1988 Fiscal Year Final Research Report Summary
Visualization of the diffusion field of water vapor around a growing snow crystal and its measurements.
| Project/Area Number |
61580051
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
結晶学
|
|---|
| Research Institution | Science University of Tokyo |
|---|
Principal Investigator |
GONDA Takehiko Faculty of Science and Technology, Science University of Tokyo, 理工学部, 助教授 (50084455)
|
|---|
| Project Period (FY) |
1986 – 1988
|
| Keywords | Snow crystal / Ice dendrite / Diffusion field / シュリーレン法 |
|---|
| Research Abstract |
A schlieren microscope was developed to visualze the diffusion field of water molecules around a dendritic ice crystal. This microscope is different the knife-edge method which was used by onuma et al, (1988), and can visualize the whole area of the diffusion field around the dendritic ice crystal by inserting a black spot at a back focal point of a schlieren lens in front of a growth cell. In the case of vapor growth, the diffusion field around the crystal could not be detected using the schlieren microscope built in this time, because the gradient of the refractive index around the crystal growing from vapor phase, the gradient of water vapor pressure around the crystal is small. However, the diffusion field around a dendritic ice crystal grown in sucrose solution could be easy detected. The effect of the diffusion field on the tip velocity and its shape of primary branches of the dendritic ice crystal was studied by varying the degree of supercooling of sucrose solution, visualizing the diffusion field of water molecules around the crystal growing from sucrose solution. As a result, it was found that the area of the diffusion field around a dendritic ice crystal decreased with increasing tip velocity or deceasing tip radius of the crystal. The area of the diffusion field around the crystal which was detected by the schlieren method corresponds with the area which the gradient of concentration of water molecules arise around the crystal. So, it was experimentaly clarified that the gradient of concentration of water molecules at the tip of an dendritic ice crystal increased with increasing tip velocity or decresing tip radius of the dendritic ice crystal. The same phenomenon can be applied to a snow crystal, an dendritic ice crystal from the vapor phase.
|
