Like Equinoxes the dates of Equiumbra at a particular location are around the same time each year. Equiumbra occurs when a vertical object casts a shadow exactly equal in length to its height. The dates of Equiumbra are specific to a particular latitude. On the 10th April 2021 at midday this occurred at latitude 52.96˚ when the sun was 7.96˚ above the equator.