Structure Of The Atmosphere Video Lecture | Social Studies (SST) Class 7

composition of the atmosphere the air we
breathe in is a mixture of many gases
nitrogen and oxygen gas make up the bulk
of the atmosphere carbon dioxide helium
ozone water vapor argon hydrogen and
dust are found in lesser quantities
78% of air is nitrogen along with air we
inhale nitrogen into our lungs and
exhale it
plants need nitrogen in large amounts
but they cannot take nitrogen directly
from the air
nitrogen-fixing bacteria that live in
the soil and roots of some plants
convert atmospheric nitrogen into form
usable by plants
21% of air is oxygen humans and animals
take oxygen from the air as they breathe
green plants produce oxygen during
photosynthesis in this way oxygen
content in the air remains constant if
we cut trees then this balance gets
disturbed green plants use carbon
dioxide during photosynthesis and
release oxygen
you
carbon dioxide oxygen balance is
disturbed by burning of fossil fuels as
this adds billions of tons of carbon
dioxide into the atmosphere each year
the increased volume of carbon dioxide
affects the Earth's weather and climate
carbon dioxide released in the
atmosphere creates a greenhouse effect
by trapping the heat radiated from the
earth it is therefore called a
greenhouse gas and without it the earth
would have been too cold to live in
however when atmospheric carbon dioxide
level increases due to factory smoke or
car fumes the heat retained increases
the temperature of the earth this is
called global warming
rise in temperature due to global
warming causes the snow in coldest parts
of the world to melt
as a result the sea level rises flooding
the coastal areas drastic climate
changes may lead to extinction of some
plants and animals in the long run