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Current Research Paper
the antenna, is obtained by a measurement of potential
difference between the antenna and the surface and
thereby to measure the atmospheric electric field. The
observations at several heights allow micrometeorologi-
cal processes to be investigated. This battery-powered
electrometer is preferable to a commercial laboratory
device both because of cost and ability to cheaply re-
place the front-end amplifier chip damaged by tran-
sients. By setting up systems for the measurements of
conductivity and current this system can be used to verify
the Ohm’s law J= óE.
Simpson[18] observed that blizzards are intensely
electrified and produce high positive potential gradients
on the ground. In our observations we observe that
whenever high winds are accompanied with some snow-
fall, i.e., atmospheric Maxwell current, Air-earth-cur-
Figure 9(b) : Variation of GEC parameters during bliz- rent, electric field of all the three categories begin to
zard day. decrease about 3 – 4 hours before the appearance of
the columnar resistance, induced by the atmospheric blizzard. For example, on December 28, 2008, winds
suspension content and its vertical transport, may be begin to strengthen at 1200 UT and blizzard started
expected to dominate the vertical current and its varia- from 1500 UT shown in Figure 9(b). Devendraa Siingh,
tions. Thus the behavior of I depends on whether the Vimlesh Pant and A K Kamra made similar observa-
percentage changes in V or R dominate. Over the con- tions at the same place in summer 2005 on atmospheric
tinental stations one can expect that the changes asso- air-earth current density, temperature are below freez-
ciated with R are larger than those associated with V[12]. ing point, positive ion concentration of all four catego-
Gringel et al.[7] showed that the first two km of the ries begin to decrease 3-4 hours before the onset of
atmosphere contribute about 50 percent to the total blizzard. The decrease observed in all types atmospheric
columnar resistance and the first 13 km about 95 per- electrical parameters during snowfall indicates that snow
cent. With observations conducted at Weissnau, Ger- particles effectively scavenge the ions. The fact that the
many, Gringel et al.[7] measured a variation in R of about air-earth current density and electric field almost re-
30 percent, and attributed the variation to a changing duces to zero value indicates that scavenging of atmo-
ionization near ground and by varying aerosol concen- spheric ions is almost total at that time. The observa-
trations in the lower troposphere. Muir[14,15] tried to tions that the decrease in different ion categories is not
explain it on the basis of sunrise effect at the height of always parallel to each other are likely to result from
electrosphere leading to build up of a potential through the non-uniform rate of scavenging of the ions of differ-
dynamic motion associated with tides. ent sizes. This observation can be used as a forecasting
Monitoring atmospheric electrical parameters dur- for the convoy persons and other activities around Maitri
ing clear sky days has been achieved by this system for human safety and preliminary percussions. The de-
Panneerselvam, et al.[16]. This present electrometer de- tailed mechanisms underlying the formation of severe
sign can measure potentials safely at a height of up to blizzards are not yet well understood and form one of
2m only. In future with suitable modifications in the elec- the interesting topics for future polar research.
trometer front end, so as to measure the potential up to Surface atmospheric electrical parameters were
60kms using electrometer as a play load in balloons found to be sensitive to convective clouds, fog, rain
and rockets. Making suitable modifications in the elec- and snow. The variations of electrical parameters will
trometer can be used to sense lighting clouds well in always be in the positive side, and goes to well in nega-
advance so as to make it as a lighting warning device. tive side at about 3 hours before the onset of a blizzard
The potential of the atmosphere, at the same height as at the measuring site. Hence at high latitude station
Environmental Science
An Indian Journal
