How to calculate the time of high tide and low tide

The fluctuation of sea water is a geographical phenomenon influenced by the gravity of the moon, so there are rules to follow, and it comes back every 15 days. The climax of the next day was 0.8 hours (48 minutes) later than that of the first day. The daily high tide time can be calculated according to the lunar calendar date. The specific calculation method is as follows:

Method one

1, lunar calendar date is less than 15:

High tide time = lunar calendar date ×0.8

Low tide time = Lunar date ×0.8-6

2, the lunar calendar date is greater than fifteen:

High tide time = (lunar date-15) × 0.8;

Low tide time = (lunar date-15)×0.8-6.

The calculated time is 12 hour.

Method 2

1, the climax time of the day:

Calculation method of the first half of the month: (lunar date-1)×0.8+5.7 = high tide time.

Calculation method of the second half of the month: (Lunar date-16)×0.8+5.7 = high tide time.

2, tomorrow's high tide time calculation method:

Today's high tide time +48 minutes = tomorrow's high tide time.

There are two high tides and two low tides every day. Through long-term practice and observation, it is found that the high lakes and great lakes often appear before and after the mid-day of the moon (that is, after the local time). The low tide time is before and after the moon rises and sets, and the high (low) tide time every day is about 48 minutes later, that is, 48 minutes (0.8 hours) later every day. The two big tides every month are near the first and fifteenth day of the lunar calendar, and the two small tides are near the seventh and eighth, twenty-second and twenty-third day of the lunar calendar. However, in practice, the formation time of high tide and low tide is not exactly the above time, because the shape of the earth is very complicated, so the maximum tide and minimum tide appear in various places a few days later than in theory. For example, the fluctuation of the third and eighteenth tides in the coastal area of Shandong Peninsula is the largest, while the fluctuation before and after the tenth, twenty-second and twenty-fifth tides is the smallest.