COMPOSITION AND
LAYERS OF THE
ATMOSPHERE
Composition of the Atmosphere
NITROGEN
 The most abundant gas in the
atmosphere.
 It is a stable gas , it doesn’t react into
the chemical combination easily.
 It enters the system of the living things
in the form of nitrate(NO3) and
ammonia(NH3).
 Nitrogen cycle.
Nitrogen Cycle
OXYGEN
 The second most abundant gas in the
atmosphere.
 Living things take in oxygen during
respiration.
 Photosynthesis contributes to the oxygen
content of the atmosphere by releasing it
as a by product of the process.
PHOTOSYNTHESIS
CARBON DIOXIDE
 It comprises a tiny fraction of the
atmospheric gases.
 Living things release carbon dioxide
during respiration.
 It is important for plants because it is a
raw material for photosynthesis.
 Deforestation and fossil fuel
combustion.
Carbon dioxide-Oxygen Cycle
DIFFERENT
ATMOSPHERIC
LAYERS
LAYERS OF THE ATMOSPHERE
TROPOSPHERE
 The layer that is nearest to Earth’s surface.
 It is the densest layer since it contains about
75% of the atmospheric gases enumerated
from above.
 Clouds of all types, storms, and all types of
weather phenomena characterized this
layer.
 Tropopause the upper boundary of the
troposphere.
STRATOSPHERE
 The layer immediately above the
troposphere.
 Less dense and relatively dry.
 The ozone layer is found in this layer,
which absorbs the ultraviolet radiation
and transform it to heat.
 The upper boundary of the
stratosphere is called stratopause.
MESOSPHERE
 This layer start just above the
stratosphere.
 The temperature drops significantly in
this layer to as low as -93 degrees
Celsius( because the altitude increases).
 The mesopause separates the
mesosphere from the next layer of the
atmosphere.
THERMOSPHERE
 The thermosphere start just above the mesosphere.
 This layer contains a tiny fraction of the atmospheric
gases.
 Chemical reactions occur much faster in this layer
due to the increasing heat from the sun.
 The thermopause separates the thermosphere from
the exosphere.
 Exosphere is a thin transition layer into the outer
space, here hydrogen atoms in the atmosphere flee
off the outer space.
 At the lower region of the thermosphere,
blending with the upper region of the
mesosphere is a layer called ionosphere, which
is thick and rich in ions.
 The ionosphere plays important role in radio
and telecommunications operation on earth.