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The distance from the die is called the height of the frost line. It depends on various factors, including the melt temperature, the speed of cooling, the extrusion speed, and the diameter of the bubble. The notion is important, since the higher the frost line, the more difficult to control the uniformity of the film thickness.
In astronomy or planetary science, the frost line, also known as the snow line or ice line, is the minimum distance from the central protostar of a solar nebula where the temperature is low enough for volatile compounds such as water, ammonia, methane, carbon dioxide and carbon monoxide to condense into solid grains, which will allow their accretion into planetesimals.
The frost depth depends on the climatic conditions of an area, the heat transfer properties of the soil and adjacent materials, and on nearby heat sources. For example, snow cover and asphalt insulate the ground and homes can heat the ground (see also heat island). The line varies by latitude, it is deeper closer to the poles.
In geology, the frost line is the level down to which the soil will normally freeze each winter. By an analogy, the term is introduced in other areas. Frost line (astrophysics), a particular distance in the solar nebula from the central protosun where it is cool enough for hydrogen compounds such as water, ammonia, and methane to condense into solid ice grains.
Black frost (or "killing frost") is not strictly speaking frost at all, because it is the condition seen in crops when the humidity is too low for frost to form, but the temperature falls so low that plant tissues freeze and die, becoming blackened, hence the term "black frost".
An artist's illustration giving a simple overview of the main regions of a protoplanetary disk, delineated by the soot and frost line, which for example has been observed around the star V883 Orionis. [15] The nebular hypothesis of solar system formation describes how protoplanetary disks are thought to evolve into planetary systems.
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A heavy coating of hoar frost, called white frost, is very similar in appearance to soft rime, but the formation process is different; it happens when there is no fog, but very high levels of air relative humidity (above 90%) and temperatures below −8 °C (18 °F). Soft rime formations appear as narrow white icy needles and scales.