Tuesday, December 26, 2006

History of India

Stone Age rock shelters with paintings at Bhimbetka in the state of Madhya Pradesh are the earliest known traces of human life in India. The first known permanent settlements appeared over 9,000 years ago and gradually developed into the Indus Valley Civilization, dating back to 3300 BCE in western India. It was followed by the Vedic Civilization which laid the foundations of Hinduism and other cultural aspects of early Indian society. From around 550 BCE, many independent kingdoms and republics known as the Mahajanapadas were established across the country laying the foundations of ancient India.

The empire built by the Maurya dynasty under Emperor Ashoka the Great united most of modern Southern Asia except the Dravidian kingdoms in the south. From 180 BCE, a series of invasions from Central Asia followed including the Indo-Greeks, Indo-Scythians, Indo-Parthians and Kushans in the north-western Indian Subcontinent. From the third century CE, the Gupta dynasty oversaw the period referred to as ancient India's "Golden Age." While the north had larger, fewer kingdoms, in the south there were several dynasties such as the Chalukyas, Rashtrakutas, Hoysalas, Cheras, Cholas, Pallavas and Pandyas in different times and regions.

Monday, December 18, 2006

Hail formation

Hail forms on condensation nuclei such as dust, bugs, or ice crystals, when super cooled water freezes on make contact with. In clouds contains large numbers of super cooled water droplets, these ice nuclei grow quickly at the expense of the liquid droplets because the saturation vapor pressure over ice is slightly less than the saturation vapor pressure over water. If the hail stones grow large enough, latent heat released by further freezing may melt the external shell of the hail stone. The development that follows, usually called wet growth, is more efficient because the liquid outer shell allows the stone to accrete other smaller hail stones in addition to super cooled droplets.

Once a hailstone become too heavy to be supported by the storm's updraft it falls out of the cloud. The reason rain can't fall, is typically because of the tough winds inside a thunderstorm cloud. These winds hold the rain and freeze it. As the process repeats, the hail grows gradually larger. When a hail stone is cut in half, a series of concentric rings, like that of an onion, are revealed. From these rings we can determine the total number of times the hail stone had traveled to the top of the storm before falling to the ground.

Tuesday, December 12, 2006

Mean sea level pressure

Mean sea level pressure is the pressure at sea level or the station pressure condensed to sea level assuming an isothermal layer at the station temperature. This is the pressure usually given in weather reports on radio, television, and newspapers. When barometers in the home are set to match the local weather reports, they measure pressure condensed to sea level, not the actual local atmospheric pressure. The reduction to sea level means that the usual range of fluctuations in pressure is the same for everyone. The pressures which are measured high pressure or low pressure do not depend on geographical location. This makes isobars on a weather map meaningful and useful tool. The altimeter setting in aviation, set either QNH or QFE, is another atmospheric pressure reduced to sea level, but the method of making this reduction differs slightly.

QNH barometric altimeter setting which will cause the altimeter to read airfield elevation when on the airfield. In ISA temperature conditions the altimeter will read altitude above mean sea level in the vicinity of the airfield.

QFE barometric altimeter setting which will cause an altimeter to read zero when at the reference datum of a particular airfield. In ISA temperature conditions the altimeter will read height above the datum in the vicinity of the airfield.

Monday, December 04, 2006

Immigration and multiculturalism

Since the time of olden Rome, the city has always been a site for colonization. This once extensive to all reaches of the Roman Empire, but was more cramped to the rest of Italy in later centuries, as Rome's political power waned. Still, many of its citizens' families invent from outside the city, and the Romanesco phrase Romano de Roma has been coined to indicate someone who descends from a family that has lived in Rome for at least seven generations, the mark of a "true" Roman.

Over the next half of 20th century, Rome has seen rising immigration from other countries. There currently is an important immigrant population, including a great number of clandestine. The 2005 ISTAT estimations state that 145,000 immigrants live in the comune, or 5.69% of the total comune inhabitants. The foreign population in the metropolitan area of Rome consists in 206,000 persons, or 5.37% of the total urban area population. The foreign population in the metropolitan area of Rome is about 248,000 persons or 4.67% of the whole metropolitan area population. By far the largest number of immigrants is Eastern European, with the largest figures of foreigners coming from Romania, The Philippines, Poland, Albania, Peru, Bangladesh, and Ukraine.

Probably as a result of its multiethnic past, the city has reacted with less complexity to the current waves of immigration into Italy. In meticulous, Mayor Walter Veltroni has made multiculturalism one of the key points of supporting program; inhabitants of Rome who are not citizens of an EU country are now permitted to elect their own legislature in the city council, even if they do not embrace formal legal residence in Rome.