Determination of Ice Crystal Growth Parameters in a Supercooled Cloud Tunnel.
Determination of Ice Crystal Growth Parameters in a Supercooled Cloud Tunnel.
复制标题
过冷云隧道中冰晶生长参数的测定。
DOI：
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发表时间：
1981
期刊：
影响因子：
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通讯作者：
Mike Wayne Kowa
中科院分区：
文献类型：
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作者：
Mike Wayne Kowa
摘要：为了全面了解动态变化的冰晶在穿过过冷云时的行为，需要同时测定冰晶的大小、质量、表观密度和下落速度。在前两次冰晶生长研究经验的基础上，发展了一种新的过冷云隧道。它成功地展示了在自然过冷云中精确模拟自由落体条件下晶体生长的能力。隧道工作/观测部分的新垂直会聚设计允许冰晶稳定地悬浮在过冷的云层气流中无限期。采用一种新的雾室，使过冷雾在进入工作/观测段之前，液滴数量、浓度和温度均一化。提出了一种控制和保持过冷雾中水分含量不变的方法。通过工作/观察部分的流量由专门设计的阀门控制，该阀门还将进入腔室的总流量保持在恒定的水平。这种配置使过冷雾在整个实验运行过程中保持恒定。设计了一种特殊的方法来保存收集到的冰晶，这样就可以从顶部和侧面拍摄它们。这种方法还可以通过熔融来准确测定晶体质量。流动速度，因此晶体下落速度，是由电子压力计连续测量，而热电偶则持续记录过冷雾温度。
Abstract : In order to completely understand the behavior of a dynamically changing ice crystal as it falls through a supercooled cloud, the simultaneous determination of the crystal size, mass, apparent density, and fall velocity is desirable. Based on the experience obtained in our two previous ice crystal growth studies, a new supercooled cloud tunnel has been developed. It has successfully demonstrated the capability of accurately simulating the crystal growth under free-fall conditions in a natural supercooled cloud. The new vertically converging design for the working/observation section of the tunnel permits ice crystals to be stably suspended in a supercooled cloud airstream for indefinite lengths of time. A new fog chamber is used to make the supercooled fog homogeneous with respect to droplet number and concentration, and temperature, before entering the working/observation section. A method has been developed by which the moisture content in the supercooled fog can be controlled and held constant. The flow rate through the working/observation section is controlled by a specially designed valve which also maintains the total flow into the chamber at a constant level. This configuration keeps the supercooled fog condition constant throughout an experimental run. A special method is devised to preserve the collected ice crystals so they can be photographed from both the top and side. This method also allows for accurate crystal mass determination by melting. The flow velocity, and therefore crystal fall velocity, is continually measured by an electronic manometer while a thermocouple continually records the supercooled fog temperature.