Download Layers of the Atmosphere

The
Atmosphere
Characteristics of the Atmosphere
Composition:
•  78% nitrogen gas.
•  21% Oxygen
•  1% “Other”
•  0.9% Argon (noble gas)
•  0.04% CO2
•  0.06% is trace elements (tiny bits):
• Water vapor
• Ozone (O3)
• Methane (CH4)
• Other noble gases (He, Ne, Kr)
Characteristics of the Atmosphere
Pressure and Temperature:
•  The atmosphere is held around the Earth by
gravity. Gravity pulls gas molecules in the
atmosphere toward the Earth s surface,
causing air pressure.
•  As altitude increases, air pressure decreases.
•  Air temperature decreases as altitude
increases. Lower parts of the atmosphere are
warmer because they contain a high
percentage of gases that absorb solar energy.
Air Pressure
•  Atmospheric Pressure – amount of force or pressure
exerted by atmosphere on objects within it
• Stronger push = high pressure
• Weaker push = low pressure
• Differences in pressure cause air to move to even
out pressures. This is wind!
• Pressure and Density:
• Low air density = low pressure
• High air density = high pressure
• Pressure and Temperature (of contained particles)
• Low temperature = slow particles = low pressure
• High temperature = fast particles = high pressure
What Makes Wind?
Movie
Measuring Pressure
•  Barometer: A tool that measures the pressure in the
atmosphere. It is used by meteorologists to predict
weather patterns.
• Types of Barometers:
•  Water – colored water in sealed bubble with tube
•  Water in tube above line: low pressure
•  Water in tube below line: high pressure
•  Mercury – liquid mercury (Hg) rises/falls in a tube
as pressure rises/falls (where we get the term
millimeters of mercury or mmHg)
•  Aneroid – metal cell changes shape due to
changes in air pressure, which translate to the dial
Layers of the Atmosphere
•  The Troposphere: The Layer in Which We Live
The lowest layer of the atmosphere, it extends 4-12
miles above Earth, depending on your location.
Temperature drops as you climb higher because the
gases decrease (“thinner air”). Almost all weather
happens here.
•  The Stratosphere: Home of the Ozone Layer
Above the troposphere, it extends about 31 miles
above Earth. It contains a lot of oxygen, which
absorbs radiation and forms the Ozone. This
results in increasing temperature as height
increases. (closer to more ultraviolet radiation from
the Sun)
Layers of the Atmosphere
• The Mesosphere: The Middle Layer The middle
layer of the atmosphere extends about 53 miles
above Earth. The gases become thinner and are
less effected by UV rays, so temperature
decreases with height. It is the coldest layer (5F -184F). The gases are thick enough to slow
meteorites, where they burn up leaving meteor
showers.
Layers of the Atmosphere
•  The Thermosphere: The Edge of the
Atmosphere The uppermost atmospheric layer
extends 430 miles above Earth. The gases are
increasingly thinner, and can only absorb higher
energy UV and X-rays from the sun. Temperature
increases with height (closer to the sun’s rays).
•  The Exosphere: The Outermost Layer: 6200
miles above Earth and composted mostly of
Hydrogen and Helium, these particles are so
spread out that they rarely interact. They eventually
leave by the solar wind. This is where satellites
orbit.
Layers of the Atmosphere
•  The Ionosphere: Home of the Auroras Part of
the layers of the upper atmosphere, nitrogen and
oxygen atoms become ionized (charged) from
solar energy. This can result in auroras
Layers of the Atmosphere
Draw me!
Energy In the Atmosphere
•  Radiation: The Earth receives energy from the sun
by radiation. Radiation is the transfer of energy as
electromagnetic waves.
•  Conduction: Thermal conduction is the transfer of
thermal energy through contact with a material.
•  Convection: Convection is the transfer of thermal
energy by the circulation or movement of a liquid or
gas.
Atmospheric Heating
The Greenhouse Effect
•  The Greenhouse Effect: The greenhouse effect is
the process by which gases in the atmosphere absorb
thermal energy and radiate it back to Earth.
Global Warming
•  Greenhouse Gases and Global Warming Some
scientists think that an increase of greenhouse gases
in the atmosphere may be the cause of global
warming.
Why Air Moves
•  Uneven Heating by the Sun: Air rises at the Equator and
sinks at the poles. As the cold air sinks, it creates areas of
high pressure around the poles. This cold polar air then flows
toward the equator.
Why Air Moves
•  Pressure Belts Are Found Every 30º Convection cells
are separated by pressure belts, bands of high and low
pressure.
The Coriolis Effect
•  The Coriolis Effect The apparent curving of the
path of currents due to the Earth s rotation.
1835 – Gaspard Gustave Coriolis
observed and calculated veering
effect mathematically
Global Winds
Types of Global Winds
•  Polar Easterlies are the wind belts
that extend from the poles to 60°
latitude in both hemispheres.
•  Westerlies are the wind belts
found between 30° and 60° latitude
in both hemispheres.
•  Trade Winds are the winds that
blow from 30° latitude almost to the
equator in both hemispheres.
Global Winds
•  The Doldrums The trade winds of the
Northern and Southern Hemispheres meet
in an area around the equator.
•  The Horse Latitudes At about 30° north
and 30° south latitude, sinking air creates
an area of high pressure.
•  Jet Streams are narrow belts of highspeed winds that blow in the upper
troposphere and lower stratosphere.
Global Winds – Draw Me!
Local Winds
•  Generally move short distances and can blow from
any direction.
•  Mountain and valley breezes are examples of local
winds caused by an area s geography.
•  Sea and land breezes are affected by temperature.
Sea Breeze & Land Breeze
Sea Breeze
Land Breeze