Download Our Atmosphere

OUR
ATMOSPHERE
The envelope of gasses that surrounds our
planet.
Atmospheric Composition
Our “air” is made up of:
-78% Nitrogen
-21% Oxygen
-0-4% Water Vapor
-0.93% Argon
-0.038% Carbon Dioxide
-0.01% Trace Gases
Carbon dioxide has increased
from 0.028% over the past 150
years. Why might this be
significant?
Our atmosphere from space
A SPECIAL COMPONENT OF OUR ATMOSPHERE OZONE
-Ozone molecules help to protect us from
the suns harmful UV radiation.
The ozone molecule (O3)
is created naturally in our
atmosphere when typical
oxygen molecules (O2)
gain an extra oxygen
atom.
LAYERS OF THE ATMOSPHERE:
Exosphere- the traditional boundary between Earth’s
atmosphere and outer space.
Last/Outer Layer
of our
Atmosphere
Thermosphere: The layer has extremely low density
which causes the temperature, temp is more than
1000°C.
This layer also contains the Aurora from solar wind!
Mesosphere: This layer actually decreases in
temperature.
This is the layer that protects us from meteoroids!
Stratosphere- Here temperature increases with altitude,
especially in the Ozone Layer. The UV absorption of UV
radiation in the ozone causes the temperature to rise.
Mesopause
The OZONE layer protects humans from the extremely
dangerous UV waves from the Sun.
Stratopause
Troposphere – The layer we live in. All weather happens
here. Temps can be as low as -60°C.
Atmospheric Layers
Tropopause
Surface of Earth
AIR PRESSURE
 Air
Pressure is the weight of the air pressing
down on you.
 Air Pressure and Elevation- As you go higher
in elevation, the air molecules are more
spread out, therefore the air is less dense.
Also, there is less air above you being pulled
down on you by gravity.
 Air pressure and Weather:
Sunny Weather= High Pressure (approx the
weight of a school bus!)
Cloudy/Rainy Weather = Low Pressure (approx
the weight of a Volkswagen beetle)
Why don’t humans crush if we are always under such
extreme pressure?
Air Pressure is measured
with a barometer, in
millibars (mb)
PRESSURE-TEMPERATURE-DENSITY RELATIONSHIP
Imagine a closed container with a fixed amount of gas…..
-Air pressure and temperature: As temperature increases, so
does pressure due to the increased rate of movement of the
gas particles.
-Air pressure and density: As density increases, so does
pressure because more molecules are being crammed into a
given space.
-Temperature and density: As temperature increases,
molecules get more energized and spread out decreasing
density.
HEAT TRANSFERSTHE WAY HEAT IS EXCHANGED ON EARTH.
Radiation: The direct transfer of heat
through the air.
Examples: sunlight, heat given off from a
fire or stove
Conduction: The transfer of heat from one
object to another.
Example: heat from the hot pot directly to
your hand, the pot directly heating the
water.
Convection: The circulation of heat
through a liquid or gas.
Example: warm air rising, a boiling pot of
water circulating, lava lamp.
Why does warm air rise?
These inversions
occur as land cools
very quickly and
cold air gets
trapped under warm
air.
In highly populated
areas, this can
become a problem
because pollution
can get trapped in
the cold air near
Earth’s surface.
TEMPERATURE
INVERSIONS
An increase in temperature with height
in an atmospheric layer. Normally, an
increase in height decrease causes a
decrease in temperature.
WIND – 2 types: local and global
-All winds are caused by pressure differences between to
masses of air. The air always tends to flow from high
pressure (or density) to low pressure (or density) just like
carbonation escaping a freshly opened bottle of soda).
These pressure differences are caused by the unequal heating of
Earth’s surface.
Local wind: These are short
term winds that move over
small distances and change
from day to day or even hour
to hour. (This is what you
typically think of when you
think of wind)
Global Winds: These are longterm movements in Earth’s
atmosphere that travel long
distances and always in the
same direction.
Think about temperature
differences (compare the
equator and the poles) and
why these winds are always
moving in the same direction.
HUMIDITY – THE AMOUNT OF WATER VAPOR IN THE
ATMOSPHERE AT A GIVEN TIME.
-Saturation: when the amount of water vapor in
the air has reached its maximum amount.
-Relative Humidity: The amount of water vapor in
a volume of air relative to the amount of water
vapor needed for that volume of air to reach its
saturation point.
For example, any saturated volume of air has
100% relative humidity.
If the air only contains half of the water vapor
needed for it to be saturated, it has a relative
humidity of 50%.
Cirrus tell that
there will be a
storm in a
couple of days
Fair
sunny
weather
These are the
only vertical
clouds and
are the huge
thunderstorm
and tornado
clouds.
Rain but not
thunderstorms
Flat/Low
overcast
clouds
Dew point is the temperature at which the air can no longer hold all of its
water vapor, and that vapor begins to condense into liquid water.
Shape
-Cirrus means curly or
thin.
-Stratus means layered.
-Cumulus means lumpy
or piled up.
Precipitation
Clouds containing
precipitation will
have the word
Nimb somewhere
in the name.
CLOUD
NAMES
Height
-Cirro are clouds above
6,250 meters.
-Alto clouds are between
1,875 and 6,250 meters.
-There is no prefix for
clouds below 1,875
meters.
Cloud Formation- clouds form by tiny water droplets attaching to dust particles in the sky.
Eventually the drops will build up on the dust until it becomes heavy enough for gravity to pull it to the
Earth’s surface as precipitation.
1. Evaporation fills the air with water vapor (gaseous water)
2. Air rises away from the surface, carrying the moisture upward.
3. As it rises, the temperature drops causing the water vapor to condense into tiny
droplets.
4. Water molecules attach to condensation nuclei (tiny dust particles that cloud
droplets form around).
5. Coalescence - The droplets continue to grow in size as condensation continues.
Most droplets will eventually collide with another droplet, increasing size.
6. Once they become heavy enough, gravity will pull them to the ground as
precipitation.
Cloud Formation Time Lapse
Types of Precipitation
A.
Rain- liquid precipitation
B.
Sleet- frozen ice pellets (less than
5mm)
C.
Freezing Rain- comes down as a
liquid by freezes on contact leaving
a glaze of ice.
D.
Snow- frozen, six-sided crystals.
E.
Hail- (only forms in cumulonimbus
clouds) ice pellets that circulates
vertically in the clouds and forms
layers as it grows bigger.
Supercooling – The process by which
a substance drops below its freezing
point without turning into a solid.
http://dsc.discovery.com/search/results.html?query=hail
The Water Cycle