Transcript WIND

Chapter 2, Section 3
What is wind?
The horizontal movement of air
from an area of HIGH pressure to
an area of LOW pressure
What causes wind?
All winds are caused by the
differences in air pressure
How do fluids move?
From areas of
HIGH pressure
to areas of
LOW pressure.
What causes differences in
air pressure?
Differences in air pressure are
caused by unequal heating of the
atmosphere. (Difference
temperatures of the air)
How is wind direction measured?
 Wind is measured
with a wind vane.
The wind vane
points in the
direction the wind
comes from. Winds
are also named from
the direction they
come from.
How is wind speed
measured?
Wind speed is measured with an
anemometer.
What is the wind-chill
factor, and how does it
affect us?
The increased cooling that winds can
cause.
It is what the air “feels like,” not the
actual temperature. (Cool air moves
across your much warmer skin)
What are local winds?
Local winds are winds that blow
over short distances.
They are caused by unequal
heating of Earth’s surfaces within a
small area. This causes differences
in air temperature.
What is a sea-breeze and
why does it occur?
 A sea-breeze is a light wind that comes
from the sea or ocean.
 It usually occurs during the day because
the sand heats up more than the water
creating a convection current.
What is a land-breeze and
why does it occur?
 A land breeze is a light wind that comes
from the land.
 It usually occurs during the night because
the sand cools down more than the water
creating a convection current.
What is a monsoon?
A monsoon is a
land or a sea breeze
over a large region
that changes
directions with the
seasons.
Explain summertime
monsoons.
During the summer, the land is
warmer, air over the land rises,
cooler air from over the water
(carrying water vapor) moves in to
replace the rising air. The water
vapor creates long periods of heavy
rain.
Explain wintertime
monsoons.
During the winter, the water is
warmer, air over the water rises,
cooler air from over the land moves
in to replace the rising air. This
creates very dry conditions.
What are global winds?
Global winds are
winds that are
steadily blown
over huge
distances.
What causes global winds?
 Global winds are caused by global
convection currents (caused by unequal
heating) and the Coriolis Effect.
 Warm air rising near the equator and cold
air sinking near the poles.
 The cold air replaces the warm air
producing huge global convection currents
Where do global
convection currents RISE?
Global convection currents rise
near the equator because the air is
warmest.
Where do global convection
currents SINK?
Global convection currents sink
near the poles because the air is
coolest.
What is the Coriollis effect?
The Coriollis effect is the way
that the Earth’s rotation causes
the winds to curve.
What are the DOLDRUMS
and where are they found?
An area of calm air near the equator
where warm air is rising causing
very little wind.
What are the HORSE LATITUDES
and where are they found?
An area of calm air near 30° North
and 30° South where cool air is
sinking causing very little wind.
What are the TRADE WINDS
and where are they found?
Winds that blow from
about 30° North and 30°
South towards the
equator and turn
towards the west
Also known as the
Prevailing Easterlies
What are the PREVAILING
WESTERLIES and where are they
found?
Winds that blow
from about 30° North
and 30° South
towards 60° North
and 60° South and
turn towards the east
*These are the winds that affect our weather most.*
What are the POLAR
EASTERLIES and where are
they found?
Winds that blow
from about 60°
North and 60°
South towards the
poles and turn
towards the west
What are the POLAR FRONTS
and where are they found?
An area of calm air near 60° North
and 60° South where warm air is
rising causing very little wind.
What are Jet Streams?
Jet streams are bands of high speed
winds that are about 10 km above
the Earth’s surface.