Microtornadoes under a Nanocrystalline Igloo. 2. Results Predicting a Worldwide Intensification of Tornadoes
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- 作者：Andrei P. Sommer ; Dan Zhu
- 刊名：Crystal Growth & Design
- 出版年：2007
- 出版时间：December 2007
- 年：2007
- 卷：7
- 期：12
- 页码：2373 - 2375
- 全文大小：836K
- 年卷期：v.7,no.12(December 2007)
- ISSN：1528-7505
文摘
We recently documented the formation of microtornadoes in a nanocrystalline igloo grown in the laboratory. The igloo had 60 nm nanospheres as building blocks. The existence of the microtornadoes was derived from a vortical arrangement of nanospheres on the Petri dish forming the igloo base. A large body of parallels between the igloo-system and tornadic clouds attracted the interest of tornado researchers, who encouraged us to provide more details on the mechanism of formation of microtornadoes. Tornado research faces a turbulent period with an apparent intensification of tornadoes (in number and violence), but a lack of models that permit their reliable prediction in time. For this we focused on strategies to scale up our miniature igloo and to build larger systems, including nanocrystalline tents with a central stick. This involved the use of both larger drops and larger building blocks (200 nm nanospheres). Larger systems promised to facilitate further insight into details. To our surprise, systems built by 200 nm nanospheres tended to collapse. Therefore, we returned to think small and produced a second generation of nanocrystalline igloos based on 60 nm nanospheres, including ones with a diameter of 4 mm, twice the size of our first igloo. A closer inspection of the igloo compartments revealed a series of previously unrecognized details. Here we report the prevalence of congruent vortices on both sides of the system generating the microtornadoes: in the evaporation cooled igloo roof and on the warmer humid substrate beneath. This is the specific signature of one violently rotating column of humid air interconnecting igloo and substrate, an analogue to real tornadoes interconnecting a wall cloud with the ground.