Τετάρτη, 27 Ιανουαρίου 2010

Nature

Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general. It ranges in scale from the subatomic to the cosmic.
Earth (or, "the earth") is the only planet presently known to support life, and as such, its natural features are the subject of many fields of scientific research. Within the solar system, it is third nearest to the sun; it is the largest terrestrial planet and the fifth largest overall. Its most prominent climatic features are its two large polar regions, two relatively narrow temperate zones, and a wide equatorial tropical to subtropical region. Precipitation varies widely with location, from several metres of water per year to less than a millimetre. Seventy-one percent of the Earth's surface is covered by salt-water oceans. The remainder consists of continents and islands, with most of the inhabited land in the Northern Hemisphere.

The atmosphere of the Earth serves as a key factor in sustaining the planetary ecosystem. The thin layer of gases that envelops the Earth is held in place by the planet's gravity. Dry air consists of 78% nitrogen, 21% oxygen, 1% argon and other inert gases, carbon dioxide, etc.; but air also contains a variable amount of water vapour. The atmospheric pressure declines steadily with altitude, and has a scale height of about 8 kilometres at the Earth's surface: the height at which the atmospheric pressure has declined. The ozone layer of the Earth's atmosphere plays an important role in depleting the amount of ultraviolet (UV) radiation that reaches the surface. As DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.

Oceans, rivers, lakes are included in this planet, too. Ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas. More than half of this area is over 3,000 meters (9,800 ft) deep. A lake is a terrain feature a body of liquid on the surface of a world that is localized to the bottom of basin and moves slowly if it moves at all. On Earth, a body of water is considered a lake when it is inland, not part of the ocean, is larger and deeper than a pond, and is fed by a river. A river is a natural watercourse, usually freshwater, flowing toward an ocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including stream, creek, brook, rivulet, and rill; there is no general rule that defines what can be called a river.

Animals are a major group of this beautiful planet. There are a lot of animals on Earth distinguished into categories like mammals, fish, amphibians etc. All these animals need food, water, fresh air (oxygen) and their own space to live. The biggest numbers of wild animals live in Africa and around the Amazon.

In this planet we live, as well. Humans are the smartest bodies which have ever lived on this planet. We started our life here many years ago and we still exist. However, humans do not always care for the environment as they should. People tend to prefer their own convenience and luxury over a healthy natural environment. People want more cars, bigger houses, the latest computer technology, and packaged foods, etc. to make their life more comfortable.

The most serious ecologic
al problems of today are the pollution of air, water and soil, the destruction of the global ecosystem, the extinction of many species of animals and plants, the weather changes, acid rain, global warming of the Earth’s surface, the destruction of tropical rain forests and the hole in the ozone layer. These damages are caused by us, people, and our technical progress. Factories, power stations and motor vehicles pump large quantities of carbon dioxide and other waste gases into the air. Some poisonous gases dissolve in the water and in the atmosphere and then fall to the earth in the form of acid rain. Acid rain damages trees, buildings and kills fish. Rivers can also be polluted by industrial waste from factories and chemical fertilizers and pesticides used by farmers. Global warming is caused by the greenhouse effect. Normally, heat from the sun warms the earth and escapes back into space. But carbon dioxide and other gases in the atmosphere trap the sun’s heat, and this is slowly making the earth warmer.

The ozone layer is a layer of gas high above the surface of the earth that helps to protect it from the sun ultraviolet radiation. Scientists have recently discovered holes in the ozone layer, caused by substances called CFCs. CFCs are used in refrigerators, aerosol cans and in the manufacture of some pla
stic products. Now, don’t use these any such products, unless they are marked as “ozone-friendly”.

Rainforests help to control global warming because they absorb carbon dioxide. In recent years, large areas have been destroyed for wood or for farming. Many rainforests grow on poor soils, and when they are cut down or burned, the area may turn to desert. Many plant and animal species t
hat live there could become extinct.

People should use alternative fo
rms of energy. Electricity produced by solar, wind or water power doesn’t damage environment like the electricity made of coal, gas or oil. But solar, wind or water power is still too expensive. People should recycle and reuse, when used objects and materials can be used again.

Listen to: Amelie by Yann Tiersen

Created by:
Konstantinos Gavriilidis (GR), Nicola Leoce (IT), Elena Majtánová (SK)

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