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Attenuation by Hydrometeors Other than Rain
Published in Pranab Kumar Karmakar, Microwave Propagation and Remote Sensing: Atmospheric Influences with Models and Applications, 2017
The meteorological terminology of hail is mostly defined as ice particles with a diameter of 5 mm or more. Smaller particles are called ice pellets. Ice pellets are classified as sleet consisting of transparent and globular grains of ice. Hail is of the same type of sleet but, instead, it would be translucent. Sometimes larger hail has a diameter greater than 2 cm. Larger hail is formed only in well-developed cumulonimbus clouds when moisture is carried above about 30,000 ft. Smaller hail and soft hail are considered to be the essential features of all the thunderstorms. However, ice particles less than 1 cm diameter remain aloft in the core of the thunderstorm. These are likely to melt completely before reaching the ground. Therefore, although the occurrence of thunderstorm in tropics and subtropics are very frequent, hail is rarely found on the ground in tropics. Hailstorms are found to occur over mid latitude mountains and adjacent areas for 5 to 10 times in a year whereas the occurrence of thunderstorm is approximately 40 to 50 times in a year. Foster (1961) summarizes the physical properties of hail along with microphysics of hailstone growth in detail.
Novel techniques for cleaning surfaces contaminated with solid particles
Published in Aerosol Science and Technology, 2022
Sergey A. Grinshpun, Michael Yermakov, Xinyi Niu
Some existing surface decontamination approaches combine more than one principle. For example, one involves the high-pressure liquid nitrogen blasting and freezing of the deposited contaminants. This combination has a potential to improve the detachment of contaminants from the surface (Bonnell 2005; Reeves 2018; Rigby 2009a). Once released, the contaminants are removed by vacuuming and ventilation with air filtration. The risk of environmental contamination and over-pressurizing the cell are among the main shortcomings of this approach. The so-called wet ice blasting is also used in nuclear industry for surface decontamination. It is similar to the CO2 blasting in a way. In this method, the water ice pellets are utilized as an abrasive material. However, like in the high-pressure liquid nitrogen blasting, there is a notable risk of environmental contamination and over-pressurizing the cell (Reeves 2018).