Of snow

Roofs are a basic element of shelter from inclement weather. Natural or hewn caves, including those of snow or ice, ate early evidence of human endeavors for protection from the cold, wind, rain, and sun. Nomadic people, before the benefits of agriculture had been discovered and housing schemes developed, depended on the availabiUty of natural materials to constmct shelters. Portable shelters, eg, tents, probably appeared early in history. Later, more permanent stmctures were developed from stone and brick. SaUent features depended strongly on the avadabihty of natural materials. The Babylonians used mud to form bricks and tiles that could be bonded with mortars or natural bitumen. Ancient buildings in Egypt were characterized by massive walls of stone and closely spaced columns that carried stone lintels to support a flat roof, often made of stone slabs. 

The filtrate and the washings contain in solution a small quantity of the product. This is recovered by distillation with steam. The acid distillate will consist of snow-white crystals (if it is protected from light) and a solution of the compound. The solid is removed by filtration and washed. The filtrate is made neutral with sodium carbonate and extracted with ether. Upon drying and evaporating the ethereal layer will yield mononitrothiophene contaminated with dinitrothiophene (Note 5),... 

Your facility is located in a semi-arid region of the United States which has an annual precipitation (including snowfall) of 12 inches of rain. (Snowfall should be converted to the equivalent inches of rain assume one foot of snow is equivalent to one inch of rain.) The area covered by your facility is 42 acres (about 170,000 square meters or 1,829,520 square feet). The area of your facility is 50 percent unimproved area, 10 percent asphaltic streets, and 40 percent concrete pavement. 

When the aldehyde is heated on the water-bath with 25 per cent, hydrochloric acid, it yields a triphenylmethane derivative, nonamethoxy-triphenylmethane, a body consisting of snow-white crystals, melting at 184 5°. The action of concentrated nitric acid upon the solution in glacial acetic acid of this triphenylmethane derivative gives rise to 1, 2, 5-trimethoxy-4-nitrobenzene (melting at 130°). With bromine, nonamethoxytriphenylmethane combines, with separation of a molecule of trimethoxy bromobenzene, into a tribromo additive compound of hexamethoxy diphenylmethane, a deep violet-blue body. The 1, 2, 5-tri-methoxy-4-bromobenzene (melting at 54 5°) may be obtained more readily from asaronic acid. 

Another family of feedbacks arises because the radical differences in the albedo (reflectivity) of ice, snow, and clouds compared to the rest of the planetary surface, which causes a loss of the absorption of solar radiation and thereby cools the planet. Indeed, the high albedo of snow and ice cover may be a factor that hastens the transition into ice ages once they have been initiated. Of course, the opposite holds due to decreasing albedo at the end of an ice age. As simple as this concept may appear to be, the cloud-albedo feedback is not easy to quantify because clouds reflect solar radiation (albedo effect) but absorb... 

It is very likely that the snow season will shorten in most of Europe. It is also very likely that the winter accumulation of snow will decrease. 

Wania F, Hoff JT, Jia CQ, et al. 1998. The effects of snow and ice on the environmental behaviour of hydrophobic organic chemicals. Environ Pollut 102 25-41. 

Pariasca, J.A.T. et al.. Effect of modified atmosphere packaging (MAP) and controlled atmosphere (CA) storage on the quality of snow pea pods (Pisum sativum L. var. saccharatum). Postharvest Biol. TechnoL, 21, 213, 2000. 

The main load to be considered in the design of these tanks is the hydrostatic pressure of the liquid, but the tanks must also be designed to withstand wind loading and, for some locations, the weight of snow on the tank roof. 

The operation of the snow cooling plant has so far been successful. During the year 2000—the first short cooling season—about 19,000 m3 of snow was sufficient to supply 93% of the cooling demand. In 2001 about 27,000 m3 of snow met 75% of the cooling demand. Some modifications were made on the storage as a result of experiences from the first two years of operation. 

There are two types of snow cooling system. One is direct heat exchanging system and the other is indirect heat exchanging system. Direct heat exchanging system is the same as the forced convection type. Room air is circulated between a room and a stored snow room by fans and cooled directly. The advantages of this system are... 

There are a number of suggested and implemented techniques of snow and ice storage for cooling applications. In Japan about 100 projects have been realized during the last 30 years, and in China there is about 50-100 snow and ice storage systems (Kobiyama, 2000). Also Canada, USA and Sweden have made efforts in the field. Below both realised and suggested techniques are presented. 

A number of different open pond snow and ice storage techniques have been suggested. In Ottawa a storage for 90,000 m3 of snow in an abandoned rock quarry (120 x 80 x 9.5 m3, L x W x H), was studied. The mean cooling load was 7,000 kW. A light colored PE plastic tarpaulin was suggested as insulation, with melt water re-circulation for cold extraction. The estimated payback time was 10 years (Morofsky, 1981). 

Naslund (2000) investigated a district cooling system in Sundsvall, mid Sweden, with sea water and stored snow. The cooling load was 7,900 kW and 7,450-8,560 MWh. Natural snow from streets and squares were complemented with artificial snow made by snow guns or water spraying. The estimated snow proportion was 43.6-66.8% and 122,500m3 of snow was needed. Two layers ofO.Ol mplastic sheets with thermal conductivity 0.04 W m-1 K-1 was recommended as insulation. The plant has not yet been realized (2005). 

A Japanese study investigated the possibility to use snow for atomic power plant cooling, to increase electricity production. With 38,400,000 tons of snow... 

In a similar Swedish project with snow cooling of a waste gas power plant 2,080,000 ton of snow would increase the annual electricity production 30.7 GWh. The snow should be stored in a 400 x 400 x 20 m3(Z x W x H) pond with water tight sides but open bottom. Here 0.2 m of wood chips was suggested as insulation (Falk et al., 2001). 

The simulations showed that 15,000 m3 of snow was not enough in any case. An un-insulated 30,000 m3 snow pile would be gone by mid-June and consequently the storage had to be thermally insulated. With 0.1 and 0.2 m of saw dust as thermal insulation the remaining snow volumes were 12,169 and 19,040 m3, Figure 202. 

Figure 202. Natural melting of 30,000 m3 of snow with 0.1 and 0.2 m of sawdust and without thermal insulation (from Nordell and Sundin, 1998)...

The political boundary conditions are connected with financial support, taxes and regulations and laws. For instance the Kyoto Protocol might be an incentive to an increased number of snow cooling plants, since they to a large extent uses renewable energy (Paksoy, 2003). 

Okajima, K., H. Nakagawa, S. Matsuda and T. Yamasita (1997). A cold storage for food using only natural energy, Proceedings of Snow Engineering Conference, Balkem, Rotterdam, Netherlands, pp. 569-572, ISBN 90-5410-865-7. 

Suzuki, T., S. Kobayashi, K. Tsushima, S. Shao, Y. Teng, and G. Liu, 1997. A case study on the utilization of snow and ice as natural cold energy source for low-temperature storage materials, Snow Engineering, pp. 553-558, ISBN 90 5410 865 7. 

The EPIC model is a comprehensive model that has been extensively tested for water balance estimates in dry and wet climates, including sites with significant accumulation of snow in winter.14... 

Shaved ice is used in place of crushed ice because of more efficient cooling. The use of snow is advised, if it is available. 

The dried product is then recrystallized from 30-35 ml. of a 1 3 mixture of boiling benzene and carbon tetrachloride (Note 7). The yield of snow-white crystals is 15-15.7 g. (82-86%) the recrystallized product melts at 131-132° and is sufficiently pure for synthetic purposes. A second recrystallization gives a product which melts at 132-133° (Notes 8 and 9). 

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