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Ice
Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color. In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far away as the Oort cloud objects. Beyond the Solar System, it occurs as interstellar ice. It is abundant on Earth's surfaceparticularly in the polar regions and above the snow lineand, as a common form of precipitation and deposition, plays a key role in Earth's water cycle and climate. It falls as snowflakes and hail or occurs as frost, icicles or ice spikes and aggregates from snow as glaciers and ice sheets. Ice exhibits at least eighteen phases ( packing geometries), depending on temperature and pressure. When water is cooled rapidly (quenching), up to three types of amorphous ice can form depending on its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaciers
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions, but glaciers may be found in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand. Between latitudes 35°N and 35°S, glaciers occur only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Ih
Photograph showing details of an ice cube under magnification. Ice Ih is the form of ice commonly seen on Earth. Phase space of ice Ih with respect to other ice phases. Ice Ih (hexagonal ice crystal) (pronounced: ice one h, also known as ice-phase-one) is the hexagonal crystal form of ordinary ice, or frozen water. Virtually all ice in the biosphere is ice Ih, with the exception only of a small amount of ice Ic that is occasionally present in the upper atmosphere. Ice Ih exhibits many peculiar properties that are relevant to the existence of life and regulation of global climate. For a description of these properties, see ''Ice'', which deals primarily with ice Ih. The crystal structure is characterized by the oxygen atoms forming hexagonal symmetry with near tetrahedral bonding angles. Ice Ih is stable down to , as evidenced by x-ray diffraction and extremely high resolution thermal expansion measurements. Ice Ih is also stable under applied pressures of up to about where i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polar Ice Cap
A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land, but only that it must be a body of solid phase matter in the polar region. This causes the term "polar ice cap" to be something of a misnomer, as the term ice cap itself is applied more narrowly to bodies that are over land, and cover less than 50,000 km2: larger bodies are referred to as ice sheets. The composition of the ice will vary. For example, Earth's polar caps are mainly water ice, whereas Mars's polar ice caps are a mixture of solid carbon dioxide and water ice. Polar ice caps form because high-latitude regions receive less energy in the form of solar radiation from the Sun than equatorial regions, resulting in lower surface temperatures. Earth's polar caps have changed d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice VII
Ice VII is a cubic crystalline form of ice. It can be formed from liquid water above 3 GPa (30,000 atmospheres) by lowering its temperature to room temperature, or by decompressing heavy water (D2O) ice VI below 95 K. (Different types of ice, from ice II to ice XVIII, have been created in the laboratory at different temperatures and pressures. Ordinary water ice is known as ice Ih in the Bridgman nomenclature.) Ice VII is metastable over a wide range of temperatures and pressures and transforms into low-density amorphous ice (LDA) above . Ice VII has a triple point with liquid water and ice VI at 355 K and 2.216 GPa, with the melt line extending to at least and 10 GPa. Ice VII can be formed within nanoseconds by rapid compression via shock-waves. It can also be created by increasing the pressure on ice VI at ambient temperature. At around 5 GPa, Ice VII becomes the tetragonal Ice VIIt. Like the majority of ice phases (including ice Ih), the hydrogen atom positions are dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Ic
Ice Ic (pronounced "ice one c" or "ice I see") is a metastable cubic crystalline variant of ice. Hans König was the first to identify and deduce the structure of ice Ic. The oxygen atoms in ice Ic are arranged in a diamond structure; it is extremely similar to ice Ih having nearly identical densities and the same lattice constant along the hexagonal puckered-planes. It forms at temperatures between upon cooling, and can exist up to upon warming, when it transforms into ice Ih. Apart from forming from supercooled water, ice Ic has also been reported to form from amorphous ice as well as from the high-pressure ices II, III and V. It can form in and is occasionally present in the upper atmosphere and is believed to be responsible for the observation of Scheiner's halo, a rare ring that occurs near 28 degrees from the Sun or the Moon. Ordinary water ice is known as ice Ih (in the Bridgman nomenclature). Different types of ice, from ice II to ice XIX, have been created in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Spike
An ice spike is an ice formation, often in the shape of an inverted icicle, that projects upwards from the surface of a body of frozen water. Ice spikes created by natural processes on the surface of small bodies of frozen water have been reported for many decades, although their occurrence is quite rare. A mechanism for their formation, now known as the Bally–Dorsey model, was proposed in the early 20th century but this was not tested in the laboratory for many years. In recent years a number of photographs of natural ice spikes have appeared on the Internet as well as methods of producing them artificially by freezing distilled water in domestic refrigerators or freezers. This has allowed a small number of scientists to test the hypothesis in a laboratory setting and, although the experiments appear to confirm the validity of the Bally–Dorsey model, they have raised further questions about how natural ice spikes form, and more work remains to be done before the phe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Cycle
The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice, fresh water, saline water (salt water) and atmospheric water is variable depending on a wide range of climatic variables. The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, transpiration, condensation, precipitation, infiltration, surface runoff, and subsurface flow. In doing so, the water goes through different forms: liquid, solid (ice) and vapor. The ocean plays a key role in the water cycle as it is the source of 86% of global evaporation. The water cycle involves the exchange of energy, which leads to temperature changes. When water evaporates, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food, energy or organic micronutrients. Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is also the name of the liquid state of H2O at standard temperature and pressure. A number of natural states of water exist. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor. Water co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amorphous Ice
Amorphous ice (non-crystalline or "vitreous" ice) is an amorphous solid form of water. Common ice is a crystalline material wherein the molecules are regularly arranged in a hexagonal lattice, whereas amorphous ice has a lack of long-range order in its molecular arrangement. Amorphous ice is produced either by rapid cooling of liquid water (so the molecules do not have enough time to form a crystal lattice), or by compressing ordinary ice at low temperatures. Although almost all water ice on Earth is the familiar crystalline ice Ih, amorphous ice dominates in the depths of interstellar medium, making this likely the most common structure for H2O in the universe at large. Just as there are many different crystalline forms of ice (currently more than seventeen are known), there are also different forms of amorphous ice, distinguished principally by their densities. Formation The production of amorphous ice hinges on the fast rate of cooling. Liquid water must be cooled to its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interstellar Ice
Interstellar ice consists of grains of volatiles in the ice phase that form in the interstellar medium. Ice and dust grains form the primary material out of which the Solar System was formed. Grains of ice are found in the dense regions of molecular clouds, where new stars are formed. Temperatures in these regions can be as low as , allowing molecules that collide with grains to form an icy mantle. Thereafter, atoms undergo thermal motion across the surface, eventually forming bonds with other atoms. This results in the formation of water and methanol. Indeed, the ices are dominated by water and methanol, as well as ammonia, carbon monoxide and carbon dioxide. Frozen formaldehyde and molecular hydrogen may also be present. Found in lower abundances are nitriles, ketones, esters and carbonyl sulfide. The mantles of interstellar ice grains are generally amorphous, only becoming crystalline in the presence of a star. The composition of interstellar ice can be determined through its infr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury (planet)
Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman god ' ( Mercury), god of commerce, messenger of the gods, and mediator between gods and mortals, corresponding to the Greek god Hermes (). Like Venus, Mercury orbits the Sun within Earth's orbit as an inferior planet, and its apparent distance from the Sun as viewed from Earth never exceeds 28°. This proximity to the Sun means the planet can only be seen near the western horizon after sunset or the eastern horizon before sunrise, usually in twilight. At this time, it may appear as a bright star-like object, but is more difficult to observe than Venus. From Earth, the planet telescopically displays the complete range of phases, similar to Venus and the Moon, which recurs over its synodic period of approximately 116 days. The synodic proximity of Mercury to Earth makes Mercury most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor (reaching 100% relative humidity), so that the water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation but colloids, because the water vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called showers. Moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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