Why does the severn bore happen only at the equinox?

The Severn Bore is a tidal phenomenon that occurs when the tide from the Atlantic Ocean rushes up the Severn Estuary, creating a large wave. It is most pronounced around the equinoxes due to the alignment of the Earth, sun, and moon, which leads to higher tidal ranges. During these periods, spring tides occur, resulting in more significant tidal fluctuations that enhance the bore's intensity. Factors such as the estuary's shape and geography also contribute to the wave's formation.