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Monday, October 11, 2010

Dimensions of environment: the physical dimensions

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Environment and Environmental Science II
Before 1960s, the term environment was used merely for the surrounding of an organism which comprised physical factors only (temperature, light etc.). After 1960s rapid industrialisation and industrial developments gave birth to enormous problems at local, regional, national and international levels that forced people to rethink about environment and to develop a new approach towards it. This new approach included all the life forms in interactive relations to all the physical forms, forces and factors surrounding them. Thus, the dimensions of environment were expanded to include living organisms of all types together with all the non-living components of the nature. The dimensions of environment in modern times can be viewed in three forms – the Physical Form, the Biological Form and the Social Form.

Physical Dimensions of Environment
The word physical relates to natural forces and things that are not alive. The physical dimensions of the environment cover physical environmental conditions including temperature, sunlight, pressure, wind and air mass, geomagnetism, humidity, precipitation, topography(including water systems- rivers, lakes, ponds, ditches, seas and oceans except living organisms found in these systems and others.
The physical dimensions of environment cover a number of spheres like Atmosphere, Hydrosphere and Lithosphere.
The Envelop of air held around the earth by its magnetic force called gravity or the geomagnetism, is called as atmosphere.

 What is air?
The air is a mechanical mixture of different gases surrounding the earth. The specific composition of air and the radiations from the sun makes the atmosphere peculiar for the earth and its inhabitants
Importance of the study of atmosphere
The importance of the study of atmosphere has increased since last few decades. It is due to following facts- 
1. Air of atmosphere helps in the operation of different natural phenomena like water cycle, origin of wind, formation of clouds, rain fall and snow fall etc.
 2. Oxygen of atmosphere helps in the respiration of all organisms and Carbon dioxide helps in the process of photosynthesis. Other gases of atmosphere like nitrogen, organ and helium are isolated for industrial purposes.
3. The ozone layer of atmosphere checks harmful ultraviolet radiations against reaching to the earth. The ultraviolet radiations are very harmful to life as they cause skin cancer, cataract in eyes, burning of leaves of plants and death of smaller organisms etc. if these radiations are allowed to reach to the earth.
4. Atmosphere helps in the flying of birds and in aviation. It also acts as a medium for the transmission of sound waves.
5. The study of atmosphere helps in the forecasting about future changes in the weather conditions that often cause extreme events like natural disasters.
6. The advanced knowledge gained through the study of atmosphere helps in the advanced management and preparedness against natural disasters. 
II. Hydrosphere
Streams, rivers, seas, oceans, lakes, ponds and ditches and other water bodies are collectively called as Hydrosphere. In fact, it is the total water surface found on this planet. Water also occurs as invisible vapours in the air as mist, rain, ice, frost and snow.
Just as the differential heating of land surface causes circulation of air in the atmosphere, the differential heating of water surface causes circulation of water in the environment. The circulation of water through different spheres of the natural environment is called as Hydrological Cycle or the Water cycle.

Importance of Water
1. Water is a unique and universal solvent. It can dissolve most of the substances that come into its contact. This happens due to the ionic nature of water and its hydrogen bonding.
2. The Heat Capacity of water is very high. This is why water favours the life inhabiting it.
3. Water acts as a medium in nutrition and excretion processes of animals and plants. It is essential for the process of food production by plants through the process of photosynthesis. Due to these merits, water is called as the ‘matrix’ of life.
4. It helps in the regulation of temperature in the atmosphere. Seasonal changes and weather conditions depend on water.
5. Water forms major part of blood plasma and remains present in greater quantity in plant cells and tissues.
6. Water forms an important and convenient medium for transport or shipment.
7. The ultimate source of water on the earth is the rain water. If retained by soil, this water is used up by plants over long periods.

III. Lithosphere
The total of rock materials present on the crust of the earth and floors of oceans is called as lithosphere.
It consists of all those elements that have been provided by nature. It is approximately 80 kms thick on ocean floors and 100 to 50 kms thick beneath the continents. As a result of weathering of rocks, the weathered material gets mixed with decomposing organic materials to form soil which is the top layer of the earth. 

Thus, the mixture of weathered rock material, organic substances and humus is called as soil. Humus is a brown to black coloured organic material which is formed due to the biological decomposition of organic substances or wastes. It is very useful for plant nutrition. The process of soil formation is called as Paedogenesis

The soil has to face a number of climatic and biological forces that remove a big portion of the top soil. This is called as soil erosion. The soil erosion causes considerable damage to land and hampers agricultural production.  

Importance of Soil
Soil is an important physical system and an essential component of environment due to following fact-
1. It is the basis of life as it supports the growth and development of plants and plants are the sources of food and energy for living organisms.
2. It provides habitats to varieties of organisms including various decomposers who decompose dead organic materials and help in their recycling.
3. It provides nutrients to plants, oxygen to their roots and helps in the cycling of materials.
4. It breaks the dormancy of seeds and helps in their germination.
5. Soil is the store house of seeds of plants which acts as a reserve stock of food for numerous birds and other organisms.

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