Ice structures, patterns, and processes: A view across the icefields

From the frontiers of research on ice dynamics in its broadest sense, this review surveys the structures of ice, the patterns or morphologies it may assume, and the physical and chemical processes in which it is involved. Open questions in the various fields of ice research in nature are highlighted, ranging from terrestrial and oceanic ice on Earth, to ice in the atmosphere, to ice on other Solar System bodies and in interstellar space.

Figure 1

The solid-liquid phase diagram of ice (the solid-liquid-gas triple point and liquid-gas coexistence line lie off the diagram to the left).

Figure 2

The local tetrahedral coordination of water molecules in ices. Each molecule accepts two hydrogen bonds from and donates two to its neighbors.

Figure 3

Rotational hydrogen-bond disorder in ices: the six possible orientations of a central water molecule and the hydrogen bonding consequences for its four neighbors.

Figure 4

Possible point defects in ice structures.

Figure 5

The three unit cell projections of the structure of ordered ice XIII; with 28 ${\mathrm{H}}_2\mathrm{O}$ molecules per unit cell it has the most complicated structure of all crystalline phases of ice.

Figure 6

Two-dimensional analogs of (a) crystalline and (b) amorphous “glassy” solids made up of threefold coordinated basic molecular units.

Figure 7

A thin 2 cm by 3.7 cm polycrystalline ice section seen under cross-polarized light. Individual crystals are seen in different shades and colors due to the birefringent nature of ice.

Figure 8

The vein-node network in polycrystalline ice: (a) Micrograph published originally by 333; (b) schematic from 409, modified from 501. Together they appear as Fig. 11 in 111.

Figure 9

Film morphologies. (a) A recent version of the structure zone model of solid film deposition (300); ice films produced in situ in a liquid-helium cooled ESEM apparatus in water-vapor deposition experiments (75): (b) zone 1, cauliflower morphology; (c) zone T, transition morphology; (d) zone M, matchstick morphology.

Figure 10

Transmission IR spectra of mixtures of ${\mathrm{CO}}_2$ and water in the region of the ${\nu }_3$ band of ${\mathrm{CO}}_2$. Left: spectra of two samples obtained by sequential deposition of water and ${\mathrm{CO}}_2$ (above) and simultaneous deposition (below) of the vapors at 80 K. After warming the sample, most ${\mathrm{CO}}_2$-norm has sublimated and ${\mathrm{CO}}_2$-dist is better appreciated. From 164. Right: spectrum focused on the same band for the ${}^{13}\mathrm{CO}_2$ isotopomer. The two ${\mathrm{CO}}_2$ structures are characterized by a band deconvolution analysis. From 222.

Figure 11

A schematic diagram of Earth’s atmospheric stratigraphy, depicting the locations of icy cloud layers.

Figure 12

Laboratory models sorted by their proximity to the atmospheric reality and the accessibility of physicochemical parameters: (a) aerosol chamber AIDA built for ice nucleation experiments; (b) aerosol laminar flow tube; (c) electrodynamic balance with levitated ice particle; (d) cryochamber with Peltier element suited for light-microscopic observation of the freezing of water droplets in an oil emulsion; (e) ESEM with cryostage and cryotransfer chamber; and (f) UHV cryostat working at 6 K suited to isolate transient species in rare gas matrices.

Figure 13

Nitric acid solvation by water molecules: (a), (b) ${\mathrm{HNO}}_3({\mathrm{H}}_2\mathrm{O}{)}_6$ clusters in two different configurations and (c) a crystalline cubic ice slab with one ${\mathrm{HNO}}_3$ in the $x\mathrm{\text{−}}z$ direction.

Figure 14

The Nakaya diagram (398) showing snowflake morphology as a function of supersaturation and temperature. From 315.

Figure 15

Penitentes tens of centimeters long tilt toward the predominant direction of solar radiation.

Figure 16

Schematic cross section of how snow transforms via firn into ice to create glaciers and ice sheets.

Figure 17

Illustration of individual uptake processes.

Figure 18

Comparison of breakthrough curves observed for nitrous acid (HONO; solid black line) and for acetic acid (${\mathrm{CH}}_3\mathrm{COOH}$; dashed gray line). A packed ice bed flow tube at 243 K was exposed to the trace gases at $t=0$. For the nitrous acid case, the ice was bypassed at $t=1\times {10}^4\mathrm{s}$. The acetic acid recovered back to its initial concentration before the ice was bypassed, while the nitrous acid trace shows a long-lasting tail. The dash-dotted line represents the result of an asymptotic fit made to retrieve the diffusion parameters that describe the shape of the tail. From 260.

Figure 19

Lidar image of sea-ice topography in the Baltic Sea. The width of the swath is 400 m. Colors and shades indicate a freeboard of ice (height of the surface relative to the ocean surface) in centimeters.

Figure 20

Conceptual sketches illustrating the life cycle of pack ice by means of the ice-thickness distribution function $g(h)$. (a) The initial freezing of the ocean and the thermodynamical growth of sea ice; (b)  $g(h)$ after large-scale fracturing; and (c) the redistribution of pack ice. (d) The observed distribution of sea-ice draft in the Canada basin in spring during two different climatological periods (solid line: 1975–1987, dashed line: 1988–2000). From 416.

Figure 21

Pancake and frazil ice in the Weddell Sea. Pancake thickness here was 5–8 cm and their diameters around 1 m. The image shows the operation of taking samples of frazil ice between the pancake floes.

Figure 22

$385\times 385\mathrm{km}$ satellite (MODIS) image of pack ice in the Lincoln Sea.

Figure 23

Finger rafting in the Lincoln Sea; the fingers are approximately 10–30 m in length.

Figure 24

Membranes and vesicles in ice: (a) Phosphatidylcholines distributed in sea water form membranes on ice surfaces and at the edges of mineral particles. (b) Formation of vesicles in sea ice by phosphatidylcholines during partial melting. (c) Peptide clusters of phenylalanine form vesicles in the ice. (d) Yeast RNA dissolved in sea water and frozen in sea ice forms vesicles under the influence of ultraviolet light.

Figure 25

Proposed life-promoting reactions in sea ice: Simple prebiotic organic compounds were transported from sea water into the body of the ice (typical thickness 1–2 m); in the icy medium the reagents were sorted, separated, and concentrated; chemical reactions led to polypeptides, RNA structures, and membranes; the membranes formed vesicles embedding biomolecules such as RNA and others; and finally the vesicles left the ice and floated into the sea water beneath. From 557.