Coriolis Force for North-South Motions!
Derived from conservation of
total angular momentum along!
Earthʼs axis of rotation!
A! B!
Imagine you and an air parcel
are at rest on Earth. You nudge
the air parcel due north from
point A (along the longitude
intersecting A). You continue
looking north as you rotate. Horizontal Arrows represent motion
Sometime later you arrive at B. of objects fixed to surface!
Now due north is along the
Arrows 1 and 2 are not fixed to the
longitude intersecting B. The
surface!
parcel is at the yellow arrow
head, to the right of the Arrow 1 shows the deflection to the
longitude, moved by the right of the upper horizontal arrow!
Coriolis force.!
Arrow 2 shows the deflection to the
left of the middle horizontal arrow!
Coriolis Force for East-West Motions!
Results from the change in centrifugal
force caused by motion. The
centrifugal force of objects at rest on
earths is balanced by the departure of
true gravity g* from the local apparent
gravity g. !
If you nudge a formerly resting parcel
to the east, the motion adds to the The red arrow is the displacement
rotation and causes the centrifugal from the “extra” centrifugal force for
force to exceed what gravity can an object initially moving east (out
balance. This “extra” centrifugal force of page) w.r.t. Earth. The pink
is the Coriolis Force.! arrows are its local Cartesian
coordinate components. !
(lower arrows are for initial
westward motion)!
Facts about the Coriolis Effect:!
•Displaces winds to the right in the NH (left
in the SH)!
•Only acts when an object is in motion on a
rotating body!
•It is zero on the equator!
•Doesnʼt have a significant effect on water
in your sink!
•Does affect midlatitude storms and
airplane travel!
