Download 1_TheAtmosphere - Westmount High School

The Atmosphere – extends more than
10 000 km above the Earth’s surface
The Atmosphere
Definition: It is the layer of air surrounding the
Earth.
• It is made of gases that are essential for life!
1. They block UV and other dangerous rays from
the sun.
2. They ensure stable climate on Earth.
3. Include: 02 = For Cellular Respiration
CO2 = For Photosynthesis
The Atmosphere
•
•
•
The air is a mixture of gases,
especially nitrogen and
oxygen, that makes up the
atmosphere!
Proportions will changes at
high altitude (100 km)
Relative humidity: the
proportion of air that is made
up of water. It is responsible
for cloud formation and
precipitation. It can reach 4%
of the air volume.
Pollen!
Composition of the
atmosphere at low altitude
The Atmosphere
• Divided in 5 layers.
• The higher the
altitude, the fewer
the air particles in
the atmosphere
(density decreases).
Layer 1 – Troposphere (0 to 15 km)
• Include most meteorological phenomena.
• Include storms and cloud formation.
• The temperature drops of 6.5°C with every 1000m.
Layer 2 – Stratosphere (15 to 50 km)
• This is where ultraviolet rays are absorbed
(ozone layer)
• In this layer, temperature increases with altitude.
• Air particles are increasingly rare!
Layer 3 – Mesosphere (50 to 80 km)
• The coldest layer of the atmosphere.
• The temperature decreases with altitude.
• Almost no air!
It can reach -80°C
Layer 4 – Thermosphere (80 to 500 km)
• It absorbs much of the sun’s rays.
• The hottest layer : temperature can reach 1800°C
at high elevation.
• Celestial bodies such as meteors burn in this layer
(ex: shooting stars).
• Polar auroras (aurora borealis) form in this layer.
Layer 5 – Exosphere (500 km and more)
• Almost completely empty.
• Almost no air; we can’t gauge its temperature.
• This is where we put communications satellites.
Atmospheric Pressure
• It is the pressure of the air.
• Air is a gaseous mixture that contains particles that
are constantly colliding with one another.
• At sea level, the average atmospheric pressure is
101.3
kilopascals (kPa).
• 1 kilopascal =
100-kg mass
on an area of one
square meter.
• CLIP
1.2 Atmospheric Circulation
• Definition: the global-scale movement of the
layer of air surrounding the Earth.
• It rises in the atmosphere above the warm
humid regions of the equator and descends
over cold and dry regions of the poles.
• This phenomenon of CONVECTION helps
distribute the solar energy the Earth receives.
Coriolis effect – READ PAGE 226
• Due to the rotation of the Earth,
currents are deflected to the
right in the northern hemisphere
and to the left in the southern
hemisphere.
• This effect is greatest at the poles
and least at the Equator because
of Earth’s near spherical shape.
• http://www.youtube.com/watch?v=mc
Ps_OdQOYU
Coriolis effect
• CLIP!
• CLIP 2 !
Air Masses
• Definition: large expanse of the atmosphere
with relatively uniform temperature and
humidity.
Cold air = dense
SINKS!
Warm air = less dense
RISES!
In Québec
• Our climate is subject to the effect of warm air
masses from tropical regions and cold air
masses from polar regions. Air masses do not
mix!
Precipitations!
Front: the line where the two masses meet!
COLD FRONTS
• When a mass of cold air meets a mass of warm air!
• Warm air rises rapidly, in a sharp ascent and then
cools. Condensations = CLOUDS (CUMULUS)
CUMULUS
• Definition: Puffy clouds which often produce
wind and heavy rain.
WARM FRONTS
• A warm front forms when a mass of warm air
moves toward a mass of cold air, rising gently above
cold air and creating clouds in stratified layers.
NIMBOSTRATUS
• Light clouds in stratified layers. Associated with
slow to disparse showers.
ANTICYCLONE – SYMBOL: H
• Definition: Area of atmospheric circulation
surrounding a high-pressure centre. The air turns
clockwise in the Northern Hemisphere and
counterclockwise in the Southern Hemisphere.
DEPRESSION – SYMBOL: L
• Definition: Area of atmospheric circulation
surrounding a low-pressure centre. The air turns
counterclockwise in the Northern Hemisphere
and clockwise in the Southern Hemisphere.
L
In the Northern Hemisphere!
Depression
Anticyclone
Weather!
Anticyclone
Depression
-Clear sky
-Clouds
-Stable weather
-Precipitation
-Dry
-Sunny
-Cold in the winter
Cyclones!
• Also known as hurricanes or typhoons
• Definition: Tropical storm characterized by
violent winds revolving around an area of low
pressure.
• Winds can reach 360 km/h!
• Diameter of up to 800 km
CLIP 1
CLIP 2
1.3 The Greenhouse Effect
• Definition: Natural process that allows the Earth
to retain some of the heat it receives from the
sun.
• Greenhouse gases : water vapour H20, carbon
dioxide CO2, methane CH4 and nitrous oxide N2O.
3 Step Explanation !
• 1 – Most of the sun’s rays that reach Earth are
absorbed by the ground.
• 2 – Once heated, the ground emits INFRARED
rays into the atmosphere. Some pass the
atmosphere and are lost in space.
• 3 – Greenhouse gases trap some of those
INFRARED rays and send them back to Earth.
How does it work?
1.4 Energy Resources
WIND ENERGY
• Definition: Energy that can be drawn from
the wind.
• HUGE: up to 120 m in height
PROS
• RENEWABLE
• No greenhouse gases
• No acid rain
• No destrcution of ozone
layer
CONS
• Not nice (esthetics)
• Unpredictable winds
• Energy cannot be stored
• Noisy
CLIP 1
CLIP 2
One megawatt
wind turbine
=
150 to 300
households