[en] The detailed behaviour of the sea level in the Gulf of Trieste, in the presence of a sharp wind impulse at the first hours on 25th September 1987, is described. For the first time the data have been obtained by means of an ultrasound tide gauge, with a digital record and one minute scanning

[en] The occurrence of a springtime ozone depletion over antarctica appears to be the result of a chain of processes leading to catalitic destruction of the gas by the action of halogene radicals, in particular chlorine oxide. High abundances of ClO in the stratosphere are determined by abnormally low concentration of nitrogen compounds; such denitrification is likely to be caused by heterogeneous reactions and transport carried out by the clouds present in the polar stratosphere. Stratospheric clouds form during most of the winter and the beginning of spring over the polar regions. Due to scarce accessibility, knowledge of their properties is still poor. Information on extent, particle shape and size distributions is, however, fundamental for the understanding of the magnitude of their contribution to the destruction chain. A ballon-borne experiment, aimed at the in situ observation of cloud particles from 2 to 200 microns in radius, is presented. This would be the first system to provide on-line TV images of cloud particles. The first measurement campaign in antarctica is planned for the period august-october 1990

[en] Water tank experiments were conducted to investigate plume rise and diffusion of gases discharged from stacks under calm conditions with field wind velocity less than 0.4 m/s with stable thermal stratification. Similarity rules of scaled model experiments were obtained from nondimensional analysis of the fundamental equation. The densimetric Froude number of a plume and the buoyancy ratio of the plume and the atmosphere were varied during the water tank experiments while plume rise height, plume thickness, etc. were measured. It was found that the experimental results could be expressed in terms of these two dimensionless parameters

[en] In a recent paper, Petroni et al. claim that a necessary condition for the instability of the two-dimensional steady flows is a 'double cascade' of energy and enstrophy respectively to larger and to smaller scales of motion. It is shown here that the analytical reasoning employed by Petroni et al. is flawed and that their conclusions are incorrect. What is true is that in any scale interaction (whether an instability or not), neither energy nor enstrophy can be transferred in one spectral direction only, but this result is extremely well known

[en] In the last few years systematic investigations concerning electromagnetic precursors of earthquakes have been carried out by many authors. The studies regarding the electric component of electromagnetic emissions are made with surface or underground equipments. An electromagnetic-emission monitoring system suitable for underground deployment has been made at the Physic Departement of the ''La Sapienza'' University of Rome. The system is able to detect electric signals with an amplitude up to about 100 mV and a frequency band that lies between 0.3 and 300 Hz

[en] A variety of quasi-geostrophic equations can be developed to obtain, in the oceanographic case, conservation principles consistently referred to bounded basins. Some unsatisfactory examples found in the literature are critically revisited

[en] By applying a perturbation technique to the Euler equation for a two-layer fluid is shown that the evolution of the interface is described by a Kortweg-de Vries equation. This model is applied to describe the tide generation of internal waves in the Straits of Gibraltar

[en] The micrometeorological project (MICMET), aimed at building a network of meteorological station in the region of Friuli-Venezia Giulia, has been started. A description of the preliminary measuring equipment and the projected time schedule for the overall completion of the plan is given. Some details of the data-collecting system together with the first analysis of data are also reported

[en] The time response of a anisotropic, inhomogeneus magnetized plasma to a time-dependent externally applied electric field is studied. The plasma is considered as a conducting medium embedded in a static magnetic field B₀. The driving term E₀ is assumed to be normal to the ambient magnetic field, with a space dependence only in the (E₀, B₀)-plane (two-dimensional case). The problem is treated as an initial (in time) and boundary (in space) value problem, and an analytic solution is obtained for the time response of the system to a unit step of electric field

[en] Starting from three-hourly measurements, carried out for periods from 5 to 30 years in 135 Italian sites, analytical functions were computed, describing persistencies of wind calm and of winds with intensity higher than any pre-fixed threshold. On the basis of the results obtained, the Italian areas were pointed out, where wind calm and higher-intensity wind are more persistent. Further, an estimation of the feasibility limits was carried out from the results obtained, with respect to the period of measurement analysed