Composition of the Atmosphere

The atmosphere is a mixture of
gases surrounding Earth.
 Nitrogen (78%), the most common
atmospheric gas, is released when dead
plants and dead animals break down and
also when volcanoes erupt.
 Oxygen (21%), the second most common
atmospheric gas, is made by
phytoplankton and plants.
 The remaining 1% of the atmosphere is
made up of argon, carbon dioxide, water
vapor and other gases.
Air Pressure (Atmospheric Pressure)

Gravity pulls gas
molecules toward
Earth, causing Air
Pressure, which is the
force with which air
molecules push on a
surface.
 Strongest at Earth’s
surface
 Air Pressure decreases
as altitude increseses
Temperature
Also changes as altitude increases
 The composition of atmospheric layers affect their
temperature.
 The temperature differences result from the
amount of gases present in each layer that absorb
solar energy
 As the amount of gases that absorb solar energy
increases, the temperature increases

Layers of the Atmosphere

The Earth’s atmosphere is divided into five layers based
on their composition.
The Silly Mouse Took Ex-lax
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Troposphere

Lowest layer of the atmosphere, lying next to Earth’s
surface. Temperature decreases with altitude.

Contains almost 90% of the atmosphere’s mass.

Nearly all weather occurs in this layer.

Water vapor, clouds, air pollution, and organisms are also
found here.
Stratosphere

The atmospheric layer
above the troposphere.

Contains little moisture

Lower stratosphere is
extremely cold, but
temperature increases as
altitude increases in the
stratosphere.
 The Ozone Layer- The
upper layer of the
Stratosphere.
 it absorbs UV radiation
from the sun, warming the
air  protects life on
Earth.
Mesosphere

The middle layer of the
atmosphere.

Coldest layer

Temperature decreases as
altitude increases, just like
the troposphere.

The upper layer of the
Mesosphere (lower portion
of the Thermosohere) is
called the Ionosphere
Ionosphere

The lower part of the
thermosphere is considered
the Ionosphere.

As a result of N2 atoms and O2
atoms absorbing the radiation,
temperature in the
thermosphere rises, and gas
particles become electrically
charged  ions.

Ions within the ionosphere
can radiate energy as
shimmering lights called
auroras, a.k.a. the Northern
and Southern Lights.
Thermosphere

Uppermost atmospheric layer.

Temperature again increases steadily with altitude because
nitrogen and oxygen atoms absorb solar radiation.
 This releases thermal energy.

No data to determine its upper boundary.
 Blends with the vacuum of space (exosphere).
Exosphere

The last layer of the
atmosphere. Very difficult to
determine where it stops
and space begins

Very few atoms in this layer
of the atmosphere
Videos

Antarctica Auroras

Aurora Northern Lights as seen from
Space