5.Biosphere.

The biosphere is the layer of the earth in which all life exists. All living organisms together with their environments make up the biosphere. These environments include the air (atmosphere), land (geosphere), rocks (lithosphere) and water (hydrosphere).

The biosphere is important because it is all of life. Without the biosphere, earth would be a lifeless planet like all the others in our solar systems. Also, the biosphere could not exist without water. Water is essential for all living organisms on earth and has played a very important role in the evolution of life on our planet. Life on earth began approximately 3.5 billion years ago in the oceans. At the time, earth was very different from what it is today.

The earliest forms of life were very simple organisms similar to modern bacteria.Over millions of years,more complex organisms evolved and in time, many different forms of life began to inhabit the land, the sky and the oceans. They all depended on each other to survive. The biosphere is like aladder. This ladder is known as the food chain, and all life depends on the first step of the ladder which is made up of plants. Animals eat the plants, bigger animals eat the smaller animals, and so on. In this way, all organisms are closely connected to their environment.

The biosphere is what keeps us alive. It gives us our food, water and the air that we breathe. Everything we need in order to grow and survive comes directly from the biosphere, so it is important to protect it, however, humans have not always done that. Humans have had a huge impact on the biosphere. Sometimes this has been good, but at other times it has been very destructive. The growing human population on earth means there is less room for other species and by destroying their habitats we have made many types of plants and animals extinct.

6.The earth`s atmosphere.

Earth is unique among the planets in the solar system. One of the most unique features of Earth is the presence of a stable atmosphere. The various gases that surround a planet make up its atmosphere. Earth’s atmosphere shapes our weather, climate, and vegetation patterns and makes life as we know it possible. Without air there would be no day-to-day weather changes. It would be extremely hot during the day and very cold at night. And, there would be no oxygen and no carbon dioxide to support human and plant life.

Components of the atmosphere. A great “ocean” of gases surrounding the earth for thousands of miles forms the earth’s atmosphere, usually known simply as the air. More than 98 per cent of the gases that make up the atmosphere, however, are found within 26 km of the earth’s surface. Farther above the earth, the gases — and the air — gradually thin out. Air in its natural state is a colorless, odorless, tasteless mixture of gases. Nitrogen makes up 78 per cent of dry air, oxygen makes up 2l per cent, and other gases such as carbon dioxide, helium, and ozone make up the remaining l per cent.

Along with gases, air nearly always contains small amounts of water vapor, dust, soot, pollen, seeds, and other particles. Winds, forest fires, and volcanic eruptions sweep many of these particles into the air naturally. Other particles release from chimneys, smokestacks, automobiles, and other polluters. Together, these particles create polluted air, such as the haze and smog that hangs over many cities today.

Weather is the condition of the atmosphere for a short period of time at a specific location. The average of daily weather conditions over a long period of time is known as climate. Certain location and place factors influence the distribution of climates over the earth’s surface. These factors, known as climatic controls, are latitude, altitude, and proximity to land and water.