Aircraft observations of electrical conductivity in warm clouds     

P. Ernest Raj  P. C. S. Devar  A. M. Selvam  A.S.R. Murty 《大气科学进展》1993,10(1):95-102

Aircraft observations of electrical conductivity and cloud microphsical, dynamical and other electrical parameters were made in warm stratocumulus and cumulus clouds forming during the summer monsoon seasons (June-September) of 1983 and 1985 in the Deccan Plateau region, India. A Gerdien type cylindrical condenser was used for the measurement of electrical conductivity. The variations in the electrical conductivity are observed to be closely associated with the updrafts and downdrafts in the cloud, liquid water content, cloud droplet charge and coro-na discharge current. The value of electrical conductivity in warm clouds is found to be in the order of 10-12 ohm-1 m-1 which is two orders higher than that observed in clear-air at cloud-base levels in some regions by other investigators.Classical static electricity concepts predict reduced conductivity values inside clouds. Cloud electrical conductivi-ty measurements, particularly in warm clouds are few and the results are contradictory. The recently identified mech-anism of vertical mixing in clouds lends support to coovective charge separation mechanism with inherent larger than clear-air values for cloud electrical conductivity and therefore consistent with the measurements reported herein.  相似文献   

Some geothermal springs of Nepal     

Dinesh Raj Bhattarai 《Tectonophysics》1980,62(1-2)

Almost all known thermal springs in Nepal are localized close to and south of either the Main central Thrust or the Main Boundary Fault, and therefore they fall broadly into two major groups. The results from four thermal springs — two from each group — are discussed here. The temperature of the spring water is up to 50°C above normal atmospheric temperature. The waters of almost all springs are alkaline. The dissolved silica content and atomic ratio of Na and K do not indicate any high subsurface temperature and therefore the thermal springs are considered to be of tectonic origin.  相似文献   

Production estimation of horticultural crops using irs-1d liss-iii data     

P.?P.?Nageswara RaoEmail author  H.?M.?Ravishankar  Uday?Raj  K.?Nagajothi 《Journal of the Indian Society of Remote Sensing》2004,32(4):393-398

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Analysis of the Saharan dust regional transport     

Z. Vukmirović  M. Unkašević  L. Lazić  I. Tošić  S. Rajšić  M. Tasić 《Meteorology and Atmospheric Physics》2004,85(4):265-273

Summary The Balkan Peninsula is situated in the impact zone of Saharan dust storms. The case of Saharan dust transport to Belgrade in the period of 14–17 April 1994 is analyzed using the Eta model for synoptic and meso scale processes. Air back trajectories are calculated at six model levels from 434 up to 5129m with horizontal grid resolutions of 1°×1° and 10×10. Following cyclonic circulation the dust was picked up from North Africa, and transported over Mediterranean. Simultaneously, according to the analysis of the three lowest trajectories, transport of trace metals from Macedonia and southern Serbia by the Koshava wind might be dominant in the observed episode. Turbulent flow enhanced the coagulation process of initially clean dust particles with particles containing Pb and Cd. The coagulation and scavenging processes below and in clouds increased deposition rates of Pb and Cd in Belgrade in the course of wet removal, and consequently trough resuspension processes. Dry deposition samples contained characteristic particles up to 30µm in diameter with Fe content of 11 to 15 atomic% and significant ratio Si/Fe of 3 to 5, determined for selected single particles by the SEM/EDX method. Following dry and wet deposition of Cd and Pb, a residual effect of dustfall is noticed throughout the vegetational period.  相似文献   

Load testing of anchors for wire mesh and cable net rockfall slope protection systems   总被引：1，自引：0，他引：1  

Shanzhi Shu  Balasingam Muhunthan  Thomas C. Badger  Robert Grandorff 《Engineering Geology》2005,79(3-4):162-176

This study presents results of field tests conducted on anchors used to support wire mesh and cable net rockfall protection systems. The load transfer and failure characteristics of these anchors are different from those used in most civil applications in that loads are often applied transversely to the top of tendon rather than axially. The study included vertical as well as horizontal series of tests conducted on some anchors widely used in wire mesh and cable net rockfall protect systems. It was found that the deformation characteristics of these anchors under vertical loading are nonlinear. They are approximated by a hyperbolic formulation and used to calculate the ultimate capacity. Top-downward progressive cracking of the grout was observed during loading and influences the deformation characteristics of these anchors under horizontal loading. The anchors deflected excessively before they could attain their ultimate capacity in the horizontal direction. Based on the field tests, it appears that the deformation under horizontal loading in the systems can be limited by using an enlarged grout zone at the top.  相似文献   

Recession of samudra tapu glacier, chandra river basin, Himachal Pradesh     

Anil V. Kulkarni  Sunil Dhar  B. P. Rathore  Babu Govindha Raj K.  Rajeev Kalia 《Journal of the Indian Society of Remote Sensing》2006,34(1):39-46

Himalayas possess one of the largest resources of snow, ice and glaciers that act as a huge freshwater reservoir. Monitoring the glaciers is important to assess the overall reservoir health of the Himalayas. Samudra Tapu is one of the largest glaciers in Chandra basin of district Lahaul and Spiti, Himachal Pradesh. Based on the field investigations and the remote sensing techniques. features such as accumulation area, ablation area snowline/equilibrium line, moraine-dammed lakes and permanent snowfields were mapped. The glacial terminus was identified using moraine-dammed lake, as lake is located at down streamside of the terminus. The total recession of glacier during the period of 38 years (1962–2000) is about 742 m with an average rate of 19.5 m/yr. In addition, glacial extent is reduced from 73 to 65 km² between 1962 and 2000. suggesting overall deglaciation of 11%. During field investigation. three stages of glaciation using terminal moraine were identified. These moraines were mapped by merging LISS-II1 and PAN data. At the peak of glaciation. the glacial terminus was extended 3.18 km downstream of terminus position in year 2000. Total area during peak of glaciation period has been observed to be 77.67 km², which is 12.67 km² higher than the present glacier extent.  相似文献   

Advances in atmospheric, hydrographic and vegetation remote sensing with lidar     

P C S Devara  P E Raj  G Pandithurai  R S Maheskumar  K K Dani 《Journal of the Indian Society of Remote Sensing》1997,25(4):225-238

Lidar has evolved as one of the powerful and versatile techinqne for atmospheric monitoring and geophysical and hydrographic studies from different observational platforom. This paper discusses the recent advances that have taken place in the lidar technology for rnulti-dimensional atmospheric, hydragraphic and vegetation monitoring together with the results of some specific atmospheric studies carried our for the past ten years using the lider systems built at the Indian Institute of Tropical Meteorotogy (IITm) Pune.  相似文献   

Selection of optimum frequency of a wind scatterometer     

Abhijit Sarkar  Raj Kumar  Mannil Mohan 《Journal of Earth System Science》1988,97(2):192-192

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A study on the sensitivity of the radar scattering coefficient to oceanic winds     

Abhijit Sarkar  Raj Kumar 《Journal of Earth System Science》1985,94(3):249-259

Sensitivity of the radar scattering coefficient to the oceanic wind vector in the midangular range for frequencies from L- to Ku- band is studied. This is based on computations of scattering coefficient via the two-scale scattering theory employing a semi-empirical model for the ocean spectrum suggested by Fung and Lee and the slope distribution by Cox and Munk. Higher frequency and incident angles of over 45 degrees seem to yield better wind sensitivity.  相似文献   

Bianchi Type-III String Cosmological Model with Bulk Viscous Fluid in General Relativity     

Raj Bali  Shuchi Dave 《Astrophysics and Space Science》2002,282(2):461-466

A Bianchi type-III string cosmological model with bulk viscous fluid for massive string is investigated. To get a determinate solution, a supplementary condition B=C ⁿ, between metric potentials, is used whereB and C are function of time alone. The behaviour of the model in presence and absence of bulk viscosity, is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献