Our atmosphere serves two
1. Protects life on Earth from the Sun’s
Atmosphere harmful rays.
2. Maintains a balance between amounts of
heat absorbed from the sun and the
amount of heat that escapes back into
A layer of air that forms a
protective covering around the
Composition of the atmosphere: The atmosphere is composed of:
• Solids- dust, pollen, salt
• Liquids- water etc.
• Nitrogen (78%) produced from
– volcanic eruptions,
– dead and decaying plants.
• Oxygen (21%)
– produced by plants (photosynthesis)
Atmosphere is composed of 5 layers.
These layers are based on pressure and temperature,
which are affected by altitude.
Air Pressure Temperature
-as altitude increases, - as altitude increases
air pressure decreases temperature changes
Which are effected by
As altitude increases, As altitude changes, so does the
air pressure decreases. temperature.
Both air pressure and temperature • Troposphere: 0 – 16
are affected by the altitude • Tropo=turning or
• As altitude increases, pressure decreases.
The molecules at the bottom layer • Weather takes place
(Troposphere) have more pressure on
them to force them together than those at • 90% of the
the top layer (Thermosphere). mass
• Temperature differences result from the 0°c
• - 6 at the top of the
way solar energy is absorbed as it moves troposphere
down through the layers of the • As altitude increases,
• Mesosphere: 50 – 80 km
• Stratosphere: 16 – 50 km
• Meso = middle
• Strato= layer or spreading out • Temperature decreases
• Jet stream = contains broad,
as altitude increases.
fast flowing “rivers of air” called • Outer mesosphere is the
jet streams. These jet streams coldest part of the
can change weather patterns atmosphere. -93°c at the
in the troposphere. top.
• Upper layer is warmer than • Protects Earth’s surface.
lower due to ozone layer. This is where meteoroids
• Ozone layer= O3 (Ozone) burn up upon entry into
absorbs sun’s ultraviolet rays, the atmosphere:
so temperature increases. IT “shooting stars”.
is very thin, only 2.5-3.5 mm • Scientists have recently
thick. O2 (Oxygen) vs O3
windstorms with winds
• -60°c to 0°c speeds up to 320 km/h in
• Thermosphere: 80 – 550 • Lower layer of the
km thermosphere composed
primarily of oxygen.
• Thermo = heat
• Absorbs x-rays and gamma
• Largest layer, .001 rays, which contribute to the
percent as dense as the high temperature and cause
the gas molecules to become
air at sea level. electronically charged (ions).
• Temperature increases • Aurora Borealis/Australis: The
as altitude increases. northern and southern lights.
Particles from the sun enter
Temperatures reach and strike oxygen and nitrogen
1700°c. particles, causing them to
• Very hot because energy
• The ionosphere can reflect
coming from the sun many types of radio waves,
strikes this layer first. allowing them to bounce
around the world.
• Energy = heat
• Exosphere: Above 550
km 5 Layers Revisited
• No true end of
molecules simply break
free of Earth’s gravity and
• Space shuttles, ISS
Station) and satellites
orbit the earth in this
layer. This is how long
distance calls, satellite
TV, internet, cell phones,
etc., reach you.