Download Air Movement

Air Movement
on Earth
Outline
– What is wind?
– What causes it?
– What are some common wind patterns?
• Surface winds
• Jet stream
• Sea and land breezes
• Earth is a rocky, inner planet with liquid water
on over 70% of its surface.
• Having two different types of surface (land
and water) strongly affects the wind produced
on Earth.
– Which surface heats up more quickly?
• Sand
– Which surface cools off more quickly?
• Sand
• Which areas of the Earth receive more direct
sunlight and therefore are hotter?
– Equator gets more direct light and is therefore
hotter
• Do all areas of Earth have the same amount of
sunlight all year long?
– No! More sunlight hours in summer, therefore it’s
hotter.
• Surface type (land or water) and temperature
(affected by direct/indirect light and hours of
sunlight) can cause an uneven heating of
Earth’s surface.
• As air molecules heat up, they move apart and
become less dense
– This is called low air pressure
Can you answer this?
Warm air rises because
it is less dense
Cold air sinks because
it is more dense
What is Wind?
• Wind is the movement of air from an area of
high pressure (cold) to an area of low pressure
(warm)
What areas of Earth will have colder
(higher pressure) air?
Air near
the poles
will be
colder
and
higher
pressure.
The high pressure air from the poles
will flow towards the low pressure
areas by the equator
• This causes wind
• But it doesn’t flow
in a straight line as
seen in this picture
• Why?
Wind doesn’t travel in a straight line
due to Earth’s rotation on its axis
• Wind (and
water) in the
Northern
Hemisphere
will turn to the
right
• Wind (and
water) in the
Southern
Hemisphere
will turn to the
left.
We see this spin in hurricanes
• N. Hemisphere
storms spin
counter
clockwise
• S. Hemisphere
storms spin
clockwise
In which hemisphere is this hurricane
occurring?
Northern Hemisphere, it’s
spinning is counter clockwise
This curving of the wind is called the
Coriolis Effect
• Does it affect the spinning of the water in my
toilet?
• No, the water in the toilet in not a large
enough body of water.
https://www.youtube.com/watch?v=rdGtcZSFRLk
Coriolis Effect on toilets?
Wind Patterns
• Earth’s surface with different surface materials
(land or water)
• Plus, the different amount of solar radiation
received (direct or indirect light, and hours of
light)
• Plus, the Coriolis effect
All add together to create distinct wind patterns
on Earth.
Common Wind patterns
• Polar
Easterlies
• Westerlies
• Tradewinds
• Doldrums
http://www.yout
ube.com/watch?
v=qh011eAYjAA
Global winds
over a year
Trade Winds were important to early
explorers and for trade routes
Jet Stream
• A strong belt of wind in the upper
troposphere.
• It flows from west to east.
• Pilots take advantage of this when they fly to
the East coast.
The jet stream is why we look to the
west to find out what type of weather
is moving our way.
Local Wind Systems
• Local areas near bodies of water experience
smaller scale wind patterns
Sea breeze
• During the day, air over the land is heated by
conduction.
• The warmer, less dense air rises
• The cooler (high pressure) ocean air moves
into the low pressure area, resulting in a sea
breeze
Land breeze
• At night, air over the land cools quickly.
• The cooler, less dense (high pressure) sinks
and moves towards the low pressure (warmer)
air over the water.
• Resulting in a land breeze.
Summary
• Warm air is less dense than cool air
• Differences in density (temperature) and air
pressure cause air movement- wind
• Coriolis effect causes the wind to turn
• Wind patterns are observed in different
lattitudes
• A wind pattern seen high in the troposphere is
the jet stream
• Sea breezes and land breezes are patterns of
air seen near bodies of water.
Review Videos
https://www.youtube.com/watch?v=RzSqhrn2dDM
Review of Wind
• http://earth.nullschool.net/
A visualization of global weather conditions forecast by
supercomputers updated every three hours (open in Google
Chrome) You can spin the globe and zoom in
• http://www.youtube.com/watch?v=6hD52H7rQak
The Sun as the driving force behind for wind and water
currents and earth’s temperatures