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  • Author or Editor: Bh V. Ramana Murty x
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L. T. Khemani
and
Bh V. Ramana Murty

Abstract

The rainfall data, for the period 1901–69, of three stations in the region downwind of the urban industrial complex at Bombay and of two stations in the nearby non-urban region, have been analyzed. The study has indicated that, with respect to the non-urban region, the region downwind of the urban industrial complex recorded an increase of rainfall by about 15%, significant at less than the 1% level, during 1941–69 which is the period of increased industrialization.

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K. Rupa Kumar
,
L. S. Hingane
, and
Bh V. Ramana Murty

Abstract

Variation of air temperature at the surface and at four levels in the troposphere, viz., 850, 700, 500 and 200 mb, over India have been studied using the data at ten radiosonde stations for 31 to 42 years during 1944–85. Seasonal as well as annual mean temperature series have been obtained, and the general feature of the variations are discussed. Quantitative study of the temperature changes is made by evaluating the linear trends.

Surface temperatures do not show appreciable trends during the last three decades over India, but at the upper levels there was a trend reversal around 1958, from warming to cooling. There is a distinct contrast between the northern and southern Indian stations during 1958–85, in that the former have shown significant cooling while the latter have shown no trends. Port Blair, the island station considerably south, however, shows slight cooling during this period. The rate of cooling increases with height, particularly at the northern stations. There is no marked interseasonal contrast in the temperature trends at upper levels.

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A. S. Ramachandra Murty
,
A. M. Selvam
, and
Bh V. Ramana Murty

Abstract

Measurements of cloud liquid water content and temperature were made along with visual observations in 32 traverses carried out in six warm cumulus clouds subjected to salt seeding. The results showed (i) a rise, of 1–2°C, in temperature, (ii) an increase, sometimes exceeding 200%, in liquid water content, and (iii) vertical growth, up to 60%, in seeded clouds which developed rain. The features noticed could be due to the possible dynamic effect of salt seeding in warm clouds.

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K. R. Biswas
,
R. K. Kapoor
,
K. K. Kanuga
, and
Bh V. Ramana Murty

Abstract

An experiment on artificial stimulation of rain using a warm cloud seeding technique was undertaken in three nearby climatologically similar regions, Delhi, Agra and Jaipur in northwest India. Analysis of the data from 18 experiment-seasons has suggested a positive trend of the result, which is found significant by statistical tests.

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A. S. Ramachandra Murty
,
A. M. Selvam
,
R. Vijayakumar
,
S. K. Paul
, and
Bh V. Ramana Murty

Abstract

Electrical and microphysical measurements were made in warm maritime and inland cumulus clouds, before and after seeding, by repeated aircraft penetrations at a single level, a few hundred meters above cloud base. Such measurements were also made in non-seeded clouds by single penetrations during transient flights.

The electric field initially was negative in the maritime clouds which developed rain. In the cloud case which dissipated without rain it was initially positive. The field showed sign reversal with time, occasionally preceded by intensification, in all maritime clouds. The field initially was positive in inland clouds. It showed no time variation except in one cloud case where both positive and negative fields were recorded during the period of heavy rain.

The droplet charge, droplet median volume diameter and liquid water content showed no marked time variation in either maritime or inland clouds. However, in the cloud case which developed heavy rain marked increases in droplet median volume diameter and liquid water content were recorded.

The time variations of electrical and microphysical parameters following seeding are in general within the range of their natural variability.

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