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An attempt was made to statistically gauge the importance of moisture variability on convection initiation by analyzing data collected by radar, surface stations, soundings, and airborne in situ sensors over the 7 weeks of the International H2O Project (IHOP_2002). Based on radar refractivity data, the spatial structure of humidity near the surface proved to be very anisotropic, crosswind variability being typically twice as large as along-wind variability, in part as a result of the west-to-east climatological gradient in moisture across the Oklahoma panhandle. Variability in humidity was largest from the afternoon to sunset and smallest a few hours before and after sunrise. At the surface, variograms of refractivity increase almost linearly with scale in the crosswind direction, suggesting that the field of moisture shows little in terms of local maxima and minima. Higher in the boundary layer, moisture variability increases at small scales because of the entrainment of dry capping stable layer air as the daytime boundary layer grows, and the rate of that dry-air entrainment could be used to calculate surface moisture variability. The effect of the observed variability in moisture and temperature in the upper boundary layer on convective inhibition was quantified and contrasted with the effect expected from boundary layer updrafts. At synoptic scales and at the upper end of the mesoscale, the location of convection initiation is most sensitive to the variability in temperature. At smaller scales, storm development becomes extremely sensitive to the strength of updrafts; however, those same updrafts also magnify the effect of moisture and temperature variability, as a result of which the effect of small-scale moisture variability cannot be ignored. Some of the consequences of these findings on the representativeness of radiosonde measurements in the boundary layer and instrumentation needs for convection initiation forecasting are surveyed.

waste gasification processes based on thermal plasma (DC or AC plasma torches) at lab scale versus typical performances of waste autothermal gasification: LHV of the syngas, cold gas efficiency and net electrical efficiency. In the last part, a review has been done on the various torch technologies used for waste gasification by plasma at industrial scale, the major companies on this market and the perspectives of the industrial development of the waste gasification by thermal plasma. The main conclusions are that plasma technology is considered as a highly attractive route for the processing of waste-to-energy and can be easily adapted to the treatment of various wastes (municipal solid wastes, heavy oil, used car tires, medical wastes …). The high enthalpy, the residence time and high temperature in plasma can advantageously improve the conditions for gasification, which are inaccessible in other thermal processes and can allow reaching, due to low tar content in the syngas, better net electrical efficiency than autothermal processes.