Why latitude is not enough
Even at similar latitude, elevation, proximity to water, local weather, species, and microclimate can shift biological events. This release treats those as explanatory factors, not as a predictive formula.
Flagship / compare
Variation Comparator
Compare definitions of spring by basis, best use, and boundary. The point is not to crown one “correct” definition; it is to stop one kind of evidence from silently impersonating another.
Why a calendar is still useful
Fixed seasonal groupings make statistical comparisons easier. Their value comes from consistency, not from proving that every organism or place has entered the same state.