# Beta spiral

From AMS Glossary

## beta spiral

In oceanography, the turning of the current vector that arises from stratified geostrophic flow when density is conserved following a parcel (as is approximately the case in the oceanic thermocline).

If θ is the angle of the current,

*U*is its magnitude,*f*is the Coriolis parameter,*g*is the gravitational acceleration, and*w*is the vertical velocity, then ∂θ/∂*z*= -(*gw*/*f'***U**^{2})(∂ρ/∂*z*), so that moving upward in the water column, currents will spiral clockwise in upwelling zones, and counterclockwise in downwelling zones.