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TRANSCRIPT
L AY E RS O F T H E AT MO SP HE RE
Atmosphere
Why is the atmosphere divided into 5 different layers?
The atmosphere is divided into five different layers
because the atmosphere is not uniform, its
properties change with altitude.
Two properties change with altitude, the AIR
PRESSURE and the AIR TEMPERATURE
Lets look at each layer individually.
ATMOSPHERE
The earth is surrounded by a
blanket of air that we call
atmosphere. The atmosphere
is considered in terms of layers, or regions, arranged
like spherical shells above the
surface of the Earth.
COMPOSITION OF THE ATMOSPHERE
The atmosphere is primarily composed
of nitrogen (N2, 78%), oxygen (O2,
21%), and argon (Ar, 1%). A
myriad of other very influential
components are also present which
include the "greenhouse" gases or ozone (0 -
0.01%), carbon dioxide (CO2,
0.033%).
LAYERS OF THE ATMOSPHERE
There are 4 layers in the atmosphere
They are the troposphere, mesosphere, thermosphere, and stratosphere
TROPOSPHERE
This is the layer that is closest to the
surface of the earth
It’s elevation ranges from 0 to 10 km
This is where all plants and animals
live and breathe
Where weather takes place
Air is mixes
Temperature decreases with
altitude
Ozone Layer
•Pale blue gas with a strong odor.
•90% of all ozone is found in the stratosphere
•10% is found in the troposphere
•Ozone is extremely important because it is
the only gas that absorbs ultraviolet
radiation from the Sun and protects the
surface of the Earth and people from the damaging effects of
UV rays
Stratosphere
This layer sits on top of the
troposphere
It’s elevation ranges from 10 km
to around 25 km
This layer contains the ozone layer, which protects us
from harmful sunlight
People can not breathe in this
layer.
MESOSPHERE
This layer is above the stratosphere.
It’s elevation ranges from 25 to 100 km
Temperature decreases with altitude
This is where we see "falling stars" – meteors burning up as they fall
to Earth
The mesosphere is the coldest layer of the
atmosphere.
Radio waves are reflected back to earth
in the mesosphere.
Ionosphere
An extension or a part of the
thermosphere. So technically, the
ionosphere is not another
atmospheric layer.
Free electrons and ions tend to recombine
THERMOSPHERE
This is the highest layer of
the atmosphere
It’s height ranges from 100
to 400 km
This is where most small
meteorites burn up and is
also the location in the
atmosphere that the
northern lights occur
(aurora borealis)
Layer of the atmosphere
which is first exposed to
the Sun's radiation and so
is first heated by the Sun.
The air is very thin
The temperature
dependent on solar activity.
Exosphere
Highest layer of the atmosphere. The air is very
thin here
Atoms and molecules
escape into space
Label the layers of the atmosphere below:
1.TROPOSPHERE- contains dust, moisture, weather.
2.STRATOSPHERE - contains protective ozone
3. MESOSPHERE- coldest layer
4. THERMOSPHERE- contains auroras, high temperature but low heat
5. EXOSPHERE-
The highest layer of the atmosphere where commercial satellites are located.
Weather & Climate
Weather & Climate Definitions
Weather- “the state of the atmosphere with respect to heat or cold, wetness or dryness, calm or storm, clearness or cloudiness”.
Climate – “the average course or condition of the weather at a place usually over a period of years as exhibited by temperature, wind velocity, and precipitation”
What causes Weather?
All elements of weather are the direct result of energy from the sun.
The sun’s rays hit earth and the land absorbs the heat unevenly.
This uneven heating causes changes in weather.
What does weather include?
Air temperature
Cloud cover
Amount of sunlight
Relative humidity
Precipitation
Wind speed
Wind direction
Temperature
Temperature is amount of heat in a substance. Expressed in degrees Fahrenheit or Centigrade
(Celsius)
Temperature is measure by an instrument called a thermometer.
A Bunch of Hot Air.
Cold air contracts or sinks.
The air molecules get closer together, which makes the air heavier or more dense.
Hot air expands or rises. The molecules get further apart, become less dense and they get lighter.
Air Circulation
Since warm air rises, the upper part of the room is the warmest. The coolest part of the room would be closer to the floor.
Wind Spiral
Why is the spiral able to turn?
The hot air “rising” is turning the spiral.
Wind
Wind is moving air in the atmosphere.
Air is always moving from high pressure to low pressure.
The strongest winds are tornadoes, the air pressure is extremely low.
How to measure wind speed
Wind speed is measure in kilometres per hour (kph). We use a device called an anemometer.
Wind Direction is always stated in terms of where the wind is coming from.
Measuring Wind Direction
Wind Sock
Weathervane
Humidity- Moisture in the Air
The sun heats up the water on land and causes evaporation.
The moisture that is in the air is called humidity.
Saturated is when the air has too much moisture and cannot hold anymore.
The Water Cycle
The sun heats up the water- evaporation
The water vapor (gas) condenses into clouds
The clouds become saturated and precipitation is the result.
The precipitation pools in lakes, oceans and rivers. Waiting to evaporate again.
Relative Humidity
It is the ratio of how much moisture is in the air and how much the air can hold.
50% humidity means the air is holding 50% moisture
Precipitation
When there is too much moisture, the water will fall as precipitation.
Precipitation will fall in two main forms: rain or snow depending on the temperature of the air through which the moisture will fall.
Other forms of precipitation are sleet and hail.
Forms of Precipitation
Snow
If the air is cooled below the freezing point of water, the condensing moisture is quickly freeze into ice crystals.
The ice crystals join to make snowflakes
Snowflakes are always six sided.
Rain
When droplets of moisture join together becoming heavy enough to fall to the ground.
Hail
Formed in cumulonimbus (storm) clouds. They are frozen droplets of moisture.
Sleet
When falling rain starts off in warmer air, but passes through air below freezing, the rain drops cool and freeze onto surfaces when they hit the ground.
Facts on Precipitation
It takes 10 centimetres of snow to make one centimetre of rain.
Dew is moisture in the air cools off at night. In the morning it is found on everything. In colder temperatures, dew is frost.
Air Pressure
The force that is applied on everything on the Earth caused by the weight of the air.
Air particles are mobile, the exert pressure on objects. High air pressure brings warm, dry air. Low air pressure
brings rain or moisture Air pressure can change quickly, ie- when a storm comes
in. There are three factors that affect air pressure: altitude,
air mass temperature and the amount of moisture in the air.
A Barometer is used to measure air pressure.
Clouds
Clouds come in many shapes and forms.
Some are high in the sky, while others are so low they touch the ground.
No matter what shape or elevation, clouds form the same way, by having water vapor condense onto small solid particles like dust, sea salt, and pollution
Clouds
Clouds serve several important functions.
They provide rain and snow.
They also help retain heat, so it doesn’t escape quickly back into space.
On hot days, clouds provide shade
Can you identify these clouds?
Seasons
The Earth orbits around the sun.
The Earth tilts on its axis 23.5 degrees.
The area of the Earth, that heats up more, is closer to the sun.
Seasons
When Canada is tilted away from the sun, it is winter.
When Canada is tilted towards the sun, it is summer.
Spring and Autumn are the in between orbits.
Factors that influence weather in different areas.
Land Elevation
Location- lattitude and longitude
The sun
Cloud cover
Air pressure
Earth’s orbit (seasons)
METEOROLOGY
Known as weather science. The term comes from two Greek words meaning
‘high in the air’ and ‘knowledge’.
TEMPERATURE
Is a measure of how fast air molecules are moving.
High Pressure
Higher pressure than what is normal for that altitude.
The air becomes more dense and sinks, forming regions of high pressure.
What do you notice about the air in this region?
Brings clear skies and fair weather. The sinking cold air warms as it does so
and becomes stable.
Low Pressure
• A low pressure region (depression or cyclone) is caused by rising air.
• Clouds, rain, and very strong winds occur.
• Why do you think that is?
CLOUDS
Precipitation
Rain - Water falling in drops from vapour condensed in the atmosphere
Drizzle - Very light rain; stronger than mist but less than a shower
Dew - Water that has condensed on a cool surface overnight from
water vapour in the air
Snow - Precipitation falling from clouds in the form of ice crystals
Sleet - Partially melted snow (or a mixture of rain and snow)
Hail - Precipitate as small ice particles
Frost - Ice crystals forming a white deposit (especially on objects outside)
Cloud Types
Picture taken from:
http://commons.wikimedia.org/wiki/File:Cloud_types.jpg
Temperature & Humidity
• Temperature - Air higher in pressure is usually cooler air and air lower in pressure is usually warmer air.
• What happens when the two meet?
• Humidity - How much water is in the air over how much water could fit in the air (right before the water begins to condense out of the air).
• Dew point - Temperature at which the moisture saturates the air is the dew point.
Relative Humidity
is a measure of the amount water vapor that is present compared to the amount
that could be present at a specific temperature.
Wind
Pressure and temperature are directly related, wind can be thought of simply as air moving from one temperature or pressure to another area. The greater the difference in pressure or temperature
between two areas, the stronger the wind that blows between them will be.
SURFACE WINDS
Air that expands, becomes less dense, and gets pushed upward. Air at the equator is
heated by the rays of the Sun.
TRADE WIND (Tropical Easterlies)
Steady winds blowing from east to west above and below the equator
Westerlies and Easterlies
Prevailing Westerlies – wind blow from the west. These
winds form the boundary between cold air from the poles and
milder air closer to the equator.
Polar Easterlies – wind blow from the east. Near the poles,
cold, dense air sinks and flows away form the poles. It is
replaced by warmer air flowing in from above.
Breezes
Land Breeze – wind blowing from the land to the sea.
Sea Breeze – wind blowing from the sea to the land.
Mountain Breeze
– mountain cools rapidly than valleys. The cool heavy air on the mountainside then flows down into the valley. This is the chilly breeze you may feel in the evening.
Valley Breeze
– The air on the mountainside facing the sun therefore becomes warmer than the air over level land. With uneven heating causes a warm breeze to move up the slope.
Types of Clouds
Type Appearance Characteristics
Cirrus feathery
Fair weather clouds
Thin and curly
Consists of ice crystals because they are formed
under low temperatures at high altitudes
Cumulus
piled or heaped up/
puffy, like huge
towering columns
Heads of cauliflower with flat bottoms
Developed when rising columns of moist air are
cooled to the dew point temp.
Stratus spread out or
stretched in layers
Few hundred meters thick but may extend over
thousands of square kilometers.
Nimbus Rainy/ dark or
grayish clouds Any cloud that produces precipitation.
According to Height
Groupings according to Height in the Atmosphere Type
HIGH CLOUDS Mean lower level: 6000 m
1. Cirrus 2. Cirrostratus 3. Cirrocumulus
MIDDLE CLOUDS Mean upper level: 6000 m Mean Lower level: 2000 m
4. Altocumulus 5. Altostratus
LOW CLOUDS Mean upper level: 2000 m
Mean Lower level: close to the surface of the Earth
6. Stratocumulus 7. Stratus 8. Nimbostratus
CLOUDS OF VERTICAL DEVELOPMENT Mean upper level: that of cirrus clouds or higher
Mean Lower level: 500 m
9. Cumulus 10. Cumulonimbus