How to calculate the tide of the sea, how to calculate the time of the ebb and flow of the seawater

Formula: When the tide rises and begins to recede (the most water).

Lunar days (minus 15 in the second half of the month).

When the tide is low and it starts to rise (when the water is at its least).

When the tide rises and begins to recede, -6 hours.

Take the seventh day of the lunar calendar as an example:

When the tide rises and begins to recede.

7 Note: Since it is an hour and 60 minutes, the 60 tide will start to recede at 5:36 a.m.).

When the tide is out and it starts to rise.

5:36 a.m. - 6 hours = 11:36 a.m.

Take Yin Li Seventeen as an example:

When the tide rises and begins to recede.

17-15) :36.

Since the sea rises and falls twice a day, the time is 12 hours. I have been using the above methods, and the simplicity lies in the direct daily multiplication. Of course, it can't be quite accurate, but it's not far off, and it's enough for us to use for fishing.

Of course, I didn't create this method myself, I also learned it. However, after using it, it is consistent with the calculation method of local fishermen, so I recommend it here.

Due to the action of the tidal force of the sun and the moon, the periodic movements and changes in the earth's lithosphere, hydrosphere and atmosphere are collectively called tides. As a complete tidal science, the research object should take the earth tide, ocean tide and air tide as a unified whole, but because the phenomenon of ocean tide is very obvious and closely related to people's life, economic activities, transportation, etc., it is customary to understand the word tide in a narrow sense as ocean tide. The elastic-plastic deformation of the solid earth caused by the gravitational force of the sun and the moon is called the solid tide, referred to as the solid tide or ground tide.

Tide. The periodic rise, fall, advance and retreat of the sea surface caused by the gravitational force of the sun and the moon are called ocean tides, referred to as ocean tides.

The periodic changes (such as hours) caused by the gravitational force of various elements of the atmosphere (such as the pressure field, the atmospheric wind field, the earth's magnetic field, etc.) are called atmospheric tides, referred to as air tides.

Among them, atmospheric tides caused by the sun are called solar tides, and those caused by the moon are called lunar tides.

The ebb and flow of seawater (tide) refers to the periodic rise, fall, advance and retreat of the sea surface caused by the tidal force of the sun and the moon. Among them, the atmospheric tide caused by the sun is called solar tide, and the solar tide caused by the moon is called the solar tide. Because the Moon is closer to the Earth than the Sun, the ratio of the gravitational force of the Moon to the Sun is 11:

5. For the ocean, the solar tide is more significant than the solar tide.

In ancient times, the tides during the day were called "tides", and the tides at night were called "tides", which were collectively called "tides". On the first day of the lunar month, that is, at the time of the new year, the sun and the moon are on the side of the earth, so there is the greatest gravitational force, so it will cause a "big tide", near the fifteenth or sixteenth day of the lunar month, the sun and the moon are on both sides of the earth, and the gravitational force of the sun and the moon will also cause a "big tide"; When the moon phase is the first and second wind, that is, the eighth and twenty-third hours of the lunar calendar, the gravitational force of the sun and the gravitational force of the moon cancel out part of each other, so there is a "small tide", so there is a saying in the agricultural proverb that "the tide rises on the fifteenth day of the first month, and the beach is seen everywhere on the eighth and twenty-third days of the lunar calendar". In addition, there is also a high tide on the first day, because the moon moves eastward on the celestial sphere by more than 13 degrees every day, which is about 50 minutes in total, that is, the time of the moon on the middle of the sky (1 lunar day = 24:50) is delayed by about 50 minutes, (the tide also occurs in the lower midheaven and there are generally two tides a day), so the time of the high tide every day is also delayed by about 50 minutes.

I am from Shanhaiguan and want to pay attention to the tide every day.

Anyone who has ever been to the beach knows that the sea has both high and low tides. At high tide, the sea is **, the waves are rolling, and the scenery is spectacular; At low tide, the water quietly recedes, revealing a beach. Rising and low tides generally occur twice a day.

The rise and fall of the sea water occurs during the day and is called the tide at night, so it is also called the tide. In the ancient books of our country, it is said that "the water of the sea is the tide in the morning and the tide in the evening". There is a period of time between high tide and low tide when the water level does not rise or fall, which is called flat tide.

How is it formed? Let's start with the flat tide, which is the general state of the sea. We all know that when the earth rotates, it produces a centrifugal force that throws outward.

For example, it's like spinning an open umbrella, and the water droplets on the umbrella are about to be thrown out, so the sea will fluctuate in normal times. Let's talk about the tides. We also know that not only does the rotation of the earth affect the unrest of the sea, but our earth is also affected by the gravitational pull of the moon and the sun.

Think about it, when the earth turns to follow the gravitational direction of the sun or moon, is the sea water facing the sun or moon attracted by a gravitational force, and when it is attracted, there is a force that flows outward and wants to rise up and rush out into the air? But, after all, the gravitational pull of the moon is not strong enough, and the sun is too far away, so they can only lift the sea, let the sea rise, and cannot let it go into space... When the earth turns to offset the gravitational direction of the sun and the moon, it naturally returns to its original state.

Got it? Therefore, the tide usually occurs twice a day. In one day, except for the north and south poles and individual regions, the tides rise and fall twice in each day, each time for 12 hours and 25 minutes, twice a day, a total of 24 hours and 50 minutes, so the time of tide rise and fall is delayed by 50 minutes every day.

It is precisely because of such fluctuations that the seawater can be temporarily replenished by the water that does not rise in other places when the tide rises in one place, thus forming a tidal current and facilitating the exchange of the seawater environment. Resources.

Answer: To understand the tide time, we must first understand the origin of the tide data table, the numbers on the left and right of the tide table are the daily tide height, and the top and bottom are the time (represented by 0-0). The left and right represent the sea level altitude of the region (the conversion unit is meters), which is what we call the altitude, the rise and fall of the tide is measured according to this data, when the tide is high, it means that the tide has been **, the height of the tide is adjusted according to the gravitational force of the earth and the moon, he is divided into 15 days for a high tide rise and fall tide cycle, of which the first and fifteenth day of the new month is the highest period of the tide, that is, the so-called high tide, the duration is 3-4 days, The rest of the time is a light tide period, which is related to the full moon of the moon. If you want to catch fish in the sea, you must first know the time and changes of the tide.

The following is an example of the data of the tide table on May 18, first of all, we start to calculate from 12 o'clock in the evening on the 17th to 12 o'clock in the evening on the 18th, and the time is for 24 hours.

1. The first time period should be: from 3 o'clock in the morning to 6 o'clock in the morning on the 18th, this is the menarche period, which is the peak period of foraging for fish in the morning, that is, the first breakfast time after the fish has passed a night.

From 6 a.m. to 11 a.m., the peak tide is at this time. At this time, the fish because the tide is basically not flowing at a high level, and the fish is also in the rest time, at this time it is basically difficult to catch the big fish, because the big fish will leave the reef area in the case of the tide flow is not smooth, and the small fish will visit the place occupied by the big fish in large groups, at this time you should consider the appropriate rest and nourish the spirit. Fishing.

3, 12 o'clock - 15 o'clock for the low tide period, this period of time due to the first low tide, the flow of water increases, after a short rest of the big fish in the tide under the impetus of the water has returned to the place occupied by the small fish, chasing the small fish, this time period due to the big fish and small fish mixed together, in the use of bait to use hard bait (such as with sugar to drown the hard shrimp meat or live bait, etc.), otherwise the bait is not in the end when the small fish snatch clean and can not reach the big fish hiding place, You don't catch a big fish either.

4. From 6 p.m. to 11 p.m., it is the peak point of the second big fish hunting time of the day, that is, dinner time, this time period is due to the fact that the small fish are already in the rest time after a day of fatigue, basically will not come out to look for time, this is the favorite time of the angler, as long as there is movement at this time, you have to be careful scouting, the fish below is definitely not a little guy.

5. From this, it is not difficult for us to see that the fishing time can be simply divided into two categories:

The Yangtze River Estuary is a moderately strong tidal estuary, which is an irregular semi-diurnal tidal type. Due to the wide entrance gate and the strong wind, the tidal inflow is very large, and the tidal inflow of the two full tides can reach about 6 billion cubic meters.

The north branch of the Yangtze River estuary starts from Chongtou in the west, reaches Lianxing Port in the east, with a total length of about 79km, the narrowest part of Qinglong Port section only, the widest part of Lianxing Port section is 16km, with an area of about 800,000 mu, which belongs to the trumpet-type high tide trough estuary. To the east of Qinglong Port, the river channel is widened, to Daxingang, the river channel shrinks again, below Daxingang, the river channel gradually widens, and there are two deep troughs in the north and south, the north trough is dominated by the rising tide, the south trough is mainly the falling tide, and the sandbar between the two troughs is dense, among which Yonglong Sha was connected to Chongming Island in 1973, and Xinglong Sha has also been reclaimed (see figure). The north branch section is an irregular half-day shallow sea tide, the average high tide duration of Qinglong Port section is hours, the average low tide duration is hours, the average high tide duration of Haikou section is hours, and the average low tide duration is hours.

The maximum tidal range Qinglong Port is, the three ports are, the average tidal range Qinglong Port is, and the three ports are. The average tidal volume per tide is 2.6 billion m3, and the north branch carries the runoff of the Yangtze River, and the average daily freshwater inflow from the Yangtze River is about 100 million m3.

Supplement: Empirical estimation of tides in the Yangtze River section The tidal fluctuations of the Yangtze River section have a certain regularity, and the Shanghai Maritime Safety Bureau compiles and publishes the "Tide Table of Shanghai Port and Hangzhou Bay" every year for the reference of seafarers, but only the tidal time and tide level data of the ports below Jiangyin, these theoretical tide calculation data, have a good reference role for ships to grasp the tide rise and fall and the size of the tide level. In addition, there is also a tidal empirical calculation algorithm for the Yangtze River section, the third and eighteenth days of the lunar calendar are the high tide periods, with Wusongkou as the reference point, and the third day of the first month is 11:

The high tide starts at 00 o'clock, and under normal circumstances, the high tide is 5 hours, the low tide is 7 hours, and then there is a delay of 48 minutes (i.e. hours) every day, and so on. The farther other ports affected by the tide are from Wusongkou, the time of high tide is correspondingly delayed, and the degree of tidal influence is correspondingly reduced. The delay time of the tide is estimated by experience, and there is also a certain rate, that is, it is about 30 kilometers away from Wusongkou and delayed for one hour, according to this calculation, the delay of the high tide in Wusongkou in Wolf Mountain is 5 hours, the port hour is 5 hours, the port hour is 8 hours, the Zhenjiang is 8 hours, Nanjing is 11 hours, and Wuhu is 13 hours.

In order to make it more convenient to check the specific high tide time of each section, you can understand the high tide situation of a certain section and a certain period of time through the following "Wusong-Wuhu High Tide Time Estimation Table".