The Atmosphere
What is the atmosphere?
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The thin layer of gases that
surrounds our planet.
Weather is the condition of
th...
 Weather :

state of
atmosphere at any given
time and place
– temperature
– precipitation
– air pressure
– wind
– humidit...
Climate
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Aggregate (average) of weather
conditions over a long period of time.
– Example: A place that doesn't get much
...
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The Composition of the
Atmosphere

Nitrogen makes up 78% of our atmosphere
Oxygen makes up 21%
Argon makes up alm...
Trace elements/compounds
Carbon dioxide: plants use to produce
food. Plants take in CO2 and give off
oxygen as a waste pro...
Ozone
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Ozone is a molecule of
oxygen with 3 oxygen atoms
instead of 2.
Often formed when
lightning interacts with
...
Earth’s Early Atmosphere
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The Precambrian atmosphere was
composed mainly of nitrogen and carbon
dioxide, along wit...
Precambrian Life

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The first life on Earth was
cyanobacteria (like single
celled blue-green algae).
They used p...
Layers of the
Atmosphere
Pressure
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Pressure is a force that acts
over a certain area.
Liquids and gases are fluid. Fluid;
are any material ...
Air Pressure
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Air pressure is the
result of the column
of air that is above
you.
There is so much air
above you th...
Why are we not crushed
by air pressure?
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Air pressure is
equal in all
directions.
So air pushes
equally in all sides
...
Units of Air Pressure
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TV weather stations
and aviation use
inches of mercury.
Meteorologists (and
the NWS) use
milli...
Altitude and Density
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As the air pressure
decreases, the density of
the air decreases. The
air particles are not
squa...
Temperature and the
Troposphere
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Troposphere:
temperature at surface
is warmed by the earth
absorbing energy from
...
Temperature and the
Stratosphere
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Ozone absorbs
ultraviolet radiation
from the sun, causing
the temperature to
increase.
Temperature and the
Mesosphere
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This layer does not
absorb energy
from the sun, so it
starts to cool
again.
Without
g...
Temperature and the
Thermosphere
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Solar radiation first hits
this layer, so the few
particles that are here can
ga...
The Troposphere
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Lowest (inner) layer
weather occurs here
we live in it.
“tropo” means turning
or changing c...
The Stratosphere
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“strato ” means layer
or spreading out
Contains the ozone
layer which absorbs
energy and causes ...
The Mesosphere
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Drop in
temperature
marks beginning of
mesosphere
“Meso” means
middle
Most meteors
burn up here
The Thermosphere
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Very top layer
Air is very, very thin, about
1/1000th as dense as the air at
sea level
“...
The Ionosphere
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Energy from sun strips the
electrons from the gas
molecules creating charged
particles called ions...
The Exosphere
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“Exo” means outer
Extends for 1000’s
of miles
Satellites orbit
here
No definite edge
Molecules
...
Atmospheric Layers, Air Pressure, Weather Variables
Atmospheric Layers, Air Pressure, Weather Variables
Atmospheric Layers, Air Pressure, Weather Variables
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Atmospheric Layers, Air Pressure, Weather Variables

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Atmospheric Layers, Air Pressure, Weather Variables

  1. 1. The Atmosphere
  2. 2. What is the atmosphere?        The thin layer of gases that surrounds our planet. Weather is the condition of the atmosphere at a certain place and time. Our atmosphere makes life possible on our planet. Provides us with oxygen. Keeps surface warm so water can exist as a liquid. Protects the surface from dangerous radiation from the sun. Protects us from most meteoroids or rocks from space.
  3. 3.  Weather : state of atmosphere at any given time and place – temperature – precipitation – air pressure – wind – humidity
  4. 4. Climate  Aggregate (average) of weather conditions over a long period of time. – Example: A place that doesn't get much rain over many years would have a dry climate. A place where it stays cold for most of the year would have a cold climate.  Look out your window any day, any time and you see weather. Look out your window every day for a month or longer, observe the weather each day, and you can determine the climate.
  5. 5.     The Composition of the Atmosphere Nitrogen makes up 78% of our atmosphere Oxygen makes up 21% Argon makes up almost 1% All other gases have only trace amounts
  6. 6. Trace elements/compounds Carbon dioxide: plants use to produce food. Plants take in CO2 and give off oxygen as a waste product.  Animals take in oxygen to make energy and give off CO2 as a waste product.   Fossil fuels (coal, oil, natural gas) give off CO2 when they are burned. Rising CO2 levels may cause global warming.  The fizz in soda is really CO2 bubbles.  Dry ice is CO in the solid state.
  7. 7. Ozone    Ozone is a molecule of oxygen with 3 oxygen atoms instead of 2. Often formed when lightning interacts with oxygen in the air or by UV rays in the upper atmosphere. Forms a layer in the atmosphere that absorbs ultraviolet radiation from the sun. Without this layer life might not be possible on the surface of the planet.
  8. 8. Earth’s Early Atmosphere    The Precambrian atmosphere was composed mainly of nitrogen and carbon dioxide, along with some methane and ammonia. Volcanoes spewed water vapor, carbon monoxide, and even more nitrogen and carbon dioxide into the air. Comets also contributed water vapor, but no free oxygen. So where did the abundant oxygen that has made life as we know it come from?
  9. 9. Precambrian Life     The first life on Earth was cyanobacteria (like single celled blue-green algae). They used photosynthesis to turn CO2 into the food and energy they needed to survive. Photosynthesis gives off oxygen as a waste product. So over the millions of years, oxygen given off by algae built up in the atmosphere, while the amount of CO2 declined.
  10. 10. Layers of the Atmosphere
  11. 11. Pressure    Pressure is a force that acts over a certain area. Liquids and gases are fluid. Fluid; are any material that is able to flow. Fluids exert pressure because of the motion of their particles. Pressure will always move from a high pressure to a low pressure area. The pressure will always try to equalize. You see this when you get a hole in your bicycle tire.
  12. 12. Air Pressure    Air pressure is the result of the column of air that is above you. There is so much air above you that at sea level you have 14.7 lbs/in2 pushing on you. Gravity causes most of the air to be pulled down to the surface.
  13. 13. Why are we not crushed by air pressure?   Air pressure is equal in all directions. So air pushes equally in all sides of us. The forces are balanced!
  14. 14. Units of Air Pressure   TV weather stations and aviation use inches of mercury. Meteorologists (and the NWS) use millibars, an SI unit.
  15. 15. Altitude and Density   As the air pressure decreases, the density of the air decreases. The air particles are not squashed together as tightly the higher one goes. This is caused by gravity! The air at sea level and at 6km has the same 21% oxygen, but at 6km there are fewer molecules, so you take in less oxygen with each breath.
  16. 16. Temperature and the Troposphere    Troposphere: temperature at surface is warmed by the earth absorbing energy from the sun . Convection currents carry the heat upward, so the air cools as it rises. The air cools by about 6.5°C for every 1-km above the ground.
  17. 17. Temperature and the Stratosphere  Ozone absorbs ultraviolet radiation from the sun, causing the temperature to increase.
  18. 18. Temperature and the Mesosphere   This layer does not absorb energy from the sun, so it starts to cool again. Without greenhouse gases, energy pretty much passes straight through!
  19. 19. Temperature and the Thermosphere    Solar radiation first hits this layer, so the few particles that are here can gain lots of energy. They move rapidly, so they have a very high temperature. But the air is so thin here that it takes special instruments to measure the temperature accurately. So even though it is very hot (over 1000°C), it would feel cold because there are so few particles to transfer heat to you.
  20. 20. The Troposphere       Lowest (inner) layer weather occurs here we live in it. “tropo” means turning or changing conditions depth varies from 9km above the poles to 16km at the equator thinnest layer, but contains most of the mass (90%).
  21. 21. The Stratosphere    “strato ” means layer or spreading out Contains the ozone layer which absorbs energy and causes the temperature to rise The ozone layer protects the surface from dangerous UV rays
  22. 22. The Mesosphere    Drop in temperature marks beginning of mesosphere “Meso” means middle Most meteors burn up here
  23. 23. The Thermosphere        Very top layer Air is very, very thin, about 1/1000th as dense as the air at sea level “Thermo” means heat Extends from 80km to space No definite outer edge Very hot (over 1000°C), but since air is so thin it would not feel warm at all. Divided into two parts, the ionosphere and the exosphere
  24. 24. The Ionosphere    Energy from sun strips the electrons from the gas molecules creating charged particles called ions. Radio waves can bounce off of ions, allowing radio waves to travel great distances. The aurora borealis (Northern Lights) occur here
  25. 25. The Exosphere      “Exo” means outer Extends for 1000’s of miles Satellites orbit here No definite edge Molecules gradually escape out into space

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