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Atmosphere Fundamentals
Published in N. Blaunstein, N. Kopeika, Optical Waves and Laser Beams in the Irregular Atmosphere, 2017
Nathan Blaunstein, Natan Kopeika
Snow is the solid form of water that crystallizes in the atmosphere and, falling to the Earth, covers permanently or temporarily about 23% of the Earth's surface. Snow falls at sea level poleward of latitude 35°N and 35°S, though on the west coast of continents it generally falls only at higher latitudes. Close to the equator, snowfall occurs exclusively in mountain regions, at elevations of 4900 m or higher. The size and shape of the crystals depend mainly on the temperature and the amount of water vapor available as they develop. In colder and drier air, the particles remain smaller and compact. Frozen precipitation has been classified into seven forms of snow crystals and three types of particles: graupel, that is, granular snow pellets, also called soft hail, sleet, that is, partly frozen ice pellets, and hail, for example, hard spheres of ice (see details in References 1–4, 6–9).
Corrosion rate prediction and influencing factors evaluation of low-alloy steels in marine atmosphere using machine learning approach
Published in Science and Technology of Advanced Materials, 2020
Luchun Yan, Yupeng Diao, Zhaoyang Lang, Kewei Gao
During the whole exposure periods (Figure 3), the total content of alloying elements (ELEMENTS) was always one of the most significant features. Meanwhile, as shown in Figure 3b,d and f, the chloride deposition rate (CHLORIDE) and precipitation (PRECIPIT) had the most significant effect on the corrosion rate in the first three years of exposure test. In the initial formation stage of the rust layer, the corrosion product film was loose and thin. The deposited chloride increased the concentration of corrosive ions, and the precipitation (in the forms of drizzle, rain, sleet, snow, graupel and hail) easily penetrated through the rust layer and created a wet corrosive environment on the metal surface. In more than five years of exposure tests, the RH_MIN became the most significant environmental factor (Figure 3(h,j,l)). As a thick and dense rust layer had been formed on the surface of the specimen, its permeability had changed significantly [46]. It became difficult for both the chloride ions and raindrops to reach the metal surface by permeating the rust layer. However, the long-term high relative humidity would affect the water content in the rust layer and help to form a corrosive microenvironment on the metal surface [45]. For instance, Ma et al. [47] proved that the existence of the outer layer makes the time of wet longer in the rust/steel interface, which provides a suitable location for electrochemical reactions, thereby inducing incessant corrosion and poor weatherability.
Comparison of two double-moment microphysics schemes in aspects of warm-rain droplet spectra and raindrop budget
Published in Atmospheric and Oceanic Science Letters, 2019
Hengchi LEI, Jiaxu GUO, Di CHEN, Jiefan YANG
The rain mixing ratio is mainly increased by rain-collecting cloud droplets (Accretion-Cloud in Figure 6) and Melt_sg, and decreased by falling to the ground (Sedimentation in Figure 6). In domain A, rain-cloud collection is comparable with Melt_sg, while Melt_sg is the dominant source of the rain mixing ratio in domain B in both schemes. Evaporation of raindrops is vigorous in domain B, especially in the WDM6 scheme. Autoconversion is an important source of the RNC, while it contributes little to the rain mixing ratio, indicating that the raindrop size produced by autoconversion is much smaller than that produced by Melt_sg. The term Accretion-c&mix in the WDM6 scheme represents the process of clouds collected by snow and graupel in a warm area converting to rain, which could be considered another form of Melt_sg.
Hail suppression effectiveness for different cloud condensation nucleus (CCN) populations in continental and maritime environments
Published in Aerosol Science and Technology, 2023
In the cloud model, all liquid drops (cloud water and rainwater) used a unified Khrgian-Mazin size distribution (Pruppacher and Klett 1997; Kovačević and Ćurić 2013). The minimum and maximum values of hydrometeor size were provided by Kovačević and Ćurić (2014). Cloud ice crystals were distributed in gamma function form (Hu and He 1988). Ice-precipitating elements (snow, graupel, frozen raindrops, and hail) used an exponential distribution (Lin, Farley, and Orville 1983).