Internal mechanism of metastable liquid water crystallization and its effects on intracloud processes
Internal mechanism of metastable liquid water crystallization and its effects on intracloud processes
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亚稳态液态水结晶的内部机制及其对云内过程的影响
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
A. N. Nevzorov
中科院分区：
文献类型：
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作者：
A. N. Nevzorov
普通过冷水和无定形水（A-水）的内部冻结（结晶）机制的具体功能被认为是。无定形水在凝结冰的形成中起着中间相的作用，并且能够以云滴的形式亚稳态存在。它表明，在通过结晶前，冰相采取的液相体积和过量的水质量是从前面分离的形式的自由分子，通过液体逃逸到气态介质。相变释放的能量被这些分子带走，因此形成的冰保持液体的初始温度。一个高速率的蒸汽流出的冻结滴产生（滴周围）的微尺度湍流区，这加速了云粒子和蒸汽之间的质量交换。由于云中水滴的冻结频率随其大小而增加，因此它们的冻结效应最初是随时间发展的。与此同时，这些效应引发了这样的过程，该过程以过冷水滴的完全蒸发和A水和冰粒的急剧增大而结束，即，在云中转变为这样的相混合状态，其中液体分散相由A-水滴组成。随着云的温度降低，云演化的初始（细分散）阶段的持续时间缩短，只能用由于水滴冻结而产生的微尺度扰动的发展来解释。
Specific features of an internal freezing (crystallization) mechanism for both ordinary supercooled water and amorphous water (A-water) are considered. Amorphous water plays the role of an intermediate phase in condensation ice formation and is capable of metastable existence in the form of cloud drops. It is demonstrated that, after passing the crystallization front, the ice phase takes the liquid-phase volume and the excessive water mass is detached from the front in the form of free molecules, which escape through the liquid into the gaseous medium. The released energy of the phase transition is removed with these molecules, so that the formed ice retains the initial temperature of the liquid. A high-rate vapor outflow from the freezing drop generates (around the drop) a zone of microscale turbulence, which accelerates the mass exchange between cloud particle and vapor. Since the freezing frequency of drops in a cloud increases with their size, the effects of their freezing develop initially in time. At the same time, these effects initiate such processes that end in a complete evaporation of supercooled water drops and in a sharp enlargement of A-water and ice particles, i.e., in cloud transition to such a phase-mixed state where the liquid disperse phase consists of A-water drops. A reduction in the duration of the initial (fine-dispersed) stage of the evolution of clouds with their temperature lowering can be explained only by the development of microscale disturbances as a result of the freezing of drops.