University of Illinois

> online guides
  educational cd-rom
  current weather
  about ww2010

Online Guides
> meteorology
  remote sensing
  reading maps
  projects, activities

  air masses, fronts
  clouds, precipitation
  el nino
> forces, winds
  hydrologic cycle
  light, optics
  midlatitude cyclones
  severe storms
  weather forecasting

Forces, Winds
  pressure gradient
> coriolis force
  geostrophic wind
  gradient wind
  boundary layer wind
  sea breezes
  land breezes

User Interface
> text

NOTE: We've guessed that you're not using a client that supports colored tables and have tried to compensate. Low graphics mode looks much better on clients that do... we recommend switching to Netscape 3.0 or Microsoft Internet Explorer.
Coriolis Force
an artifact of the earth's rotation

Once air has been set in motion by the pressure gradient force, it undergoes an apparent deflection from its path, as seen by an observer on the earth. This apparent deflection is called the "Coriolis force" and is a result of the earth's rotation.

As air moves from high to low pressure in the northern hemisphere, it is deflected to the right by the Coriolis force. In the southern hemisphere, air moving from high to low pressure is deflected to the left by the Coriolis force.

The amount of deflection the air makes is directly related to both the speed at which the air is moving and its latitude. Therefore, slowly blowing winds will be deflected only a small amount, while stronger winds will be deflected more. Likewise, winds blowing closer to the poles will be deflected more than winds at the same speed closer to the equator. The Coriolis force is zero right at the equator.

This process is further demonstrated by the movie below.

QuickTime (2.0M)
MPEG (0.9M)
Real Life Example:
This movie of a ball rolling across the surface of a rotating merry-go-round is a helpful demonstration of the Coriolis force.

pressure gradient
Terms for using data resources. CD-ROM available.
Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.

geostrophic wind