It’s that time of the month again where we experience a glorious full moon rising from behind the Tsitsikamma Mountains and witness the sea pushing its water further and higher up the beach as the moon affects the tides.
A full moon is a lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. More precisely, a full moon occurs when the geocentric apparent longitudes of the Sun and Moon differ by 180 degrees; the Moon is then in opposition with the Sun. As seen from Earth, the hemisphere of the Moon that is facing the Earth (the near side) is almost fully illuminated by the Sun and appears round. Only during a full moon is the opposite hemisphere of the Moon, which is not visible from Earth (the far side), completely dark.
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth. The difference in height between high and low waters over about half a day varies in a two-week cycle. Approximately twice a month, around new moon and full moon when the Sun, Moon and Earth form a line the tidal force due to the sun reinforces that due to the Moon. The tide’s range is then at its maximum: this is called the spring tide. It is not named after the season but, like that word, derives from the meaning “jump, burst forth, rise”, as in a natural spring.
Spring tides result in high waters that are higher than average, low waters that are lower than average, ‘slack water’ time that is shorter than average and stronger tidal currents than average. Neaps result in less extreme tidal conditions. There is about a seven-day interval between springs and neaps.