Module - III

The environment consists of various segments such as atmosphere, hydrosphere, lithosphere and biosphere
Vital role played by atmosphere in the survival of life in this planet:

• The atmosphere is the protective blanket of gases which is surrounding the earth. It protects the earth from the hostile environment of outer space.
• It absorbs IR radiations emitted by the sun and reemitted from the earth and thus controls the temperature of the earth.
• The optical window runs from around 300 nm (ultraviolet-C) up into the range humans can see, the visible spectrum (commonly called light), at roughly 400–700 nm and continues to the infrared to around 1100 nm.
 There are also infrared and radio windows that transmit some infrared and radio waves at longer wavelengths. For example, the radio window runs from about one centimeter to about eleven-meter waves.

• It acts as a source for CO2 for plant photosynthesis and O2 for respiration.
• It acts as a source for nitrogen for nitrogen fixing bacteria and ammonia producing plants.
• The atmosphere transports water from ocean to land.

Hydrosphere:
The hydrosphere is a collective term given to all different forms of water. It includes all types of water resources such as oceans, seas, rivers, lakes, streams, reservoirs, glaciers and ground waters.

Lithosphere:
• The lithosphere consists of upper mantle and the crust.
 The crust is the earth’s outer skin that is accessible to human.
 The crust consists of rocks and soil of which the latter is the important part of lithosphere. It supports different forms of Life through Biomes, Ecosystems.
 Supplies all types of elements essential for Life and Human Society.


Biosphere:
• The biosphere refers to the realm of living organisms and their interactions with the environment (VIZ: atmosphere, hydrosphere and lithosphere)
• The biosphere is very large and complex and is divided into smaller units called ecosystems.
• Plants, animals and microorganisms which live in a definite zone along with physical factors such as soil, water and air constitute an ecosystem.
• Within each ecosystems there are dynamic inter relationships between living forms and their physical environment