which is attributed to air trajectory effects. AngstrOm parameters, deduced from optical depth spectra, reveal a high value of o• (-0.9) for north of the ITCZ, while for the south oc is negative, indicating a change in the aerosol size distribution. Accumulation aerosols dominate in the north, while concentration of coarse aerosols remain nearly about the same, except very close to the coast. A north-south gradient in aerosol optical depth, with scaling distance of -1000 to 2000 km at shorter wavelengths and much higher at longer wavelengths, is observed. The gradient becomes shallower at high wind speeds. The large-scale dynamics associated with the movement of the ITCZ and its interannual variation appears to significantly influence the aerosol characteristics. As the southwest monsoon sets in over India, considerable wet removal and change in air mass characteristics cause a significant depletion in optical depths, which then became comparable to those prevailing in the southern hemisphere.

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Energy deposition by electrons having a Maxwellian energy distribution with characteristic energies 10, 30, and 100 keV, precipitating in the high-latitude upper atmosphere of Jupiter, has been studied using a continuous slowing down approximation. Electron fluxes, volume excitation, and ionization rates have been calculated. Chemical equilibrium equations have been solved for 24 ionic species using extensive hydrocarbon chemistry and incorporating diffusive transport for the ion H +. H2 Lyman and Werner bands and H Ly a intensities are obtained considering pure absorption in hydrocarbons. Comparison with Voyager ultraviolet spectrometer data requires incident energy fluxes of about 10, 18, and 45 ergs cm '2 s '1 for characteristic energies 10, 30, and 100 keY, respectively, for polar model methane abundance. Numerical experiments have been performed to study the effect of changing atomic hydrogen and methane number density, three-body reaction rates, incident energy flux, and H2(v_>4) vibrational temperature on plasma densities. Electrons with characteristic energy 30 key or somewhat higher give good overall agreement with Voyager 2 electron densities and also simulate the low-altitude peak measured by Pioneer 11. The calculated bremsstrahlung X ray flux is smaller by 1 to 2 orders of magnitude than the observed low-energy (<2 keY) X ray flux. New observations of high-energy (>2 keY) bremsstrahlung X ray emissions are required to give a definite resolution of the identity and energy of the particles responsible for the aurora on Jupiter.

Commercially available electric lamps are used in a laboratory experiment for the verification of Stefan’s law. Assuming that the emissivity of tungsten filament remains constant and that all the filament power goes out as radiation, Stefan’s T4 law can be verified from a log-log plot of radiated power P against temperature T of the filament. It is found that correction to filament power due to convection loss is necessary for the gas-filled lamps and not for vacuum lamps. The experimental value of the slope of the graph of log P vs log T for all these lamps is found to be 5, which shows that the emissivity of the filament surface is proportional to the temperature of the filament. A simplified laboratory experiment avoiding temperature calculations and convection loss corrections is described in this study.

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