The Coriolis Effect
and Weather
Science 10 Day 13
http://www.youtube.com/watch?v=WXuGYSM2D8k
What is the Coriolis Effect?
The Coriolis Effect describes the turning of
wind and water due to the Earth’s rotation.
Coriolis Effect
The Coriolis Effect causes
air and water to:
– turn to the right in the
northern hemisphere
– turn to the left in the
southern hemisphere.
What happens at the Equator?
http://youtu.be/-hbE3rTZLbQ
Coriolis Effect
Why the difference?
– If you were in space, looking down at the north
pole, the Earth would be rotating counter clockwise
BUT
– If you were in space, looking down at the south
pole, the Earth would be rotating clockwise.
The Coriolis effect has a huge influence over
weather patterns!...
Stop & Think!
•If the Earth did not rotate,
and was much smaller, there
would be a large convection
current in each hemisphere.
Coriolis Effect
There are actually 3 smaller
convection currents in each
hemisphere.
What influence does the
Coriolis effect have on these
convection currents?
https://www.youtube.com/wat
ch?v=Ye45DGkqUkE
Section
1.2
Global (Prevailing) Wind Systems
3 major wind systems of
prevailing winds are:
1. Trade Winds
2. Prevailing Westerlies
3. Polar Easterlies
They are caused by:
1. Convection cells
2. Coriolis Effect!
UNIT Chapter 1: Inquiring about Weather
1
Jet Streams
• A jet stream is a narrow band
of fast-moving wind caused
by temperature differences.
• Usually a few kilometers high,
and a few hundred meters
wide.
• Why do you think it’s called
the JET stream?
Section
1.2
Highs and Lows
Air mass
a large portion of air that is
nearly uniform in
temperature and humidity.
On weather maps, you will
always see several high
and low pressure systems
symbolized as 'H' and 'L'.
High pressure system:
form over cold land.
air cools  becomes more dense and settles.
descending air exerts more pressure on the region below.
when the falling air reaches the ground, it moves outward turns to the
right due to the Coriolis affect.
High pressure systems turn clockwise in the Northern Hemisphere.
High pressure systems create clear skies; clouds do not form because
air is dry.
Low pressure system:
• form over very hot land i.e. deserts.
• Hot ground heats air by conduction  hot air rises.
• rising air results in a low pressure zone below it.
• Surrounding air moves in to replace the rising air. As it does, it
turns to the right due to the Coriolis affect.
• Low pressure systems turn counter-clockwise in the Northern
Hemisphere.
• Low pressure systems bring unstable weather, precipitation and
storms.
Ocean Currents Also Affect Weather
Where do cool
ocean currents
originate?
Look at the circular
movement of
currents – in which
direction do they
move in the
hemispheres?
Where do warm
ocean currents
originate?
The Basics
• The Earth is a sphere and rotates on an
axis (counterclockwise when looking down
at the north pole)
• The equator rotates faster than areas
further north or south to “catch up”.
http://techtv.mit.edu/videos/3714-the-coriolis-effect