1) Lunar day is one complete orbit of the moon around the earth.
The long lunar day id 24 hours 50 minutes.2) Because, the Earth
rotates to its own axis and revolves to the sun. And the moon also
revolves to the Earth. These rotations and revolutions make times
of the tidal events are constantly changing.3) Solar month is
longer than lunar month. Lunar month is 29 days or more than 30
days.4) Diurnal tide cycle experiences one high and one low tide
every lunar day.While, Semi diurnal experiences two high and two
low tides of approximately equal size every lunar day.5) Neap tides
is lower tide ranges occur when the sun and moon are approximately
90 apart, it happens when the moon is in either its first or its
last quarter. While, spring tide is highest tide ranges occur when
the sun , the earth and moon are in a particular line, it happens
when every new and full moon.6) The interval between neap tide and
spring tide is seven days.7) Various charting datums:Highest actual
tide:
Mean high water spring: The highest level that spring tides
reach on the average over a period time.
Mean higher high water: Theaverageheight ofthehigher
highwatersovera 19-year period. thehigher high waterheightsare
included intheaveragewherethetypeoftideisdiurnal.
Mean high water:Theaverageheight ofthehighwatersovera 19-year
period.All high waterheightsareincluded intheaveragewherethetypeof
tide is eithersemidiurnalormixed.
Mean high water (neaps):The average height of thehigh
watersoccurring at the time ofneap tide.
Mean sea level:Theaverageheight
ofthesurfaceoftheseaforallstagesofthetideovera 19-year period,
usuallydeterminedfrom hourlyheightreadings. It
isalsotheaveragewaterlevelthatwouldexistin theabsenceoftides.
Mean low water (neaps):The average height oflow watersoccurring
at the time of theneap tides.
Mean low water:Theaverageheight ofthelowwatersovera 19-year
period.Alllowwaterheightsareincluded intheaveragewherethetypeof
tide is eithersemidiurnalormixed.
Mean lower low water:Theaverageheight ofthelowerlowwatersovera
19-year period. Lowerlowwaterheightsareincluded
intheaveragewherethetypeoftideis diurnal.
Mean low water spring:Theaverageheight
oflowwatersoccurringatthetime ofthespringtides.
Lowest astronomical tide:The lowest levels which can be
predicted to occur under average metereological conditions.
