Lunitidal interval
Encyclopedia
The lunitidal interval, measures the time lag from the moon passing overhead, to the next high or low tide
. It is also called the high water interval (HWI)/
Tides are known to be mainly caused by the moon's gravity. Theoretically, peak tidal forces at a given location occur when the moon is at the meridian
, but there is usually a delay before high tide that depends largely on the shape of the coastline, and the sea floor, therefore, the lunitidal interval varies from place to place. The lunitidal interval further varies within about +/- 30 minutes according to the lunar phase.
The approximate lunitidal interval can be calculated if the moon-rise, moon-set and high tide times are known for a location. In the northern hemisphere, the moon is at its highest point when it is southernmost in the sky. Lunar data are available from printed tables and online . Tide tables tell the time of the next high water . The difference between these two times is the lunitidal interval. This value can be used to calibrate certain clocks and wristwatches to allow for simple but crude tidal predictions.
Tide
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....
. It is also called the high water interval (HWI)/
Tides are known to be mainly caused by the moon's gravity. Theoretically, peak tidal forces at a given location occur when the moon is at the meridian
Meridian (astronomy)
This article is about the astronomical concept. For other uses of the word, see Meridian.In the sky, a meridian is an imaginary great circle on the celestial sphere. It passes through the north point on the horizon, through the celestial pole, up to the zenith, through the south point on the...
, but there is usually a delay before high tide that depends largely on the shape of the coastline, and the sea floor, therefore, the lunitidal interval varies from place to place. The lunitidal interval further varies within about +/- 30 minutes according to the lunar phase.
The approximate lunitidal interval can be calculated if the moon-rise, moon-set and high tide times are known for a location. In the northern hemisphere, the moon is at its highest point when it is southernmost in the sky. Lunar data are available from printed tables and online . Tide tables tell the time of the next high water . The difference between these two times is the lunitidal interval. This value can be used to calibrate certain clocks and wristwatches to allow for simple but crude tidal predictions.
