Section 1-3: Wind
Name: ___________________________________
WINDS
WIND IN THE
ATMOSPHERE
Lesson 3-3
Wind can be defined as the movement of air from
place to place.
Winds are caused by differences in air pressure
due to unequal heating of the atmosphere and the
Earth’s surface.
Because of this unequal heating, cooler, denser air
from a high pressure area moves into a warmer,
less dense, low pressure area.
High Pressure
MOVIE: “I WANT TO KNOW:
WIND
UNEQUAL HEATING
While watching this video, answer the following
questions:
What causes winds?
Why is wind important?
Low Pressure
OF
EARTH
Due to the Earth’s tilt of 23.5º, the Sun’s ray hit it at
different angles and this causes the planet to hit
differently in different areas.
SEA BREEZES
TYPES OF WINDS
Click on the animated mills
to see categories!
6th Grade Science–Mr. Mayorga (104)
Air flows from sea to land (named after place of
origin)
Occur during the day because the ground is hotter
than the ocean
The air above the ground is warmer
The warmer air above the ground is less dense
This area of warmer air above the ground has a
lower air pressure
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Section 1-3: Wind
LAND BREEZES
Air flows from land to sea
Occur at night because the land cools off faster than
the ocean
The air above the ground is cooler
The cooler air above the ground is denser
The area of cooler air above the ground has a
higher air pressure
PHYSICAL MECHANISMS
THAT CAUSE MONSOONS
MONSOONS
Summer or Ocean
Monsoon:
June through
September
From southwest
Warm, moist
winds flow from
the Indian Ocean
into Asia
6th Grade Science–Mr. Mayorga (104)
From the Arabian
term Mausin,
«seasonal winds»
Occur mainly in the
Indian subcontinent
and are caused by the
heating and cooling of
Asia, the Arabian and
Indian Oceans
MONSOON TYPES
Differential heating between the land and oceans
Coriolis forces due to the rotation of the Earth
And the role of water which stores and releases
energy as it changes from liquid to vapor and back
(latent heat)
MONSOON TYPES (2)
Name: ___________________________________
Winter or Land
Monsoon:
September
through March
From northeast
Cold, dry winds
flow from Asia
into the Indian
Ocean
THE CORIOLIS EFFECT
As Earth rotates, the
Coriolis effect turns
winds in the
Northern
Hemisphere toward
the right.
2
Section 1-3: Wind
CORIOLIS EFFECT
The apparent shift or deflection of the air moving
above the surface of the Earth due to its rotation
Northern Hemisphere: Turn right relative to the
Earth’s surface
Southern Hemisphere: Turn left relative to the
Earth’s surface
Name: ___________________________________
EARTH’S GLOBAL WINDS
Doldrums
Trade Winds
Prevailing
Westerlies
Polar Easterlies
Jet Streams
EARTH’S GLOBAL WINDS
DOLDRUMS
Are also known as the Equatorial Belt of Calms
Roughly between 0°—5° N and S of the equator
Low-pressure calm latitudes
Have hot, humid, and slowly rising air, which creates little
to no wind
A series of
wind belts
circles Earth.
Between the
wind belts are
calm areas
where air is
rising or
falling.
DOLDRUMS (2)
Rainfall in this pressure belt area is concentrated in
the rising air of the ITCZ.
Are also known as the Intertropical Convergence
Zone (ITCZ) because the winds from the two
hemispheres converge here
6th Grade Science–Mr. Mayorga (104)
3
Section 1-3: Wind
Name: ___________________________________
TRADE WINDS (2)
TRADE WINDS
Global winds that move between the horse
latitudes and the equator (17-21 kmph)
Northern Hemisphere: Northeast Trades
Southern Hemisphere: Southeast Trades
Trade winds form as the equatorial air cools and
begins to sink back to the Earth’s surface (circa 30° N
and 30° S latitude).
Horse Latitude
(30ºN)
Equator (0ºN)
The descending air warms as it is compressed creating a
high pressure area with hot, dry surface air.
The air then begins to flow back to the Equator—Trade
Winds.
30° latitudes are called horse latitudes because at
sea, the hot, descending air creates weak winds.
Horse Latitude
(30ºN)
TRADE WINDS (3)
TRADE WINDS (4)
This section usually has clear skies and very little
rain. On land, it accounts for the world’s great
deserts–the Sahara, the Arabian, etc.
These are particularly strong winds that move
between 30º through 60º North and South of the
Equator.
Due to the Coriolis effect, they always seem to
move from west to east, hence their name.
Prevailing
Westerlies
Trade winds were used by sailors coming to the
New World. Today, they are used by pilots to
increase speed and save fuel when flying east to
west.
PREVAILING WESTERLIES (2)
PREVAILING WESTERLIES
Prevailing Westerlies are caused by cool, sinking air
from the horse latitudes that continues to move
toward the poles.
These winds are responsible for many of the
weather movements across the US and Canada.
60º
30º
0º
Prevailing
Westerlies
30º
60º
6th Grade Science–Mr. Mayorga (104)
4
Section 1-3: Wind
Name: ___________________________________
POLAR EASTERLIES
Winds that blow between 90° to 60° latitudes
Extremely cold , weak winds flowing from the poles
towards the equator
Due to Coriolis Effect they seem to travel from east
to west
Cause many weather changes in USA
JET STREAM
JET STREAMS
CONT’D
Flow from west to east at altitudes above 12 km (8
mi) and cause air masses to spread out producing
low pressure areas; centers of local storms
Wander up and down as they circle the Earth
Speeds can reach 180 km/ph in summer, and 220350 km/ph in winter.
The two most important jet streams are the Polar
Jet Stream and the Subtropical Jet Stream.
Jet streams were first
discovered in the 1940’s
Narrow belts of strong,
high-speed, highpressure air that moves
in the upper troposphere
affecting the
atmosphere below them
JET STREAM
CONT’D
Pilots use jet streams to increase speed and save
fuel when flying west to east.
The jet streams are high-speed bands of winds
occurring at the top of the troposphere.
MEASURING WIND
The surface wind direction and speed are usually
measured at about 10 meters above the ground.
Wind direction is measured using a wind vane and
a windsock.
Wind speed is measure using an anemometer.
6th Grade Science–Mr. Mayorga (104)
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