H. S. Rathor

On frequency magnitude and energy of significant Indian earthquakes

SummaryFrequency, magnitude and energy of Indian earthquakes with magnitude greater than 5 has been studied. The Indian regions can be divided into three main seismically active regions, viz. 1. Delhi and Himalayan region, 2. Assam region and 3. Koyana region which includes southwest India. The relations between frequency-magnitude and energy-magnitude of earthquakes are shown in Fig. 3 and 4 respectively. Further a relationship, logN=p+q logE type has been established for frequency and energy of Indian earthquakes and the values of constantsp andq have been determined for all the three seismic regions. The results thus obtained are good and satisfactory.

Vertical velocity due to mean baroclinicity and diabatic heating of the atmosphere

SummaryVertical velocities at the 800, 600 and 400 mbar surfaces over India have been calculated, making use of a 3-level geostrophic baroclinic model. Further, the effects of non-adiabatic heating is included into the model and vertical velocity due to diabatic heating is obtained for the same period. A numerically obtained vertical velocity field due to baroclinicity and diabatic heating is seen to be in agreement with the observed weather patterns.

Upper air mean dry-bulb and dew-point temperature profiles over Gauhati airport

SummaryThe best fit curves for upper air mean dry-bulb and dew-point temperatures over Gauhati airport (26°05′N, 91°43′E, 49 metres a.m.s.l.), for the month of April, have been calculated with the equation,x=A+By+Cy2,y being the log value in mb of the isobaric level under consideration andx, the mean dry-bulb or dew-point temperature as the case may be, at the isobaric level under consideration. The values of constantsA, B andC for morning dry-bulb and dew-point curves come to be −29.54559, −93.65766 and +37.35048 and −118.84791, −31.15503 and +25.63585 respectively and values of these constants for evening curves come to be −35.86214, −94.15694 and +38.61870 and −127.55970, −29.97192 and +26.36538 respectively. These best fit curves help in finding out mean desired temperatures at any isobaric level in forecasting of thunderstorms and hailstorms, at a station, by dry-bulb and dew-point temperature anomaly technique propsed earlier by the authors.

Interpretation of gravity and magnetic anomalies caused due to spherical bodies

SummaryThe method of continuation has been used to obtain the master curves for gravity and magnetic anomalies caused by spherical bodies. The procedure to calculate the depth of burial and radius of spherical bodies has been outlined.

Reduction of the complete omega equation to the simplest form

SummaryUsing the vorticity and the thermodynamic equation, ‘Omega Equation’ has been derived. The effect of friction is not taken into account. The vertical velocity omega (ω) is composed of two parts, viz. mean baroclinicity in the atmosphere and heating. The baroclinicity part includes three terms. The magnitude of the second term is of the order of 10−10 to 10−12 mb−1 sec−2,and that of the last is 10−10 to 10−12 mb−1 sec−2, whereas the first term is of the order of the vertical velocity omega 10−4 to 10−6 sec−1. Therefore, the higher order terms can be omitted. Thus with the above approximation the complicated expression for omega is reduced to a simple form.

On the evaluation of natural illumination from pyrheliometric measurements in India

SummaryThe technique for evaluating the natural illumination of direct solar radiation introduced byÅngström andDrummond [1]2) has been applied by the authors to the pyrheliometric observations in India and the values of natural illumination derived at eight representative stations are presented in this paper. The dirunal and seasonal variations of the illumination fluxes have been discussed. —In general, illumination fluxes in India show a maximum during summer season except at Madras, where the maximum occurs during winter. The illumination fluxes at various stations vary within the range 80–110 kilolux throughout the year. However, at Calcutta, it varies within a rather narrow range of 65–85 kilolux. Both in summer and winter, the illumination flux during forenoon hours is usually more than that during afternoon hours. An increase in daylight illumination is observed with height of the station above sea level.

On the evaluation of planetary albedo of the earth from turbidity measurements in India

SummaryThe planetary albedo of the earth has been evaluated from the turbidity measurements in India by usingÅngströms empirical relation [1]2) and the same has been presented in this paper. The diurnal and seasonal variations of the planetary albedo have been discussed. It has been found that during the morning hours, albedo is usually more than that during afternoon hours. Further, it shows a minima during winter season and a maxima during hot summer months.

A resistivity computation method for layered earth models with transition boundary

SummaryA theoretical solution is obtained for the problem of a three and four layered earth model with transitional boundary. In practice, the transition layer can stand for fresh water bearing sand and fine gravels. The master curves for Schlumberger electrode configuration and table of data are presented for the case when the lower half space is infinitely resistive.

On the probability of occurrences of thundery weather over Mohanbari aerodrome (North-east India)

SummaryEach month has been classified into six pentads and each day into four quarter-days; probable occurrences of thundery weather in each of these ones have been determined over Mohanbari aerodrome (North-east India). The duration of occurrences of thundery weather has been classified into five duration-groups and the probabilities that the thundery weather will belong to each of these groups have been calculated.ZusammenfassungEs wurden die Wahrscheinlichkeiten von Gewittern über dem Mohanbari-Flugplatz in Nordost-Indien für die sechs Pentaden jeden Monats und gesondert für die Tagesviertel bestimmt und die Andauer der Gewitter nach fünf Gruppen klassifiziert.

Computations of diabatic heating in the atmosphere

SummaryDiabatic heating of the atmosphere at 800, 600 and 400 mbar surfaces over India has been calculated, making use of thermodynamic and quasi-geostrophic omega equations. The numerically obtained distribution of the diabatic heating field is seen to be in agreement with the observed weather patterns in magnitude. The maximum value of diabatic heating is of the order of 4.0 to 4.5 cal gm−1 12 hr−1. Normally it ranges between 1.0 to 4.0 cal gm−1 12 hr−1. The vertical distribution of the absolute mean value of diabatic heating is seen to be at its maximum at about the 500 mbar surface.