Download Atmosphere

Atmosphere
Why is it rainy, cold, and dark this
time of year?
Why is it rainy?
• To know why it rains so much in the PNW you
need to know about the atmosphere.
• Composition of Air
Layers of Atmosphere
Layers of Atmosphere
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Troposphere
Stratosphere
Mesosphere
Thermosphere
layers of atmosphere
felix baumgartner Red Bull Stratos
Layers of the Atmosphere
• The atmosphere is divided into five layers. It is thickest near
the surface and thins out with height until it eventually
merges with space.
• 1) The troposphere is the first layer above the surface and
contains half of the Earth's atmosphere. Weather occurs in
this layer.
2) Many jet aircrafts fly in the stratosphere because it is
very stable. Also, the ozone layer absorbs harmful rays from
the Sun.
3) Meteors or rock fragments burn up in the mesosphere.
4) The thermosphere is a layer with auroras. It is also where
the space shuttle orbits.
5) The atmosphere merges into space in the extremely thin
exosphere. This is the upper limit of our atmosphere.
Temperature
• The land and water absorb heat energy from
the sun.
• Some of this energy warms the atmosphere
above the surface.
• Earth’s surface heats up differently depending
on the time of day.
• Copy picture on pg. 201
Temperature
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Different substances heat faster or slower.
i.e. water heats up slower than land
Grass does not hold heat very well
Blacktop heats up fast and holds heat. It cools
down quickly at night.
Wind
• Forms from convection currents because
water and land heat up at different rates.
• Land heats faster, water slower.
• Winds can also change direction because the
Earth is spinning.
• This is called the Coriolis effect.
equator water experiment
heating land and water
Air Pressure
• We are at the bottom of an ocean of air
therefore air pressure is greatest at the
surface.
Air Pressure
• Air has mass, when gravity pulls on the mass
the air has weight.
• Air pressure is the weight of air pressing in all
directions.
• Air pressure is measured by a barometer.
weather and air pressure
Conditions to affect air pressure
• Water Vapor content
Moist air has lower pressure
• Temperature
Air gets warmer the pressure goes down
• Altitude
The higher the altitude the less pressure
Weather
• When air pressure changes, there will be a
change in weather.
• Rising air pressure = clear weather
• Falling air pressure = cloudy weather
weather for today
Humidity
• Air holds a lot of water vapor. Water vapor in
the air is called humidity.
• Water from oceans, lakes, rivers evaporate
into the air.
• When the air is cold you can sometimes see
the water vapor in the air. This is called fog.
• Humidity is measured with a hygrometer.
Precipitation
• Water vapor condenses to form liquid.
• Water droplets clump together to form drops.
• Clouds get heavy, drops fall to Earth because
of gravity.
• Rainfall is measured with a rain gauge.
Clouds
• Clouds form when water vapor in the
atmosphere condense and change to liquid.
• Clouds form in low air pressure.
• Three types of clouds
1. Cirrus (feathery or tufted)
2. Stratus (sheets or layers)
3. Cumulus( piled up)
Nimbo- means precipitation
cumulus
Stratus
cirrus
Nimbostratus
Cumulonimbus aka thundercloud
cumulonimbus
Recipe for a cloud
• Water vapor + low pressure + dust(nuclei) =
cloud
Weather Quickwrite
• Explain how temperature, air pressure, and
humidity can work together to form the
stratus clouds we see out there today.
Reasons why it rains a lot in the PNW
1. Cascade Mountain range- lots of runoff from
the glaciers on the mountains.
2. Puget Sound – keeps temperature cold in
summer, warmer in winter
3. Air from Canada is cold and moves down into
Washington.
Cascade Mountain rain shadow
Why is it cold and dark?
• The Earth is rotating in space at a rate of 1,000
miles per hour. This gives us approximately a 24
hour day.
• The Earth is revolving around the Sun through
space at an approximate speed of 66,000 m.p.h.
This gives us a 365 1/4 day year.
Why don’t we feel the speed?
• We don’t feel these speeds because we are
always moving at this speed. Just like we
don’t feel gravity and air pressure.
• Try looking at a car on a highway that is
traveling your same speed. If you just look at
the car it will appear like you are not moving!
Leap Year
• It takes 365.25 days for Earth to revolve
around the Sun.
• How many .25 does it take to equal 1?
• Therefore, leap year is every 4 years.
Reason for the Seasons
What causes Earth's seasons?
• The reason why it is cold and dark here in the
winter is because the Earth is tilted at 23.5°.
• The Sun hits the Earth differently depending
on the time of year.
• Days are shorter in the winter and longer in
the summer.
• We are the farthest from the sun in the
summer, and closer in the winter.
Moon
• The moon is 384,000 km or 235,000 mi. from
Earth.
• It takes 2 seconds for sunlight to reflect off the
moon and reach Earth.
• Moon has 1/6 the gravity compared to Earth.
• The pull of the moon causes tides in the
Earth’s oceans.
Phases of Moon
• Wax on wane off.
Day 1 of cycle
Day 14
How many days after the full moon?
How many days?
What phase is next?
Back to the start!