Berikut ini Rangkuman Materi Ujian Semester Kls XII selamat belajar and semoga
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Thunderstorm, also known as an electrical storm or a lightning storm, is a form of weather characterized by the presence of lightning and its effect: thunder. It is usually accompanied by heavy rain and sometimes snow, hail, or no precipitation at all. Thunderstorms may line up in a series, and strong or severe thunderstorms may rotate.
Warm air has a lower density than cool air, so warm air rises within cooler air, similar to hot air balloons. Clouds form as warm air carrying moisture rises within cooler air. As the warm air rises, it cools. The moist water vapor begins to condense. When the moisture condenses, this releases energy that keeps the air warmer than its surroundings, so that it continues to rise. If enough instability is present in the atmosphere, this process will continue long enough for cumulonimbus clouds to form, which support lightning and thunder.
All thunderstorms, regardless of type, go through three stages: the cumulus stage, the mature stage, and the dissipation stage. Depending on the conditions present in the atmosphere, these three stages can take anywhere from 20 minutes to several hours to occur.
The first stage of a thunderstorm is the cumulus stage, or developing stage. In this stage, masses of moisture are lifted upwards into the atmosphere. The trigger for this lift can be insolation heating the ground producing thermals, areas where two winds converge forcing air upwards, or where winds blow over terrain of increasing elevation. The moisture rapidly cools into liquid drops of water, which appears as cumulus clouds. As the water vapor condenses into liquid, latent heat is released which warms the air, causing it to become less dense than the surrounding dry air. The air tends to rise in an updraft through the process of convection (hence the term convective precipitation). This creates a low-pressure zone beneath the forming thunderstorm. In a typical thunderstorm, approximately 5×108 kg of water vapor are lifted, and the amount of energy released when this condenses is about equal to the energy used by a city (US-2002) of 100,000 during a month.
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The Magic Box
Once upon a time there was a poor farmer who lived with his wife. One day he dug up his field and found a big box. He took it home with him and showed it to his wife. His wife cleaned the box and kept it in their house.
One sunny morning his wife dropped an apple into it. Suddenly the box began fill up with apples. No matter how many the apples were taken out. More apples took their place. So the farmer and his wife decide to sell the apples and in short time they were able to live quite comfortably.
One day, the farmer dropped a gold coin into the box. At once, apples disappeared and the box began to fill itself with coins. Every day the farmer and his wife collected hundreds of gold coins from the box. Soon, they became very rich.
Having heard that his son had gone rich, the farmer’s father visited the couple. He was not very strong and he could not go out to work anymore. So the farmer asked the old man to help him to take the money out of the box. When his father told his son that he was tired and wanted to have a rest, the farmer shouted at him, “why are you so lazy? Why can’t you work harder?”
The old man didn’t say anything, and continued to work until he fell into the box and suddenly died. At once, the money disappeared and the box began to fill up with dead fathers.
The farmer had to pull them out and bury them. To do this, he had to spend all the money he had collected. When he had used up all the money, the box broke and the farmer was just as poor as he was before.
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Whales are sea-living mammals. They therefore breathe air but cannot survive on land. Some species are very large indeed and the blue whale, which can exceed 30 m in length, is the largest animal to have lived on earth. Superficially, the whale looks rather like a fish, but there are important differences in its external structure: its tail sonsists of a pair of broad, flat, horizontal paddles. The tail of a fish is vertical, and it has a single nostril on top of its large, broad head. The skin is smooth and shiny and beneath it lies a layer of fat (blubber). This is up to 30 cm in thickness and serves to conserve heat and body fluids.
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Soal Essay !
Sequence of Logical Reasons
Sequence of Logical Reasons
Sequence of Logical Reasons
HOW DESERTS REMAIN DRY
These are three possible reasons why deserts remain dry. These are high mountain barrier, cold ocean currents and high pressure systems.
When warm air passes over the ocean it picks up moisture in the form of water vapour. As this moist air travels over mountain ranges. When begins to rise, the air cools and this causes the water vapour to condense into droplets which fall as rain. When the air reaches the other side of the mountain barrier, it has lost all its moisture and so the other side of the mountain remains dry.
Cold Ocean Currents
Air passing over cold ocean currents is cooled and therefore is unable to pick up and hold much moisture. When this cold air mass reaches the warm desert, any moisture in the air is evaporated and so does not fall as rain and so the desert remains dry.
High Pressure Systems
In a high pressure system, the air is dry and is moving downwards. As this system moves over the land it draws in moisture from the land surface. Consequently the moisture does not fall as rain and so the desert remains dry.
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Are you interested in discussing current issues? Join our school debating team.
- Excellent in English.
- Fond of reading
- Holding TOEFL score: at least 500.
- Having self confidence
Registration: Monday, January 6, 2009 at. 3.00 PM.
Venue: AV Room.
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Enjoy the Beauty of North Sumatra
Along the length of North Sumatra province crosses Bukit Barisan Mountains with peaks of numerous volcanoes. The land has thick virgin forests, lush vegetation, rice fields, mountain streams, rivers, waterfalls and sandy beaches. It has a rich flora and fauna. An abundance of birds, butterflies, buffaloes, deer, mouse deer, orangutans and many other export commodities make North Sumatra one of the richest provinces in Indonesia, as it produces more than 30 % of Indonesia's exports. The province offers the visitors, especially nature lovers, beautiful tropical panoramas, terraced rice fields, blue mountains, jungle covered hills, white sandy beaches, music, dance and folk arts.
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To improve comfort and cleanliness at our school, a number of dust bins should be increased.
When we look at classroom, school corridor and school yard, there papers, mineral water cups, straws, and napkins here and there. The condition of uncleanliness and discomfort really hinders learning and teaching environment. Litters thrown carelessly cause disease, especially empty plastic cups or glasses. They can be filled out with water coming from the rain. This can be placed for dangue mosquitoes to spread out. Besides, these rubbish can deteriorate the scene. Well painted wall and green school yard do not mean anything if litters and scattered everywhere.
Anyway I notice that most of the students in our school have responsibilities for their school environment. They put their litters on the proper places. But some are not diligent enough to find the dust bins. The numbers of dusts bins in our schols are not enough. More dust bins should be put beside each of steps, outside of the classrooms, and some more along the corridors. Probably one dust bin should be in every ten meters. So when students want to throw away their litters, they can find the dust bins easily. When school is equipped with sufficient dust bins, we do not have problems of filth and discomfort any more. Our school will be very clean and become a nice place to study.