The horse, the cowboy and the lightning modeling: A case study on a farm in the State of Minas Gerais, Brazil
Lightning provoke fear, fright and many material and personal losses in the urban environment, corroborated by the agglomeration of people and concentration of high buildings. No less terrified, however, are the inhabitants of the countryside, including the animals, in the occurrences of atmospheric discharges. This article deals with the action of lightning that victimized a horse and a cowboy, on a farm, by simulating the propagation of potentials in the soil.
Assessing the dangers of lightning to livestock, a case study of a lightning event resulting in the deaths of 22 cattle
The majority of lightning fatalities occur in outdoor environments. The application of the IEC62305-2 lightning risk standard provides little insight into the risks to living beings in open spaces. The Median Lethal Limit (MLL) provides a means of describing the dangers to living beings in open spaces. A site in Mpumalanga, South Africa was investigated after a lightning incident resulted in the deaths of 22 cattle. The IEC62305-2 methodologies are used to assess the enclosure that housed the cattle. The same area is then assessed using the MLL and the results are compared. It is found that the MLL method in conjunction with the application of the rolling sphere provides a reasonable approximation for the danger of lightning to living beings in the enclosure. It is advised that some form of protection measures be installed to protect the cattle in the enclosure during a thunderstorm.
Control of the homopause level
Abstract This paper reviews the hypothesis that internal gravity wave breaking in the factor responsible for upper atmosphere turbulence generation and control of the number density at the homopause level. Available data from Mars and Earth support the hypothesis, originally introduced by Lindzen, that breaking thermal tides are responsible for the necessary turbulence. The lowest-order, equatorially trapped, westward-propagating diurnal tidal mode is the primary cause on the Earth, and lower-order westward-propagating semidiurnal modes are the primary cause on Mars. The frequencies and vertical wavenumbers of the responsible modes determine the eddy diffusion coefficients; energy density is only indirectly involved by determining which modes can break. A general scale relationship between tidal heating and velocity amplitude can be used to assess the breaking potential of tidal modes, and is used here as the basis for arguing that the number density at the Martian homopause is likely to have been stable over much of geologic time. Difficulties with this approach arise in the cases of Venus and Titan because of their peculiar zonal winds. For Jupiter and Saturn, internal gravity waves generated by nontidal mechanisms probably control the homopause.