Download 1. Weather Introduction

WEATHER
Wind
Pressure
Do Now
 What produces weather?
 Where on Earth is sunlight received more
directly? Indirectly?
 How is heat energy from the sun transferred
on earth and in the atmosphere?
Answers
 Weather is produced by the uneven heating
of earth’s atmosphere (specific heat)
 Earth receives more direct sunlight at the
equator and more indirect sunlight at the
poles
 Heat energy from the sun is transferred on
earth and in the atmosphere via
– 1. Conduction – atmosphere that touches
earth’s surface
– 2. Condensation – releases stored heat (540
calories) when clouds form
– 3. Convection – density causes differences
in air pressure which it turn cause air to
move in convection currents
 Hot air rises, expands – cools
 Cool air sinks or descends, compressed –
warms (Mountains and clouds/precipitation)
Pressure – weight of air
DIFFERENCES IN AIR PRESSURE ARE CAUSED PRIMARILY BY
UNEQUAL HEATING OF EARTH’S SURFACE
 Increase density, increase pressure
 Increase temperature, decrease pressure and density
 Increase altitude, decrease pressure
 Increase water vapor content, decrease pressure &
mass
 Measured by a barometer
 Isobars = lines of equal pressure
Pressure and Density
Decrease with
ALTITUDE
What weighs more????
Demo
 Materials:
– Petri dish
– Aluminum spheres
– Plastic spheres
– Scales
Water vapor replaces other air molecules that
are heavier
MOIST AIR WEIGHS LESS
Isobars
 Meteorology notes
 Practice identifying a high pressure and low
pressure areas
 General Rules for making isolines
 Isobars/isotherm practice…
Wind speed is DIRECTLY related
to the pressure gradient
Closer the isobars
Greater the pressure gradient
Greater the wind speed
Meteorology Note Packet
 Smart notebook file
 Land/Sea Breeze animation and diagram
Describe the differences in these 2
diagrams (arrows = wind/breeze)
 Top
– Wind coming from
ocean to land
– Day time
 Bottom
– Wind coming from
land to ocean
– Nighttime
Land and Sea Breeze Animation
 Land and Sea Breeze Animation
Sea Breeze
Sea Breezes
 Daytime
 How does the speed at which land and water heat
up differ?
 Land heats up faster than water (Specific Heat)
 Where is the high pressure?
 Over the ocean
 Where is the low pressure?
 Over the land
 Which way does the wind blow?
 From the ocean to the land
 Sea Breeze
Sea Breeze
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Land Breeze
Land Breezes
 Nighttime
– How does the speed at which land and water
cool differ?
 Land cools down faster than water (Specific Heat)
– Where is the high pressure?
 Over the land
– Where is the low pressure?
 Over the water
– Which way does the wind blow?
 From the land to the ocean
 Land Breeze
WIND – Horizontal movement of air
parallel to earth’s surface due to
pressure differences
 HIGH pressure to LOW pressure
 Coriolis Effect kicks in
Right in Northern Hemisphere
Left in Southern Hemisphere
 Winds named for the direction from which they
come
Coriolis Effect
Coriolis Effect Animation
Winds and Coriolis in N Hemisphere
 Blow out of High pressure systems and into
low pressure systems
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WIND MOVES
CLOCKWISE OUT
OF THE HIGH
WIND MOVES
COUNTERCLOCKWISE
INTO THE LOW
If earth did not
rotate, we would
have 1 big
circulation cell in
each hemisphere
High
pressure
at Poles
Low
Pressure
at equator
3 convection cells due to rotation,
and unequal heating due to tilt
WINDS AND CONVECTION CELLS
CAUSED BY DIFFERENCES IN AIR
PRESSURE
WINDS NAMED FOR THE DIRECTION FROM WHICH
THEY COME
Low Pressure – convergence 0° and 60 °N and S
High Pressure – divergence 30° and 90° N and S
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JET STREAMS – EASTERLY MOVING AIR
If the Jet Stream moves south – it’s colder
If the Jet Stream moves north – it’s warmer