  A fraction of solar active regions are observed to have current helicity of a
sign that contradicts the polarity law for magnetic helicity; this law
corresponds to the well-known Hale polarity law for sunspots. A significant
excess of active regions with the "wrong" sign of helicity is seen to occur
just at the beginning of the cycle. We compare these observations with
predictions from a dynamo model based on principles of helicity conservation,
discussed by Zhang et al. (2006). This model seems capable of explaining only a
fraction of the regions with the wrong sign of the helicity. We attribute the
remaining excess to additional current helicity production from the twisting of
rising magnetic flux tubes, as suggested by Choudhuri et al. (2004). We
estimate the relative contributions of this effect and that connected with the
model based on magnetic helicity conservation.
