Transcript Chapter 22 The Atmosphere

Chapter 22
The Atmosphere
Composition of the Atmosphere
• Permanent:
• Nitrogen-78%
• Oxygen-21%,
• Others - 1%
• Variable:
• Water vapor (H2O)
• Carbon dioxide (CO2)
• Ozone (O3)
• Particulates
Composition of the Atmosphere
• 99% permanent gases and 1% variable
(trace) gases.
– Permanent gases - constant concentration with
time & space.
– Variable gases - varying concentration
depending upon where/when you are.
• All weather and climate are associated
the 1% variable gases.
Parts of Atmosphere important to
weather
1. Water Vapor
- more in warmer locations
- forms clouds and drives weather
- absorbs heat to keep earth warm
Water Vapor Imagery
2. Carbon Dioxide
• Absorbs energy
from the earth
3. Ozone
– Ozone high in the atmosphere is good
– Absorbs harmful UV rays
– Ozone here is formed naturally
- Ozone low in the atmosphere is bad
- creates smog
- made by humans
4. Particulates
- Volcanic dust, ash from fires, pollen
- Absorb water and helps to form clouds
- Absorbs/reflects sunlight
Atmospheric Pressure
• The weight of the air
above a point
• Decreases with altitude
• Also changes with
temperature and amount
of water vapor in the air
• Measured with a
barometer
• Standard Atmospheric
Pressure = 1 atm or 760
mm of mercury or
1000mb
Atmospheric
pressure
variation
with altitude
Measuring Pressure
Mercurial Barometer
-Tube filled with mercury
-air pressure pushes on
mercury from bottom
-causes mercury to rise
and fall
Aneroid Barometer
- Metal expands and
contracts with changes
in pressure
- Causes pointer to move
so pressure can be read
Barograph
- Recording aneroid
barometer
- Keeps track of pressure
over several days
Layers of the Atmosphere
Troposphere
•
•
•
•
•
•
Weather Sphere
Bottom Layer
Temperature decreases with height
Most clouds
Most water vapor
Most airplanes fly here
Stratosphere
• Ozone Layer
• Increase Temp with height because ozone absorbs
UV
Mesosphere
• Temperature decreases to coldest point at the
mesopause (-90⁰C)
• Many meteors burn up in this layer.
Thermosphere
• Air is very thin.
• Temperature increases due to absorption of solar
energy by nitrogen and oxygen
• Satellites orbit here
Ionosphere – part of the thermosphere
• Electrically charged layer
• AM radio waves reflect off of here
• Causes auroras
Create your OWN mnemonic phrase
to memorize the order of the five
layers. For example:
T = Troposphere = Terribly
S = Strostosphere = Scary
M = Mesosphere = Monsters
T = Thermosphere = Terrorize
E = Exosphere = Earth