1981 -1990 and 1991 -2000 showed strong decline during the second decade with an average reduction of 5% per two decades. Despite the drastic decrease in S, the all India averaged surface maximum and minimum air temperatures have been increasing. But, the change in increase in maximum temperature from the first decade to second decade is only marginal under the present situation of drastic increase in greenhouse gas emissions, while the increase in minimum temperature has been doubled.
A negative electric discharge voltage generator (NAI Generator) was designed and used to investigate the possibility of reducing (neutralizing) fog, dhoop smoke, and vehicle smoke collected in closed glass containers. The experiment was carried out in a dark room, and two identical glass containers were used. Various sensitivity tests were carried out with fog and smoke. Light intensity was measured for each run as a function of time with and without a negative air ion generator. Negative air ions attach to particulate matter to enhance visibility. At a high negative ion emission rate, the particle mobility becomes sufficient so that particle migration results in their deposition on walls and other indoor surfaces. The performance characteristics of the negative electric discharge generator designed in this work, which produces uni-polar ions by corona discharge at a relatively high emission rate, were evaluated. This device, if operated continuously for six minutes, resulted in the removal of about 93% to 97% of the particles in the glass container, in addition to the natural decay effect. The rate of change of particle removal was higher for fog than for smoke. This study demonstrates that it is possible to neutralize and reduce the concentration of fog and smoke to a significant degree using negative air ions, resulting in increasing visibility in a closed chamber.
Ground‐based observation of OClO, NO2, and O3 columns by differential UV‐Visible spectroscopy at twilight during the fall winter of 1993/94 at the sub‐Arctic station of Reykjavik (64°N, 23°W) are presented. Results show no direct evidence of ozone depletion during the period but significant amounts of OClO were observed in December and January when NO2 abundances were at the annual minimum. NO2 columns are found to be controlled by the hours of light available but highly modulated by the lower stratosphere temperature. OClO was observed outside the vortex as well, but only at times when NO2 was low.
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