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Questions of the Day
• Describe how wind is created.
• What happens to air pressure as I hike
up a mountain?
• What instrument measures air
pressure?
Global and Local Winds
Air Movement
•Wind is the movement
of air caused by
differences in air pressure
•The greater the
difference, the faster the
wind moves
Air Pressure
•Differences in air pressure
are caused by the uneven
heating of Earth
•Uneven heating produces
pressure belts which
occur every 30° latitude
Pressure Belts
•As warm air rises at the
equator and moves toward
the poles, it cools
•As it cools, some of the air
sinks around 30° north
and south of the equator
Pressure Belts
•At the poles, cold air
sinks and moves
towards the equator
•Around 60° north and
south, the air begins to
heat up and rise
Coriolis Effect
• Because the Earth rotates, and consists of
a mixture of land and sea, the Coriolis
Effect exists
• The Coriolis Effect is the movement of
particles (such as air) to the right in the
Northern Hemisphere
• How about the South?
– They move to the left
Coriolis Effect
Coriolis Effect
• Coriolis Effect – Rotation of the Earth causes moving air
and water to change directions
• Northern Hemisphere winds curve to the right
• Southern Hemisphere winds curve to the left.
http://www.youtube.com/watch?v=mcPs_OdQOYU
Global Winds
•The combination of pressure
belts and the Coriolis Effect
cause global winds
•These are polar
easterlies, prevailing
westerlies, and trade
winds
Warm Moist Air Rises
Cool Dry Air Sinks
Warm Moist Air Rises
Cool Dry Air Sinks
Cold Moist Air Rises
Cool Dry Air Sinks
Warm Moist Air Rises
Cool Dry Air Sinks
Cold Moist Air Rises
Very Cold Air Sinks
Cold Moist Air Rises
Cool Dry Air Sinks
Warm Moist Air Rises
Cool Dry Air Sinks
Cold Moist Air Rises
Very Cold Air Sinks
Very Cold Air Sinks
H
Cold Moist Air Rises
L
H
Cool Dry Air Sinks
L
Warm Moist Air Rises
Cool Dry Air Sinks
Cold Moist Air Rises
Very Cold Air Sinks
H
H
L
H
L
H
L
H
L
H
Wind Moves
from HIGH
to LOW
Objects are
deflected to
the
RIGHT in the
Northern
Hemisphere
Polar Easterlies
•Wind belts that extend from
the poles to 60° latitude
•Formed from cold sinking air
moving from the poles
creating cold
temperatures
Prevailing Westerlies
•Wind belts found between
30° and 60° latitude
•Flow towards the poles
from west to east carrying
moist air over the United
States
Trade Winds
•Winds that blow from
30° almost to the
equator
•Called the trade winds
because of their use by
early sailors
Doldrums
•Located along the
equator where no
winds blow because
the warm rising air
creates and area of low
pressure
Horse Latitudes
• Occur at about 30° north and
south of the equator where
the winds are very weak
• Most deserts on the Earth are
located here because of the
dry air
Jet Stream
•The jet streams are
narrow belts of high
speed winds that blow
in the upper troposphere
and lower stratosphere
•Separates warm air
from cold air
Jet Streams
• Jet Streams form at
•
latitudes where wind
systems come
together
High speed westerly
winds form high
above the surface
What brings certain weather phenomenon?
El Nino
• occurs when the surface
temperature rises above the
normal water temperature in
the Equatorial Pacific Ocean
creating more humidity in the
atmosphere
• Known to increase number of
hurricanes
• Occur more frequently (every
3-7 years)
La Nina
 occurs when the surface
temperature falls below the
normal water temperature in
the Equatorial Pacific Ocean
creating a more dry
atmosphere
 Known to create drought
conditions
Local Winds
•Generally move short
distances and can blow
in any direction
•Caused by geographic
features that produce
temperature differences
Local Winds
• Cover short distances
• Blow from any direction
• 2 Types of Local Winds
– Sea Breezes- from sea to land
– Land Breezes – from land to
sea
Sea Breezes
• High pressure is created over
the ocean during the day and
low pressure over land due to
uneven heating
• Air moves from the ocean to
the land creating a sea
Land Breezes
• Low pressure occurs over the
ocean during the night and
high pressure over land due to
the uneven heating of earth
• This causes wind to move from
the land to the ocean creating
a land breeze
What’s the difference?
Question 1
•What causes winds?
Answer
•Winds are caused by the
uneven heating of
Earth’s surface, which
causes pressure
differences
Question 2
•What are the three types
of global winds?
Answer
•Polar Easterlies
•Westerlies
•Trade Winds
Question 3
•What is the difference
between a land breeze
and a sea breeze?
Answer
•Sea breezes occur during
the day when the land is
warmer than water and a
land breeze occurs at
night when the water is
warmer than land
Global Wind Patterns Flipbook
• Cut out the outline map. Set aside.
• Fold 2 sheets of paper long ways in half
• Cut both pieces in half long ways along
the fold lines. Keep three strips of paper.
• Stack the papers on top of each other.
Global Wind Patterns Flipbook
• Shift the papers over so that there is
approximately one cm between each one
• At the middle of the stack fold the papers
under so that each tab is about a cm
across
• Staple
• Glue outline map on front tab
Global Wind Patterns Flipbook
• Fill in an label the global wind patterns using
the following colors. Use the same colors when
writing the name of the wind on the tabs
• Doldrums-red
• Tradewinds-orange
• Horse latitudes-yellow
• Westerlies-green
• Polar easterlies-blue
Global Wind Patterns Flipbook
• Draw arrows using black to indicate the
directions of the winds movement due to
the Coriolis Effect
• On the tabs above each item (above the
terms) give a detailed description of the
concept