Download Winds

Winds
What is Wind?
The horizontal movement
of air from High pressure to
Low pressure.
• HL
Air moving up or down
(vertical) is called a current
Pressure is caused by the characteristics
of the air
Warmer Air
X
X
X
X
X
X
X
X
X
X
X
X
Molecules move
faster and are
farther apart.
Less Dense
Cooler Air
More Dense
X X X X X X X X X X
X X X X X X X X X X
X X X X X X X X X
Molecules are
close together
and move
slowly.
Warm Air Rises Cool Air Sinks
Warm Air Rising
Warm Air Rising
Cool Air Sinking
Convection Currents
Cool Air Sinking
Cool Air Sinking
Warm Air
Rising
High Pressure
Ok,
High Pressure is
1. Dense (heavy)
2. Cool
3. Creates Clear Skies
Low Pressure
Ok,
Low Pressure is
1. Less Dense (heavy)
2. Warmer
3. Brings Lousy
Weather
High Pressure
Low Pressure
=
=
Happy Weather
Lousy Weather
HL
Correctly draw the direction of wind flow
on your paper
Winds Blow from
HIGH to LOW
low
pressure
warm or cold air
air rising or sinking
clouds or no clouds
clockwise or
counterclockwise wind
direction
winds toward or
away from the center
high
pressure
In a high pressure area,
air will (rise, sink)
because the air is
(less, more) dense.
This is because the air is
(cold, warm)
and (rises, sinks).
Therefore, clouds CANNOT form.
In a low pressure area,
air will (rise, sink)
because the air is
(less, more) dense.
This is because the air is
(cold, warm)
and (rises, sinks).
Therefore, clouds are
LIKELY to form.
There Are Two Kinds of Winds:
Global and Local
• Global Winds are Winds
that blow over long
distances around the Earth.
• Local Winds are winds that
blow a short distance.
Global Winds
Why Do Different Parts of the Earth
Have Different Temperatures?
North Pole
Equator
South Pole
Thus, radiation is more intense near the equator compared to the poles.
For this reason, it’s warmer near the equator than at the poles.
Global Thermal Temperatures
Air Rises at the Equator
• Air at the Equator is
warm.
• Warm air rises.
• The Equator is a Low
Pressure area.
What Happens to Rising Air at the
Equator?
• At the Equator, air
rises;
• As the air moves
upward, it cools,
• The air begins to turn
to move downward.
• Cold air sinks at the 30o
zone.
Winds blow
from
High Pressure
to
Low Pressure
Let’s Label
High Pressure 90°N
Low Pressure 60 °N
High Pressure 30°N
Low Pressure 0°
High Pressure 30°S
Low Pressure 60°S
High Pressure 90°S
Names of Winds
• IMPORTANT: Winds are named
from the direction they come.
• North winds comes from the north;
south winds come from the south.
• Southeast winds come from the
southeast and blow northwest;
• Northeast winds come from the
northeast and blow to the
southwest.
Let’s Label Easterlies
Polar Easterlies
Trade Winds
Trade Winds
Polar Easterlies
Trade Winds
• The TRADE WINDS are the winds
blowing towards the equator.
• These winds are Easterlies,
blowing from the east.
– South of the equator, the winds
blow from the southeast
– North of the equator, the winds
blow from the northeast.
• They were named because
traders from Europe sailed in
these zones on their way to the
new world.
Let’s Label Westerlies
Prevailing Westerlies
Prevailing Westerlies
Inman is Located in the Westerly
Wind Belt
Why Don’t The Winds Blow in
Straight Lines?
• Cold air from both
the South Pole and
North Pole blows
towards the 60o zone
• But the air doesn’t
flow in a straight line
Coriolis Effect
• Since the earth rotates,
winds do not blow
directly from north to
south or south to north.
• Winds curve
• They curve because the
earth rotates or spins
on its axis.
• The Coriolis Effect is
the curving of winds
due to the earth’s
rotation.
The ball is going
straight, but it
looks like it is
curving.
Global Wind Animation
http://www.geo.hunter.cuny.edu/
~tbw/wc.notes/7.circ.atm/animati
ons/GlobalWind.html
Christopher Columbus
• Columbus used
both the Easterlies
and Westerlies to
go to and from
Spain.
Columbus’s Route to and back
To the New World from Spain, Columbus sailed in the Trade Wind Zone.
From the New World and back to Spain, Columbus sailed in the Westerlies zone.
Zones of NO WIND
Doldrums
At the equator, which
is 0o latitude, there is
a windless zone called
the Doldrums.
Horse Latitudes
At 30o N and 30o S,
there is a windless
zone called the
Horse Latitudes.
Horse
Latitudes
And
The
Doldrums
Doldrums
• Since the Trade Winds blow from both the
North and South, a calm zone occurs.
• This zone is called the “DOLDRUMS.”
• In this zone, there are no winds. Ships
often got stalled for long periods because
they needed wind to blow their sails.
Horse Latitudes
The Horse Latitudes are zones
of calm winds at the 30o
Latitude Lines.
The term horse latitudes
originates from the days when
Spanish sailing vessels
transported horses to the West
Indies. Since there was no
wind, the sail ships that
entered this zone, would get
stuck for weeks.
Since water and food shortages
occurred, the crews found it
necessary to throw their
horses overboard.
o
30 North and South Latitude
This is an area of high pressure. Sinking air means no clouds or
rain.
Air from the Equator and from
the 60o Latitudes cool and
Along this latitude, (between
descend at the 30o Latitude.
15o to 35o) many of the
major deserts are found
Local Winds
• Winds that blow short
distances and in any
direction (depending on
pressure)
• Remember, winds always
blow from areas of high
pressure to low pressure.
EXIT PASS
• WINDS BLOW FROM AREAS OF ______TO
AREAS OF ______.
• DURING THE DAY WHICH HEATS FASTER?
LAND OR WATER
• DURING THE NIGHT WHICH COOLS DOWN
THE FASTEST? LAND OR WATER