field measured at Pune during lightning events of nine thunderstorms have been analysed to obtain the spatial and temporal variation of the charges that are deposited to the ground. The results are based on some assumptions such as the large transient changes in electric field of at least 1 kVm-1 for which the flash of lightning was visible and the subsequent sound of the thunder was well heard. The inner-storm average charge per flash varied in the range -19 to -147 and +19 to +44 C and the storms aggregate mean values were -42 and + 37 C per flash. The spatial variation suggested that the radial distance of the lightning-strike underneath the storm tended to cluster within the distance of 6 km. The time variation of the charge and strike distance underneath the storm showed localization of radial strike distances associated with the increase in charge values. The study has also permitted one for the direct validation of the analytical result of Malan [Physics of Lightning (The English Uni Press, London), 1963, p. 30] that the value of the electric field (sin q cos2q) at a fixed location due to the vertical motion of the charge exhibits maxima when tan q (= H/D) is 0.707

Small ion mean lifetimes at five typical locations in Indian region

347-348Small ion mean lifetimes at five typical locations (rural, oceanic, hilltop, urban and industrial) in the Indian region have been obtained using Aitken nuclei concentrations. It is noted that the derived values of mean lifetimes at urban and industrial locations are much less than those at rural and oceanic locations