NC Essential Standard: Compare the
composition, properties, and structure of
Earth’s atmosphere to include: mixtures of
gases and differences in temperatures and
pressure within layers.
 All weather and the air you breathe!
 The lowest and most important layer.
 Contains 90%
of all the gas
molecules in
the
atmosphere!
 Why?
Temperature is highest at the surface of the
earth and decreases with altitude.
High altitude, colder
temperatures
Low altitude, warmer
temperatures
 The Sun sends solar radiation through the atmosphere
in the form of electromagnetic waves.
 Rock, soil, and water absorbs the Sun’s light and
radiates it back as heat.
 As you move further from the ground, you are moving
further from the source of this reflective heat.
 Also, there are less
molecules in the air as
you increase in altitude.
Less molecules
= less collisions
= less heat
 Second layer of the atmosphere
 Contains the ozone layer that helps to trap heat
in the atmosphere.
 As you increase in altitude,
temperature increases.
 Warm air sits above cool air = stable
= no weather.
 How is this different than the troposphere?
The pilot says, “We are no at our cruising altitude of
30,000 feet.” Why do planes fly so high in the air?
Out of the troposphere and into the stratosphere.
Fuel costs are lower because there is less friction due to
the lower air density…there’s also less turbulence.
 Middle layer
 Temperature decreases with altitude
(heat is from the stratosphere)
 Extremely low density of molecules
 Meteor showers
occur here
 The pressure is so low that liquids would
boil at normal body temperature.
 Your blood would boil without a space suit!
 Thinking Question!
If pressure decreases with altitude…and your
blood would boil in the mesosphere….
Does water boil faster in
the mountains or at sea level?
Answer: The Mountains
 Fourth layer of atmosphere from the
surface of the earth.
 Very low density of molecules
The gases of the thermosphere are increasingly thinner than in the
mesosphere. As such, only the higher energy ultraviolet and x-ray
radiation from the sun is absorbed. But because of this absorption, the
temperature increases with height and can reach as high as 3,600°F
(2,000°C) near the top of this layer.
However, despite the high temperature, this layer of the atmosphere
would still feel very cold to our skin because of the extremely thin air. The
total amount of energy from the very few molecules in this layer is not
sufficient enough to heat our skin
 (430 miles to outerspace)
 Outermost layer of the atmosphere.
* Source of all of the energy on Earth.
* Energy from the sun must pass through
the different layers of the atmosphere
before it hits the surface.
• The atmosphere is
divided into
different layers
based on the shifts
in the temperature
increasing or
decreasing with
altitude. It is a
pattern!!
Air pressure and density DECREASE as you
increase in altitude (less air the further up you
go!).
Density: the amount of molecules (mass) in a
given volume of substance.
Gravity pulls molecules down to Earth!
= The force of the
air weighing down
over a unit of area.
-
-
Air molecules constantly bounce off
each other and push on all the surfaces
they touch.
The amount of pressure exerted by our
atmosphere is about 14.7 pounds per
square inch.
Why don’t you feel it?
All the air and liquids in your body push outward
with the same pressure!
= any instrument that measures air pressure.
“bar” refers to “air pressure”
The flexible chamber on the barometer contracts when the air pressure
increases and expands when air pressure decreases.
= a line on a map connecting points having the
same atmospheric pressure.