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Atmosphere in Motion
Chapter 16
Atmosphere
• What is the atmosphere?
– A layer of gases surrounding Earth
– Composed of matter and has mass
– Subject to the pull of gravity
Atmosphere
• Earth's Atmosphere is:
A mixture of gases with some suspended
solids and liquids.
• Three common solids (aerosols)in
atmosphere:
• Ice
• Dust
• Salt - from ocean spray
Gas Composition of Earth's
Atmosphere
• Nitrogen - 78% of
atmosphere
• Oxygen - 21% of
atmosphere
• Trace gases - 1% - Neon,
Helium, Hydrogen,
Methane,
Carbon Dioxide Formation of the
Atmosphere:
• The Earth's atmosphere was formed by a
process in which gases like carbon dioxide,
water vapor, sulphur dioxide and nitrogen
were released from the interior of the Earth
from volcanoes and other processes.
Atmosphere
• Levels
–Troposphere–Stratosphere
–Mesosphere
–Thermosphere
–Exosphere
Levels of Atmosphere
• Troposphere- approx. ground to 10 kilometers
( approx 7 miles up)
– The closest layer to the Earth.
– Contains 75% of our atmospheres gases
– Weather clouds and smog occur in the
troposphere
• The troposphere is the layer where most of the
world's weather takes place.
• Since temperature decreases with altitude in the
troposphere, warm air near the surface of the
Earth can readily rise, being less dense than the
colder air above it.
• air molecules can travel to the top of the
troposphere and back down again in a just a few
days.
• vertical movement or convection of air generates
clouds and ultimately rain from the moisture
within the air, and gives rise to much of the
weather which we experience.
Stratosphere
• approximately 10 km - 45 km up (approx
7miles-30miles)
• The ozone layer is located here
• the jet stream is located here
• Little or no water vapor here
• a layer in which temperatures rises with increasing
altitude.
• At the top of the stratosphere the thin air may
attain temperatures close to 0°C. This rise in
temperature is caused by the absorption of
ultraviolet (UV) radiation from the Sun by the
ozone layer.
• Such a temperature profile creates very stable
atmospheric conditions, and the stratosphere lacks
the air turbulence that is so prevalent in the
troposphere.
• almost completely free of clouds or other forms of
weather.
• Mesosphere - approximately 45 km -95 km up
(30 - 50 miles up)
– the coldest part of the atmosphere
Thermosphere • approximately 95 km -to 500 km (50 miles and
up)
– Warmest layer of the atmosphere.
• lower layer of thermosphere is called the
ionosphere
IONOSPHERE
• made of electronically charged particles.
• reflects radio waves
• In the daytime this layer interferes with radio
waves since suns energy charges the particles to
much and causes problems a lot of static.
• At night it is less charged. This is why it is easier
to hear AM radio late at night
Exosphere
• approximately 500 kilometers and beyond
– Outer most layer of our atmosphere
– Very few air molecules in this layer
– No clear boundary between this layer and space