Components of atmosphere Essay Example for Free

Components of atmosphere Essay The main components of atmosphere are almost invariant. However, the content of water vapor is an exception that it varies with the changing of location, season and time. Oxygen and water vapor plays a significant role on the processes of atmospheric corrosion. Therefore, atmospheric corrosion can be classified in the following three categories: Dry corrosion Damp corrosion Wet corrosion Component Percent/% Component Percent/% Component Percent/% Atmosphere 100 H2O. Components of atmosphere (Impurity excluded, 10? ) 2. 1 Dry corrosion In the absence of significant water vapor, many common metals develop films of oxide. In the presence of traces of gaseous pollutants, copper, silver and other non-ferrous metals undergo film formation which is known as tarnishing. The tarnishing of silver in air is well-known. Tarnishing by hydrogen sulfide may be retarded by moisture if present in very small amounts. 2. 2 Damp Corrosion Damp corrosion would occur only when the relative humidity reaches 70% which is considered generally as the critical value for the onset of corrosion. The precise level of critical humidity varies with the type of contaminants, such as dust and salt particles, and the composition of metals. For instance, in the presence of marine salts corrosion is stimulated at lower values of relative humidity. The difference between the damp and wet environment is very narrow and it is more representative of a climatic condition rather than the magnitude of corrosion. Damp environments promote the corrosion of most metals. Water saturated with dissolved gases, such as CO2, H2S and SO2, cause severe corrosion of iron and steels, copper, nickel, silver and other non-metallic materials and alloys. For example, silver loses its luster and develops a tarnished film of sulfide on coming in contact with H2S, and copper develops tints and becomes black. In agricultural areas abundance of ammonia, particularly during the rainy seasons, subjects copper fittings to seasonal cracking and causes serious damage to water distribution systems. 2. 3 Wet Corrosion This is the most frequently observed form of atmospheric corrosion, where the water layers or pockets are formed on the metal surface, and the metal surface remains constantly in contact with water. The rate of corrosion would depend on the solubility of the corrosion product. Higher solubility means a higher rate of corrosion, because the dissolved ions increase the electrolytic conductivity. In case of alternate dry and wet conditions, the dry corrosion product film may absorb moisture from the air which increases the rate of corrosion of the metal by bringing the moisture in contact with the metal surface. Patina formation on copper, such as brochantite, and corrosion of iron and steel structures are common examples of corrosion caused by wet atmosphere.

Stonehenge :: European Europe History

Stonehenge Stonehenge, one of the great Seven Wonders of the World, but what do we really know about it. What was its purpose, how was it built and by whom. Many different answers come up when asking the question "What was the purpose of Stonehenge", some say that it was a horrid place, which the Druids used for religious sacrifice, but most others have a more positive idea. A temple of the sun, a Pagan Cathedral, or a holy sanctuary in the midst of blessed ground, or maybe a clock or even a place to Predict Eclipses. No one really knows what it was used for; this is due to a great number of facts surrounding all of these ideas. Many ideas come up when talking about why this great structure was built along with an equal amount on who built it. The Druids is the most common response because the Druids inhabited most of the area in which Stonehenge is built. The Pagans are another common answer to this age old question because of the building structure of Stonehenge how it resembles a Pagan Cathe dral. Whoever built Stonehenge, they were an extremely advanced society either on purpose or by complete fluke. Many say that because of Stonehenge's exact solar and lunar alignment. That is was the most common thought is that it was built to predict eclipses for worshiping. The following essay is going to state the facts and myths about the great Stonehenge. By the end of this essay, hopefully a solid conclusion will be found to be the most plausible answer for Stonehenges construction. The moon, it has been a sight for all over time. Back long ago little was none of the reasons for an eclipses, it was thought to be a sing from the gods. In a society which worshiped gods for all the mysteries of the world, the eclipse must have been very special. The builders of Stonehenge must have been marveled at the sight of this holy event, which happened every four years. Most likely the great Stonehenge was built to be a prediction device for the eclipse. Many people have studied Stonehenge and many have found that the stones are mathematically placed to show when and eclipse might occur. "In favor of this solution - that the Aubrey holes were used as a computer are these facts: the number 56 is the smallest number that measures the swing of the moon with an over-all accuracy of better than 3 days, and lunar cycles provide the only method of long-range eclipse prediction related to the seasons of the year.

Compare and Contrast Between the Socs and Greasers

Compare and Contrast Essay Have you ever thought once that the Greasers and Socs (from â€Å"The Outsiders†) could ever have similarities? These rich kids and deprived kids will ever have something in common. Well, you’re going to find out each ones life style, personality and society treatment. How each of them lives, how they are treated by the society and how they both feel. The Socs are filthy rich kids in the west side, making them very spoiled and all their orders are brought and done. To give an example to that is Bob Sheldon, and his gang ride with a mustang, for teenage kid this is very expensive.While, the Greasers are a group of underprivileged children who have some that work for their living, but still don’t get half of what the Socs get. Most of them have very long and greasy hair because they couldn’t afford to shave. Which shows huge difference in lifestyle. Secondly, here comes their general personality, starting with Socs. To keep up in t heir life they have to lock their emotions up inside until they are numb to their effects. They remember the feeling of anger the hit the weak ones in the society; the Greasers.They jump on the Greasers and just start hitting them and terrorizing them. Unlike the Socs, the Greasers are too emotional, they take everything serious. And when they try express it they get into serious trouble, it is why dally got arrested a over half a dozen times. Have in consideration that they both are starting to get sick of their lives and how each lives it. For example Cherry is bored of pretending not being how she is for her friends and so is Ponyboy, he pretends to be not in love with literature and music in front of his family and friends not feel weird our his friends.Here will be discussed how society treats both crews of characters. The Greasers were always known as vicious thugs in the neighborhood while they are just misunderstood kids in the wrong place and also with know one to tell them what to do. On the other hand the Socs. have to live up to a perfect vision people see of them, they have to stand up others people high expectations, Which really kills them in the inside. It reminds me when Cherry was in the movie theatre talking with Ponyboy, she didn’t hide loving bizarre music nor reading literature.She told her friends that at all, as she is a cheerleader. Finally, after comparing and contrasting Greasers and the Socs we conclude that both the Socs and the Greasers have completely different lifestyles. Surprisingly, they have something in common; not being who they are with their closest friends and also are not penchant to be judged. It shows us no mater how wealthy or poor you are you still are a normal person like everyone else, no difference in having feelings.

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