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13.6 Wind and
OceanCurrents
Science 10
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A Little Background
Atmospheric Pressure is theforce of the air pressing downon the earths surfaceAtmospheric pressure is
measured using a barometer.
Since air molecules are so spreadout lots of empt! space"# wedont feel the pressure that the!e$ert
%ifferences in air pressure helpcause winds and affect airmasses. &he! are also factorsin the formation of storms suchas thunderstorms# tornadoes
and hurricanes.
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'hat is 'ind(
'ind is a mo)ement of air in theatmosphere
*ow 'ind %e)elops
+aused b! a difference in air pressure
due to une,ual heating of theatmosphere.
-uestion 'here on the planet does thesurface get heated more than otherareas(...
At the /arths surface# wind alwa!sblows from areas of high pressure toareas of low pressure
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*ow are 'inds +reated(
'inds are created b!.
0. *eating the air# decreases pressure warm airrises creating a low pressure"
1
2. +ool air rushes into replace the warm air
cooler dense air# produces high pressure"1
3. As air goes from high to low pressure windsform
&his is a +456/+&745 st!le +on)ection+urrent %emo &ime88
http99www.!outube.com9watch():;$''ow
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+lassif!ing 'inds
I. Localized
= affect onl! small areas
Tpes of Local Winds
Sea Bree>es= from sea to land Land Bree>es= from land to sea
II. !re"ailing winds
= affect large areas#= t!pes to follow after we look at
what causes pre)ailing winds
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+auses of Pre)ailing
'inds %ue to a combination of
con)ection currents and
coriolis effect
air at the e,uator is warmed
and rises# forming a
con)ection current called the
e,uatorial con)ection current
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&he +oriolis /ffect
/arths rotation causes an!thingthat mo)es L45? %7S&A5+/S#
such as pre)ailing winds# to
APP/A@ to change directions.
&he apparent change in direction
of a mo)ing obect in a rotating
s!stem is called the +4@74L7S
//+&.%emo 6ideo
http99www.!outube.com9watch():mcPsC4d-4DE
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+oriolis cont
/)ident on the earth because as
/arth rotates eastward# an obect
tra)elling from north to south will
appear to mo)e to the right 7n the southern hemisphere
obects mo)ing from the pole
appear to mo)e to the left
&he +oriolis effect is more
predominant closer to the poles
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Pre)ailing 'ind
&erms !olar easterlies occur between
FG degrees latitude and the polesand mo)es east to west
#id$latitude westerlies occurs
between 3G degrees and FG degreeslatitude and mo)e from west to east %ortheast trade winds occur ust
north of the e,uator and mo)e eastto west
Southeast trade winds occur ustsouth of the e,uator and mo)e eastto west
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/ffects of Pre)ailing
'inds *elp distribute large amounts
of solar energ! from the
e,uator to the colder parts of
the world.
Also carr! moisture# causing
a )ariet! of precipitation
snow# rain# etc"
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'ind terms cont
?usts occur because of a
rapid air pressure change
and mo)e in no fi$ed
direction
S,ualls gusts accompanied
b! rain
'ind speed indicator
ane&o&eterane&o&eter9weather )ane
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Sooooooo %o !outhink the Coriolis 'ffect
and Windeffect how
water mo)es in the
ocean(
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4cean +urrents
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4cean +urrents
Hass mo)ement orflow of ocean water
@i)er within theocean
&wo t!pesSurfaceSurfaceand (eep(eep
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Surface +urrent
*ori>ontal# stream=likemo)ements of water thatoccur at or near the
surface of the ocean +an reach depths of
se)eral hundred meters
Surface +urrent Animation
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@ed current : warm current
Blue current : cold current
Surface currents flow in a circular pattern 5orthern *emisphere flows clockwise
Southern *emisphere flows counter=clockwise
Poles flow in opposite direction
5otice that the warm currents flow from the e,uator
S f
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Surface
+urrents +ontrolled b! three factors
!re"ailing winds: +ause
surface currents to flow inthe direction the wind isblowing top IGG m"
Coriolis 'ffect
Continental (eflections:shape of the land it flowsup against
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%eep +urrents
Stream like mo)ement ofocean water far below thesurface. &*7S 7S 'AD %4'5&*/@/8
+aused b! changes in densit! &his change in densit! is the
result of changingtemperature and salinit!
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+auses# broken down Change in te&perature
%ecreasing the temperature its colder" ofwater increases densit! water sinks"
Change in salinit 7ncreasing the salinit! of water increases
densit! again# making water sink" Salinit! increases because when water at the
poles free>es# the salt doesnt free>e so itsleft behind and sinks to the ocean floor and isreplaced b! new water hence the current"
Both &/HP/@A&E@/ A5% SAL757&D causes
warmer less dense water from the e,uatormo)es to replace it water will alwa!s want tobe le)el and that is wh! the water that lea)esgets replaced"
&he Pic on the ne$t page does a good ob
e$plaining this phenomena
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