Components of the environment
The
surface of the earth is a complex zone in which three main components of the
environment meet, overlap and interact.
Lithosphere
The
solid portion of the earth on which we live is called the Lithosphere. It
comprises the rocks of the earth’s crust and the thin layers of soil that
contain nutrient elements which sustain organisms. There are two main divisions
of the earth’s surface. The large landmasses are known as the continents and
the huge water bodies are called the ocean basins.
Hydrosphere
Water covers a very big area of the
earth’s surface and this area is called the Hydrosphere. The earth is called
the blue planet. More than 71 % of the earth is covered with water and
29 % is with land. Hydrosphere consists of water in all its forms. As running
water in oceans and rivers and in lakes, ice in glaciers, underground water and
the water vapor in atmosphere, all comprises the hydrosphere. More than 97 % of
the earth’s water is found in the oceans and is too salty for human use. A
large proportion of the rest of the water is in the form of ice sheets and
glaciers or under the ground and a very small percentage is available as fresh
water for human use.
Atmosphere
The
gaseous layer that surrounds the earth is called the Atmosphere. It provides us
with the air e breath and protects us from the harmful effects of sun’s rays.
The atmosphere extends up to a height of about 1,600 kilometers. The atmosphere
is divided into five layers based on composition, temperature and other
properties. These layers starting from earth’s surface are called the troposphere,
stratosphere, mesosphere, thermosphere and exosphere.
The atmosphere is composed mainly of
nitrogen and oxygen, which make up about 99% of clean, dry air. Nitrogen 78% ,
oxygen 21% and other gases like carbon dioxide, argon and others comprise
1% by volume. Oxygen is the breath of
life while nitrogen helps in the growth of living organisms. Carbon dioxide,
through present in minute amount is important as it absorbs heat radiated by
the earth, thereby keeping the planet warm. It is also essential for the growth
of plants.
