Have you always wondered how a dendritic structure is growing? And once it is developed how it further grows when falling through different growth regime towards the ground? We wondered the same thing. So enjoy these videos we took in the cold chamber of the University of Mainz of dendrites changing their morphology. Each image corresponds to 10 seconds growth time, so while the videos are spead up, you can literally watch the structures grow in real time as well! If you want to know details about the research ideas behind the videos, have a look at our poster for the 5th International Summer Snowfall Workshop.
A dendrite in the needle regime
This video shows the growth of dendrites on a 100 micrometer thick nylon string. The dendritic structures were first grown at temperatures between -12 to -17°C, the temperature region where plate-like and more specifically dendritic structures are expected to grow. We then let the cold chamber warm up, in order to change from the plate-like growth regime to a columnar growth regime, which can be found at temperatures between -10°C and -5°C. We then let the structures further grow for roughly 20 minutes. It is very interesting to see the structure of the delicate dendritic arms changing, when exposed to the columnar growth regime. In microscope images (not shown) and also in the third video, you can see that columnar structures are growing on each tiny dendritic branch, effectively reducing the space between the arms and changing the morphology of the particle.
A second dendrite in the needle regime
As in the first video, here you can see the growth of dendrites on a 100 micrometer thick nylon string. Similarly, the dendritic structures were first grown at temperatures between -12 to -17°C. Then, the chamber was again allowed to warm to temperatures around -7°C to have columnar particles growing on the dendritic arms. Again in this experiment, the resulting structures have similar features as in the experiment above, with columnar structures are growing on each tiny dendritic branch, effectively reducing the space between the arms and changing the morphology of the particle. For this video, also microscope images are available, have a look at our poster:
A dendrite that was in the needle regime and gets lifted back into its habitat
In this video you can see the next step, here a dendrite was grown at -15°C, then brought into the regime around -7°C, growing columnar structures on each arm of the dendrite. These are the structures visible in the video. We then decided to cool the chamber down again to see what happens to the particle. Interestingly, the change into the plate-like growth regime results in plate-like structures growing on the tips of each column. This behaviour has already been observed by many studies, when a columnar particle falls into the plate-like growth regime. Nevertheless, it is fascinating to observe!
