奇趣物理实验——翠羽明珠
2022-11-05 15:51阅读：
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文献1指出：
在河流湖泊中形成的冰块，其晶体取向大致可以分为如下5种情况。
Figure 2 is an example of an entire river ice profile as seen under
transmitted and polarized light. The superimposed ice layer is snow
ice, the primary layer is frozen frazil slush, and the secondary
layer is composed of columnar ice and frozen frazil slush.
The solid part of the continuous ice cover when viewed parallel to
the growth direction can be divided into three basic ice
layers.
a) Primary I
ce：The first type of ice of uniform structure and texture which
forms on a water body. On a calm surface the primary ice is an ice
skim which grows horizontally in the supercooled layer and is a few
tenths of a millimeter thick.
Calm Surface, Small Temperature Gradient：The grains are large to
extra large with irregularly shaped boundaries. The
crystallographic orientation of the c-axis is preferred
vertical.
Calm Surface, Large Temperature Gradient：The grain size is varied,
ranging from medium to extra large. The crystallization progresses
rapidly. The grain shape varies from tabular to needle-like and can
be several cm in length. Dendrites are also common. The
crystallographic orientation is random or vertically preferred
superimposed on a random orientation.
b) Secondary Ice：Secondary ice forms parallel to the heat flow
which in most cases is perpendicular to the primary ice. Its
structure is different from that of the primary ice and may be in
the form of columnar ice, the texture of which is entirely
controlled by the primary ice. Columnar Ice, Preferred Vertical
Orientation of c-Axis. The grains form parallel to the heat flow.
The grain size increases with depth, since un-favorably oriented
grains are consumed by those more favorably oriented. The
crystallographic orientation of the c-axis is preferred vertical
and remains so for the entire columnar ice depth. The grain size is
usually large to extra large; the grain shape is irregular. The
long axis of the grains depends on the relative orientation of
adjacent grains and can vary from equiaxed to a length equivalent
to the thickness of the columnar ice layer.
c) Superimposed Ice：Superimposed ice always forms on top of the
primary ice and is caused by flooding of the ice cover from any
imaginable water source. If there is snow on the ice surface, snow
ice may form.
文献2指出：
空气和氦气在冰块中气泡的形态，和结晶速率紧密相关。随着结晶速率的降低，气泡从椭圆形变为圆柱形，冰、水界面的形状逐渐变平。当结晶速率非常低时，可以得到透明的冰块。
Cylinders cease entirely at a growth rate of 3±1um/s, to give
completely clear ice.
Bubbles grow as cylinders below 5um/s, becoming egg shaped, the
narrow ends towards the freezing interface, at higher ice growth
velocities. Very high freezing rates give initially clear ice.
Subsequently, bubbles nucleate and grow at grain boundaries within
the ice. Bubbles do not move with re-crystallization, their spatial
distribution showing the grain boundary positions at the time of
nucleation.
Any air contained in clear ice was beyond the limit of detection of
their equipment. The distinction lay in the ability of smaller
atoms (helium, diameter 1.86 A, neon 2.4 A) to negotiate the
hexagonal channels of the ice lattice, diameter 2.4 A, compared
with the larger argon atom (diameter 3. I A). Similarly, according
to this model, it would not be expected that either oxygen or
nitrogen molecules, with narrow dimension 2.8 A and 3.0 A, would
dissolve.
As ice grows into supercooled water, air molecules too largeto fit
into the lattice are rejected and become concentrated in the liquid
near the interface to diffuse away towards regions of lower
concentration . As freezing progresses, the water at the interface
becomes supersaturated , eventually leading to the nucleation of
bubbles.
Significant metamorphosis of bubbles occurred after 10 h at - 10°
C, cylindrical bubbles becoming unstable and forming a line of
individual bubbles after 120 h.
Maeno and Kuroiwa observed air bubbles in snow crystals and found
that bubbles decreasedin size over the period of a few days and
small bubbles, a few micrometers in diameter, disappeared
completely. They attributed this to dissolution into defects in the
ice lattice, on the basis of the similarity of the observed
activation energies and those observed for other diffusion
processes.
当结晶速率非常高时（例如，让水滴撞击低温金属的表面），也可以得到透明冰块。但随着时间的延长，冰块内部会出现气泡。
文献3指出：
由于升华和凝华，当冰块两端存在温差时，气泡会向高温一端移动，移动速率和c轴取向无关。
When a temperature gradient is applied to bubbly ice, air bubbles
normally migrate slowly toward the warmer ice. This motion is
caused by sublimation from the warm wall and subsequent frost
deposition on the cold wall. the migration velocity is independent
of the angle between the c axis and the temperature gradient.
气泡在移动的过程中，外形会发生较大变化。
本次实验
使用直径6cm的球形冰块
是用网上买的硅胶磨具冻出来的
气泡较少
透明度较好
可以清晰的看到圆柱形气泡
根据文献2中写到
Cylinders cease entirely at a growth rate of 3±1um/s, to give
completely clear ice.
我的冰球生长速率约为0.8um/s(7cm/天)
但依然观察到少量柱状气泡
将冰球放在桌面上
自然光照射
自然融化
冰球中间显现白色
带有一圈黑色边框
正交偏振光的配置下
球形冰块的融化过程
比方形冰块更加迷人
像是黑色宇宙中背景下
孤独旋转的地球
这是冬天录制的实验
室内没有暖气
冰球融化时间超过2时
为了加速这一过程
我在右侧放了个小风扇
“吹”出了这个高挑的外形
冰球转动时
彩色条纹的宽度逐渐增加
色彩的饱和度逐渐下降
在这张图中
色彩饱和度的变化更为明显
彩色条纹最后消失
变为了暗淡的白色
平行偏振光的配置下
球形冰块的融化过程
冰球中有一串连贯的短圆柱气泡
像是断开的细长棍子
文献2中报道过圆柱气泡断裂的情况：
Significant metamorphosis of bubbles occurred after 10 h at - 10°
C, cylindrical bubbles becoming unstable and forming a line of
individual bubbles after 120 h.
有兴趣的读者，可以参阅如下文献，进行深入了解
1：Classification of river and lake ice. Canadian Geotechnical
Journal 8.1 (1971): 36-45.
2：Nucleation and growth of bubbles at an ice–water interface.
Journal of Glaciology 13.69 (1974): 489-520.
3：Migration of air bubbles in ice under a temperature gradient,
with application to “Snowball Earth”. Journal of Geophysical
Research: Atmospheres 115.D18 (2010).
