One can find both counterclockwise and clockwise flowing drains
in both hemispheres. Some people would like you to believe that
the Coriolis force affects the flow of water down the drain in
sinks, bathtubs, or toilet bowls. Don’t believe them! The
Coriolis force is simply too weak to affect such small bodies of
In his work “Sur les equations du movements relative des
systems des corps” (1835) the French engineer Gaspard Gustav
de Coriolis (1792-1843) first described this force. The Coriolis
force is caused by the earth’s rotation. It responsible for
air being pulled to the right (counterclockwise) in the Northern
Hemisphere and to the left (clockwise) in the Southern Hemisphere.
The Coriolis Effect is the observed curved path of moving objects relative to the surface of the Earth. Hurricanes are good visual examples. Hurricane air flow (winds) moves counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere. This is due to the rotation of the Earth. The Coriolis force assists in setting the circulation of a hurricane into motion by producing a rightward (clockwise) deflection that sets up a cyclonic (counterclockwise) circulation around the hurricane low pressure. (For a more in depth discussion on hurricanes see NASA’s Hurricanes: Greatest Storm on Earth.)
What happens at the equator? The Coriolis force is too weak to
operate on the moving air at the equator. This means that weather
phenomena such as hurricanes are not observed at the equator, although
they have been observed at 5 degrees above the equator. In fact,
the Coriolis force pulls hurricanes away from the equator.
For a more detailed explanation of the Coriolis Force see Science
around the Coriolis effect" - This paper provides
a scientific explanation of the Coriolis effect complete
with diagrams and examples. It was written by David
J. Van Domelen, of the Ohio State University Department
of Physics, Physics Education Research Group. Also see "A (Hopefully) Simple Explanation of the Coriolis Force."
Wind Industry Association - The Coriolis Force
This Web site provides animated models of how the Coriolis
Coriolis - The author of this Web site sets the
record straight about the Coriolis Force. Presented
are numerous cases where incorrect information was
provided by reliable sources. Also included are Frequently
- Coriolis Force -
Included in this Web site, from the University of Illinois
at Urbana-Champaign, is an explanation of the Coriolis
Force and a video demonstrating the Force.
John C. Exposing the bathtub Coriolis myth. The Physics
Teacher, V. 32, Feb. 1994, v32: p107.
Henry M. and Dennis W. Moore. An introduction to
the Coriolis Forces. New York, Columbia University
Press, c.1989. 297 p.
of Physics. Detroit, Gale Group, 2001: 135-136.
more print resources...
Search on "Coriolis," "hurricanes," and general
books on meteorology and physics
in the Library of Congress Online
on to tree during hurricane. From the Prints and Photographs
Division of the Library of Congress.
Super Typhoon Imbudo - China on July 23, 2003 From NASA 's Earth
From Environmental Health Perspectives
Volume 111, Number 5, May 2003