Snow line

Schnee-flocke, /, snowflake. gips, m. snowy (foliated) gypsum, -glockcben, n. snowdrop, -grenze, /, snow line, -webe, /. snowdrift. schneeweisB, a. snow-white. 

A new reservoir of comets may have formed at around 5 AU in a local orbit around Jupiter or at least perturbed by its gravitational attraction. A comet close to Jupiter would simply have been captured, delivering its chemical payload to the ever-increasing gas giant. Some comets would merely have been deflected towards the inner terrestrial planets, delivering a similar payload of water and processed molecules. Cometary impacts such as the spectacular collision of the comet Shoemaker-Levy 9 with Jupiter would have been common in the early formation phase of the solar system but with a much greater collision rate. Calculations of the expected collision rate between the Earth and potential small comets deflected from the snow line may have been sufficient to provide the Earth with its entire... 

The short-orbit comet 67P has been influenced by two close encounters with the gravitational field of Jupiter in the same way as comets in the snow line may have been deflected during the formation of the Earth. Prior to 1840 its perihelion distance was 4.0 AU when the Jovian encounter reduced it to 3.0 AU or 450 million kilometres. It decreased steadily until a further brush with the Jovian gravitational field in 1959 knocked its perihelion distance to 1.29 AU, which is its present-day value. The properties of the comet are summarised in Table 6.5. 

Snow line The distance from the Sun at which water is stable on the surface of particles leading to comets. The presence of a large planetary mass such as Jupiter can then direct comets onto Earth, providing a source of cometary molecules to a prebiotic Earth... 

Snow line The distance from the Sun at which ice and snow can form on the surface of a meteorite or comet. 

A consequence of these changes is an increase of snow line with altitude and a decrease of days with snow cover. Even at altitudes around 1,500 m the models calculate a reduction of the amount of snowfall of about 20% up to the end of the twenty-first century. REMO [29] suggests that below 500 m snow could nearly disappear. 

During colder climates the snow lines were lower, in extreme cases by up to 1000m, as mentioned in section 13.8.3. This influenced... 

Comets are surviving members of a formerly vast distribution of solid bodies that formed in the cold regions of the solar nebula. Cometary bodies escaped incorporation into planets and ejection from the solar system and they have been stored in two distant reservoirs, the Oort cloud and the Kuiper Belt, for most of the age of the solar system. Observed comets appear to have formed between 5 AU and 55 AU. From a cosmochemical viewpoint, comets are particularly interesting bodies because they are preserved samples of the solar nebula s cold ice-bearing regions that occupied 99% of the areal extent of the solar nebula disk. All comets formed beyond the snow line of the nebula, where the conditions were... 

It may be predicted that, in the absence of physical stress of wind and snow blast, as in most tropical mountains below the snow line, the treeline should be highly dynamic within a long term temporal scale because trees are slow to establish, grow and mature. Thus, it is likely that other limitations to tree seed setting and growth are at play. One of these constraints is in fact seed germination in sites exposed to UV-B radiation (see section 5.3)... 

R.J. Exton, W.L. Snow Line shapes for satellites and inversion of the data to obtain interaction potentials. J. Quant. Spectrosc. Radiat. Transfer. 20, 1 (1978)... 

Abundance measurements of oxygen in Jupiter s atmosphere suggest that during its formation phase carbonaceous matter played a more important role than condensed ice. Therefore, Jupiter (and possibly Saturn) are found at the carbonaceous condensation/evaporation front (the tar line ) and the snow line was located farther out in the solar nebula (Lodders, 2004 [206]). This could also explain why Galileo probe measurements found much less water in Jupiter s atmosphere than expected. The snow line denotes the minimum radius from the Sun at which water ice could have condensed, at about 150 K, so it is the point in the solar nebula where water ice condenses. The tar line denotes the point where asphalt or tar-like material formed, pushing the snow line farther out in the solar nebula. 

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