Transcript Layers of the Atmosphere

Chapter 12, Section 3
Ch12 S3: Essential Questions
1. What are the four main
layers of the atmosphere?
2. What are the characteristics
of each layer?
Earth’s atmosphere is divided
into four main layers based
upon changes in temperature.
Layers of the
atmosphere
Troposphere
 Lowest layer of the atmosphere (closest to Earth)
 You live here
 Tropo means turning or changing (there is more
change in this layer than any other)
 Weather occurs here
 Shallowest layer (thinnest)
 Contains almost all the mass of the atmosphere
 It is 16 km thick at equator and less than 9 km thick at
poles
 As altitude increases, temperature decreases
 At the top, temp is about -60 ̊C. Water here forms
clouds of ice
Stratosphere
 Second layer of the atmosphere
 Reaches from troposphere to about 50 km above
surface of Earth
 Strato means layer or spread out
 Ozone layer is here (remember it protects living things
from ultraviolet radiation from Sun)
 Jets often fly here because it is calm
 As altitude increases, temperature increases (because
ozone layer absorbs heat)
Mesosphere
 Third layer
 Meso means middle
 Reaches from 50 km to 80 km above Earth’s surface
 Protects Earth’s surface from being hit by meteoroids
(chunks of stone and metal from space – but some still
get through)
 A shooting star is a trail of hot, glowing gases a
meteoroid leaves behind in the mesosphere
 Coldest layer - Temperatures reach – 90 ̊C at the top of
the mesosphere
 As altitude increases, temperature decreases
Asteroid
grazing
Earth’s
atmosphere
Thermosphere
 Outermost layer of our atmosphere
 Reaches from 80 km above Earth’s surface into outer
space. There is no definite upper limit
 Thermo means heat
 Thickest layer
 Hottest layer, temperatures reach up to 1,800 ̊C, but
you would not feel warm here (Find out Why?)
 As altitude increases, temperature increases
 Has two other layers
Ionosphere
 Lower layer of the Thermosphere
 Reaches from about 80 km to 400 km above Earth’s
surface
 Energy from the sun causes gas molecules here to
become electrically charged particles
 Radio waves bounce off ions back to Earth (makes
signals travel much farther at night)
 Auroras happen near the poles because of the
ionosphere – these are brilliant streaks of light in night
skies
Exosphere
 Exo means outer
 Is the outer portion of the thermosphere
 Reaches from about 400 km outward for thousands of
kilometers
 Space shuttles and satellites orbit Earth here
Remember:
Earth’s atmosphere is
divided into four main
layers based upon changes
in temperature.
- Layers of the Atmosphere
Can you pick out what might be the layers?
Review Quiz
1.
List the four main layers of the atmosphere in order
from the surface of Earth.
2. What is the hottest layer of the atmosphere?
a. Troposphere
b. Stratosphere
c. Mesosphere
d. Thermosphere
Quiz (continued)
3. What layer do you live in?
a. Troposphere
b. Stratosphere
c. Mesosphere
d. Thermosphere
4. What layer contains the ozone layer?
a. Troposphere
b. Stratosphere
c. Mesosphere
d. Thermosphere
Ch12 S3: Essential Questions
Answered
1. What are the four main
layers of the atmosphere?
Troposphere, stratosphere,
mesosphere, thermosphere
2. What are the characteristics of
each layer?
Troposphere: weather happens here,
we live here, thinnest layer, lowest
layer.
Stratosphere: ozone layer and jet
stream are here.
Mesosphere: coldest layer, shooting
stars happen here.
Thermosphere: thickest, hottest layer.
Stop Here
Temperature
 The average amount of energy of motion of each
molecule of a substance
 In the thermosphere the molecules are spaced far
apart in the thin air, so there are not enough of them
to collide with a thermometer and warm it very much
 In the thermosphere, an ordinary thermometer would
show a temperature well below 0 ̊C
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