In-class Exploration 2: Coriolis Acceleration,
Scales of Circulation and Wind

Newton's Second Law of Motion (the Equation of Motion) can be restated in the folloiwng manner: an object moving at a certain velocity, will continue to move in a straight line at tht speed, forever, unless acted upon by another force or combination of forces. We have already observed one of these forces, the pressure gradient force. If the pressure gradient force were the only force that affected air motion, then all air parcels would move at right angles to isobars (or height contours....the "equivalent" of isobars if the vertical coordinate is pressure and not height).

We have already observed on the sealevel weather map that although air does indeed drift across isobars from high to low pressure, it does not move at right angles to the isobars, but in a spiraling motion relative to pressure centers. In addition, we now note that the air motion in the "free atmosphere" (the portion of the atmosphere unaffected by friction) tends to be parallel to the isobars or height contours. How can this be?According to Newton's Second Law of Motion, the motion of air relative to the isobars on a rotating earth, must be accounted for by forces. Clearly there must be an additional "force." This additional force is that due to Coriolis.

Demonstration 1

Demonstration 2

Coriolis Acceleration

Length of Deflection Due to Coriolis

Applications:

• Cyclone and Anticyclones: Winds (Rules) and Graphic
• Subtropical Highs
• Ocean Current Gyres
• Upwelling: Illustration 1 and Illustration 2