17.1 Atmosphere Characteristics
Weather vs. Climate
 Weather is constantly changing, and it
refers to the state of the atmosphere at any
given time and place.
 Climate, however, is based on observations
of weather that have been collected over
many years. Climate helps describe a place
or region.
Volume of Clean, Dry Air
What is the most
abundant gas in
our atmosphere?
What is the
second most
common gas?
17.1 Atmosphere Characteristics
Composition of the Atmosphere
 Variable Components
Water vapor is the source of all clouds and
precipitation
carbon dioxide, water vapor absorbs heat given
off by Earth. It also absorbs some solar energy.
Ozone is a form of oxygen that combines three
oxygen atoms into each molecule (O3).
ozone filters UV radiation in the stratosphere
allowing life to exist as we know it,
In troposphere ozone causes smog
Primary Pollutants
What is a primary pollutant?
What is responsible for the majority of the
primary pollutants?
17.1 Atmosphere Characteristics
Height and Structure of the
Atmosphere
 Pressure Changes affect temprature
Atmospheric pressure is simply the weight of the
air above.
An increase in altitude = decrease in pressure
Decreases in pressure =decrease in temperature
Atmospheric Pressure vs. Altitude
Why does the
atmosphere
thin (become
less dense)
with altitude?
What affect
does this have
on temperature?
17.1 Atmosphere Characteristics
Height and Structure of the
Atmosphere
 Temperature Changes
Why is the • The atmosphere is divided vertically into four layers
Atmosphere based on temperature change.
Divided into • troposphere bottom layer of the atmosphere
Layers?
where temperature decreases with an increase in
altitude. Decreased pressure = decreased temp
• stratosphere layer on top of troposphere
temperature gradual increase because of O3
Snowy Mountaintops Contrast with
Warmer Snow-Free Lowlands
17.1 Atmosphere Characteristics
Height and Structure of the
Atmosphere
 Temperature Changes
• mesosphere the layer above the stratosphere
and is characterized by decreasing
temperatures with height, contains no O3
• thermosphere the layer above the mesosphere
and is characterized by increasing temperatures
due to the absorption of very short-wave solar
energy, atoms absorb max energy
Thermal Structure of the Atmosphere
17.1 Atmosphere Characteristics
Earth-Sun Relationships
 Earth’s Motions
• rotation = day and night; revolution = seasons
 Why do we have seasons?
• Seasonal changes occur because of earths
revolution around the sun and Earth’s axis is
tilted to 23.5O
Tilt of Earth’s Axis
17.1 Atmosphere Characteristics
Earth-Sun Relationships
 Solstices and Equinoxes
• summer solstice occurs on June 21 or 22 in the
Northern Hemisphere and is the “official” first day
of summer.
• winter solstice occurs on December 21 or 22 in
the Northern Hemisphere and is the “official” first
day of winter.
During our winter solstice what season is it in Australia?
17.1 Atmosphere Characteristics
Earth-Sun Relationships
 Solstices and Equinoxes
• autumnal equinox (Fall) occurs on September
22 or 23 in the Northern Hemisphere.
• spring equinox (vernal) occurs on March 21 or
22 in the Northern Hemisphere.
17.1 Atmosphere Characteristics
How is the length of daylight compared
to the length of darkness determined?
is determined by Earth’s position in orbit. Think
of the Arctic and Antarctic circle.
•
http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html
Solstices and Equinoxes
17.2 Heating the Atmosphere
Energy Transfer as Heat
 Heat energy transferred from one object to
another because of a difference in the
objects’ temperature.
 Temperature a measure of the average
kinetic energy a substance, hot more kinetic
energy, cold less kinetic energy
17.2 Heating the Atmosphere
What are the three mechanisms of energy
transfer as heat?
1. Conduction transfer of heat through solids
What are insulators? What are conductors?
2. Convection transfer of heat through fluids
17.2 Heating the Atmosphere
3. Radiation transfer of energy (heat) through
space by electromagnetic waves, can travel
through the vacuum of space others can not
How does wavelength
Relate to radiant
temperature?
6000Co=11000Fo
Energy Transfer as Heat
17.2 Heating the Atmosphere
Electromagnetic Waves everything that has heat
emits these waves. Energy emitted by the sun are
part of the electromagnetic spectrum
Are good absorbers also good emitters of radiant energy?
Visible Light Consists
of an Array of Colors
Why can you see the spectrum of electromagnetic waves?
Solar Radiation
What Happens to Solar Radiation?
17.2 Heating the Atmosphere
What Happens to Solar Radiation?
• Reflection when light bounces off an object, with
same intensity as incident radiation.
• Scattering when light bounces off an object
producing a larger number of weaker rays that
travel in different directions.
17.2 Heating the Atmosphere
 Absorption
• 50 percent of the solar energy that strikes the top
of the atmosphere reaches Earth’s surface and
is absorbed.
• greenhouse effect heating of Earth’s surface
and atmosphere from solar radiation being
absorbed and emitted by the atmosphere, two
main gasses involved water vapor and carbon
dioxide.
Global warming (climate change): the Green House
Effect sped up by human activity
What are the main greenhouse
gases in troposphere causing global
warming?
What is the
Green House
Effect? What
are the main
gases that
cause the
effect?
17.3 Temperature Controls
What are the 6 things causing
Temperatures to vary?
1. Land (low specific heat capacity) heats more
rapidly and to higher temperatures, also cools
more rapidly and to lower temperatures.
Deserts cold at night hot during day
2. Water (high specific heat capacity) heats up
slowly and cools down slowly
Mean Monthly Temperatures
for Vancouver and Winnipeg
Which is close
to the ocean?
What is the effect?
Which is furthest
from the ocean?
What is the effect?
17.3 Temperature Controls
3. geographic setting
How does geographic position
influence these two cities?
17.3 Temperature Controls
4. altitude
How does altitude
influence temperature?
17.3 Temperature Controls
5. Cloud cover high albedo therefore reflect back
to space a significant portion of suns energy
• Albedo is the fraction of total radiation that is
reflected by any surface.
How does cloud albedo affect these two pictures?
17.3 Temperature Controls
World Distribution of Temperature
 Isotherms lines on a weather map that
connect points of the same temperature
What do you notice
about the isotherms
in the north
compared to the
south?