DOI: 10.1039/C2CS35200A (Critical Review) Chem. Soc. Rev., 2012, 41, 6519-6554

Ice nucleation by particles immersed in supercooled cloud droplets

对流层云有两大类，其中存在冰：卷云和混合相类型。卷云在对流层上部形成，通常由液体溶液液滴形成，液滴可以均匀地冻结或通过涉及冰核的异质机制形成。^10-12虽然这些云是在气候方面重要的是，¹³运输的水蒸汽，^14,15和化学，¹⁶为这次审查，我们专注于混合相云。

混合相云存在于0°C至-37°C之间的温度，往往发生在对流层中低层，云对气候有重要影响，³并且是水文循环的组成部分。⁷这可能包括在非常不同的动态条件下形成的云，将在1.3节中详细讨论。混合相云的温度上限是由冰的融化在0℃下定义的，但是云尺寸水液滴能够在过冷状态持续至低于-37℃，在不存在能够催化形成冰颗粒。^7,17在存在正确类型的冰成核颗粒的情况下，这些云可以在0°C以下的任何温度下冰碛，但与CCN相比，这些颗粒往往很少见。这对云特性和[降水](javascript:popupOBO('CMO:0001688','c2cs35200a') "化学方法本体链接：降水")具有深远的意义。

1.2 Aerosol and ice nucleating particle concentrations

Aerosol concentrations vary substantially depending on location and season.^18–20 In general the aerosol concentration is lower in remote marine locations than continental regions, ranging from <10<small>²</small> cm<small>⁻³</small> in clean remote locations to >10<small>⁴</small> cm<small>⁻³</small> in urban locations and 10<small>²</small>–10<small>³</small> cm<small>⁻³</small> in the free troposphere.^18,19 Only a subset of these aerosol particles can serve as IN with typical IN concentrations ranging from 10<small>⁻⁴</small> to 10<small>⁻¹</small> cm<small>⁻³</small>,^7,21–24 with extreme values in excess of 1 cm<small>⁻³</small> within desert dust plumes.²⁵These measurements indicate that IN are rare in comparison to particles capable of serving as CCN. In an aircraft campaign Rogers et al.²³ reported that a fraction of 10<small>⁻³</small> to 10<small>⁻⁵</small> of the background aerosol served as IN; they also observed no correlation between IN and CCN concentrations. The fraction of aerosol serving as IN in marine air has been reported to be many orders of magnitude lower.²⁶ More recently it has been shown that in regions not influenced by sea salt aerosol, IN concentrations are correlated to the number of aerosol particles larger than 0.5 μm.²¹ In addition, observations show the number of particles capable of serving as IN increases dramatically with decreasing temperature.^7,22,27 In summary, only a small proportion of aerosol particles can serve as IN at all temperatures and considerable seasonal and spatial variability exists.

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云对冰核的数量明显敏感，但它们也对可用作CCN的气溶胶粒子数量以及CCN与IN的比率敏感

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