Effect of relative humidity on the angular distribution of scattered light intensity for rural and urban aerosols

The change in atmospheric relative humidity affects the physical and optical properties of aerosol particles. It would be interesting to study the effect of an increase in relative humidity on the angular scattering of light by aerosols (by incorporating the changes due to it as the complex refractive index and the parameters of the size distribution function). In the present paper we have computed the angular scattering function for rural and urban aerosols, for light of wavelength 0.55 μn. The results obtained for these two models, representative of different environments, are interesting and show some discriminating features.     

Kolmogorov constants for CO2, wind velocity,air temperature,and humidity fluctuations over a crop surface

The Kolmogorov constants for CO₂, wind velocity, air temperature, and humidity fluctuations were evaluated from measurements made over soybean and grain sorghum fields and found to be 0.78 ± 0.11, 0.49 ± 0.08, 0.70 ± 0.15, and 0.99 ± 0.16, respectively. These results are consistent with recent observations reported in the literature.Published as Paper No. 7255, Journal Series, Nebraska Agricultural Experiment Station. The work reported here was conducted under Regional Research Project 11-33 and Nebraska Agricultural Experiment Station Project 27-003.Associate Professor and Post Doctoral Research Associate, respectively, Center for Agricultural Meteorology and Climatology, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, NE, U.S.A., 68583-0728.     

Gravity anomalies and the Indian lithosphere: Review and analysis of existing gravity data

The upper part of the lithosphere has been actively involved in various exogenic and endogenic processes which have left their imprint on the gravity field on the Indian Peninsula and the Himalaya. Analysis of the gravity field over the Dharwar craton shows that the greenstone belts of this craton have been formed as a result of development of deep fractures in the earth's crust during Archaean times. Precambrian mountain ranges such as the Aravallies, Vindhyans, Satpura and Eastern Ghats are located peripheral to Archaean cratons. Most of these mountain belts are characterized by gravity highs suggesting that the underlying crust is of higher than normal density. These mountain ranges with the exception of the Eastern Ghats do not appear to be locally compensated. Regional compensation seems to prevail over all these areas. Eastern Ghats ranges are also underlain by a crust of higher than normal density relative to the Dharwar and Bastar cratons and exist with a sharp contact with the cratons in the West. Isostatic compensation in the Eastern Ghats appears to have been achieved by thickening of the underlying crust. The Himalaya has attained a fairly high degree of isostatic compensation.     

Some theoretical aspects of electric field and precipitation growth in a finite thundercloud

A time-dependent numerical model allowing a simulation of the electric field and precipitation growth in a thundercloud of finite dimensions is described. It is found that slower growth rate (compared to an infinite thundercloud) of the electric field in a finite thundercloud permits larger size growth and higher terminal velocities of hydrometeors owing to an enhancement in precipitation intensity. Calculations also show that a higher maximum of the electric field is needed to slow down the larger particles produced in a thundercloud of finite dimensions. In particular, these solutions also include contribution of screening charge transport in thundercloud electrification.     

Gravity field and structures of the Rajmahal Hills: Example of the Paleo-Mesozoic continental margin in eastern India

A narrow strip of Gondwana basins separates the Rajmahal traps from the peninsular shield in eastern India. This part of the shield margin is associated with a conspicuous gravity high of 100 km wavelength and 48 mGal amplitude over an area of 25,000 km². Second order residual anomalies due to Gondwana sediments and traps are superposed on this wider gravity high. Gravity interpretation, partly constrained by seismic data, suggests that the wider high is caused by a denser metamorphic layer (amphibolite and granulite) up to 3.5 km thick. The metamorphic layer also extends below the eastern Rajmahal hills where the Gondwanas, traps and younger sediments have covered it. The Gondwanas are downfaulted against the shield edge and are preserved over an irregular basin floor whose deepest part underlies the eastern flank of the Rajmahal hills adjacent to the Bengal basin. It is inferred that the Gondwanas were deposited over a rifted and highly faulted shield margin that was intruded by the Rajmahal traps nearly 100 m.y. ago. High-grade metamorphism along the shield edge presumably preceded the continental rifting, perhaps occurring in the Precambrian as a part of the Eastern Ghats orogeny, along the east coast of India.     

Condensed water in tropical cyclone “Oliver”, 8 February 1993

On February 8, 1993, the NASA DC-8 aircraft profiled from 10,000 to 37,000 feet (3.1–11.3 km) pressure altitude in a stratified section of tropical cyclone “Oliver” over the Coral Sea northeast of Australia. Size, shape and phase of cloud and precipitation particles were measured with a 2-D Greyscale probe. Cloud/ precipitation particles changed from liquid to ice as soon as the freezing level was reached near 17,000 feet (5.2 km) pressure altitude. The cloud was completely glaciated at −5°C. There was no correlation between ice particle habit and ambient temperature. In the liquid phase, the precipitation-cloud drop concentration was 4.0 × 10³ m⁻³, the geometric mean diameter D_g=0.5−0.7 mm, and the liquid water content 0.7−1.9 g m⁻³. The largest particles anywhere in the cloud, dominated by fused dendrites at concentrations similar to that of raindrops (2.5 × 10³ m⁻³) but a higher condensed water content (5.4 g m⁻³ estimated) were found in the mixed phase; condensed water is removed very effectively from the mixed layer due to high settling velocities of the large mixed particles. The highest number concentration (4.9 × 10⁴ m⁻³), smallest size (D_g=0.3−0.4 mm), largest surface area (up to 2.6 × 10² cm² m⁻³ at 0.4−1.0 g m⁻³ of condensate) existed in the ice phase at the coldest temperature (−40°C) at 35,000 feet (10.7 km). Each cloud contained aerosol (haze particles) in addition to cloud particles. The aerosol total surface area exceeded that of the cirrus particles at the coldest temperature. Thus, aerosols must play a significant role in the upscattering of solar radiation. Light extinction (6.2 km⁻¹) and backscatter (0.8 sr⁻¹ km⁻¹) was highest in the coldest portion of the cirrus cloud at the highest altitude.     

Evaluation of the Relative Resistance of Twelve Species of Fish in Toxicity Bioassays with Electroplating Waste

The present paper deals with the evaluation of the relative resistance of 12 species of fish in static toxicity bioassay tests of electroplating waste. The electroplating waste is highly toxic as it contains several toxic metals like copper, nickel, cadmium, zinc, lead and chromium alongwith cyanides, acids and alkalies. On the basis of TL₅₀, the fish Clarias batrachus ist the most resistant fish and Labeo rohita the most sensitive. The relative resistance of the fish is in the decreasing order: Clarias batrachus, Saccobranchus fossilis, Ophiocephalus gachua, Ophiocephalus punctatus, Puntius stigma, Puntius sophore, Mystus vittatus, Cyprinus carpio, Colisa fasciatus, Notopterus notopterus, Cirrhina mrigala and Labeo rohita.     

Geophysical surveys in Parvati valley geothermal field, Kullu, India

Direct current resistivity surveys and shallow temperature measurements were carried out for geothermal exploration in a part of Parvati valley, goethermal field, Himachal Pradesh, India. At a few places, the Schlumberger soundings pointed to the presence of a relatively low-resistivity shallow layer, which probably represents fractured and jointed quartzite, saturated with hot/cold water. Wenner resistivity profiles indicate the presence of some possible shallow subsurface lateral hot water channels across the valley at Manikaran. Shallow temperature measurements show a good subsurface thermal anomaly near the confluence of the rivers Brahmaganga and Parvati. The results of the survey, together with other available geodata, suggest that an anomalous heat source does not lie beneath the study area.It is postulated that the meteoric water, originating at high elevations after heating as a result of circulation at depth, emerges at the surface in the Parvati valley as hot springs, after mixing in various proportions with near surface cold waters.     

Geochemistry of Los Humeros Caldera,Puebla, Mexico

Geochemistry of Pliocene to recent volcanic rocks from Los Humeros caldera (19°30′ N – 19°50′ N and 97°15° W – 97°35′ W) in East-Central mexico is described. The volcanic rocks from this area seem to represent both alkali and high-alumina basalt series, or both calcalkaline and high-K calc-alkaline sequences. The available bulk-chemical analyses (23 this study and 18 from unpublished literature) show that the entire sequence of rocks from basalts to rhyolites are present in this area. Different degrees of partial melting of the source region followed by extensive shallow-level crystal differentiation seem to have taken place before most volcanic eruptions. These processes are perhaps the most important mechanisms for magma genesis in Los Humeros caldera. Geophysical studies in this area are not sufficient and more detailed geophysical surveys and a better geological interpretation are needed in order to delimit the underlying magma chamber.     

Gravity interpretation of the Dharwar greenstone-gneiss-granite terrain in the southern Indian shield and its geological implications

The Dharwar craton in the southern Indian shield has a wide distribution of volcano-sedimentary sequences surrounded by a vast gneissic complex, both of which have been intruded by younger granites. A gravity anomaly map of this craton, compiled from all the available data, is analysed here to study the structures and depths of the greenstone belts, the mode of granite emplacements and the greenstone-gneiss-granite associations in general. The anomaly map is a mosaic of well-defined gravity highs and lows characterizing the dense volcano-sedimentary sequences and exposed and/or concealed granites respectively. Gravity modelling indicates that the Shimoga belt has a limited depth range of only 3–4 km while the Chitradurga and Sandur belts have greater depths of over 10 km. The structures inferred for the Dharwar formations are alternating bands of synclines, filled with dense schistose rocks, separated by anticlinal ridges of gneisses and granites.