Transcript 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.
Tropopause
The OZONE layer protects humans from the extremely
dangerous UV waves from the Sun.
Tropopause
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 air pressure increases,
so does density 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.
CORIOLIS EFFECT
• Coriolis Effect is the curving of
winds and ocean currents
due to the very fast rotation
of the Earth.
• Therefore, winds will not travel
in a straight line, they will
curve.
• This effect also causes storms
such as hurricanes to rotate
clockwise in the northern
hemisphere and counter
clockwise in the southern
hemisphere.
A.
B.
LAND AND SEA BREEZES
Land Breeze

Occurs during the evening

Land cools off yet water holds heat

Wind blows from land to sea
Sea Breeze

Occurs during the day

Land heats up quickly due to sunlight
and water takes longer to heat up

Wind blows from sea to land
Mountain Influence:
A. Leeward side of a
mountain
• The DRY side
• Usually a desert
• Rain shadow is an
area of little to no rain
Rainforest
Desert
INFLUENCE OF TOPOGRAPHY
B. Windward side of a
mountain
• The WET side
• Warm moist air raises
off the ocean
• Clouds and
precipitation form
• Mountains block the
moisture from
heading over the
mountain
• Usually a temperate
or rainforest
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
AIR MASSES:
An air mass is a body of air that carries the
characteristics from where it forms.
•
If it formed over water, it brings moisture.
•
If it formed over land, it is dry.
•
The air masses are carried across the US
by the Prevailing Westerlies. Therefore,
your weather comes from the west.
Weather for each air Mass:
•
cP- Continental Polar: Clear and cool
•
mP- Maritime Polar- Cool with rain or
snow
•
A- Arctic- Extremely cold and dry
•
cT- Continental Tropical- Hot and dry
(summer only and never reaches NJ)
•
mT- Maritime Tropical- warmer than
usually with precipitation
Fronts- The boundary at the front of an air mass
The front created depends on the characteristics of the air
mass..
http://www.physicalgeography.net/fundamentals/7r.html
Cold Front – Cold air moves in, forcing
warm air up. Intense precipitation and
storms are common with cold fronts.
Warm Front – Warm air moves in,
displacing the cold air. The warm air
rises gradually causing widespread
light precip.
Stationary Front – When 2 air masses
meet but neither advances. They are
usually similar in temperature. Causes
cloudy weather with light winds and
occasional precipitation.
Occluded Front – When a cold front
catches up to and takes over a warm
front. Warm air is forced up violently.
Typically causes strong winds and
heavy precipitation.