Are there always two high tides a day?
No. Although most places in Britain experience approximately two tides a day (semi-diurnal) there are some places which experience what is known as a double-high water (e.g. Southampton) or double-low water (e.g. Portland). This is caused by the shape of the coastline and the bathymetry (sea depth). The diagrams below show a typical tidal curve for three places round the UK coast. Liverpool Tides Lowestoft Tides Portland Tides In some parts of the world there is only one high and one low water each day (diurnal) – for example in Karumba, Australia. In other places, it varies between semi-diurnal and diurnal as in Musay-id in the Arabian Gulf.
No. Although most places in Britain experience approximately two tides a day (semi-diurnal) there are some places which experience what is known as a double-high water (e.g. Southampton) or double-low water (e.g. Portland). This is caused by the shape of the coastline and the bathymetry (sea depth). The diagrams below show a typical tidal curve for three places round the UK coast. In some parts of the world there is only one high and one low water each day (diurnal) – for example in Karumba, Australia. In other places, it varies between semi-diurnal and diurnal as in Musay-id in the Arabian Gulf.
