Ocean Tides

Weigh a container of some sort, place the water in the container and then subtract the weight of the container from the total weight of the container and water. For example: my glass bowl weighs 1 pound. When I weigh the bowl filled with water, it is 3 pounds. 3 pounds minus the 1 pound makes 2 pounds. The water weighs 2 pounds.

The times of high and low tide shift a little each day, so usually you'll get one high and one low tide in a day.

Occasionally you can get high-low-high or low-high-low in one day, but this is quite rare.

No. Eclipses are simply shadows; they don't really affect anything.

However, we do know that since eclipses only occur at full moons or new moons, an eclipse always coincides with a "spring tide".

because rivers are at high level from the sea as the radius of earth increases the force of attraction also increases. sea level are at the lowest point of land in the earth the force of attraction is less at that place because force of attraction is diractly proportional to the radius of the heavenly bodies.

High tides. The others are called low tides.

No, not at all. Tides are caused by the gravitational pull of the moon and the sun on the earth's waters. The earth rotates once every 24 hours and the earth/moon system rotates roughly once every 27 days. The complex interaction between the two creates a pattern that repeats roughly every 24 hours and 50 minutes. In other words, the whole pattern of high and low tides shifts by a bit under an hour every day.

But there's still more: Within that pattern there oscillations that produce two different high and two different low tides every day, so there's about 6 hours and 12 minutes between any pair of high and low tides.

neap tide

Tides affect fishing because they can provide plenty of fish for fishermen. For example, when the tide is moving, it is more productive and doesn't have slack. When there is less of a slack, then there will be more fishes in the surf.

Isopods are species of crustaceans found in oceans.

The intertidal zone is an area of ocean which is above the water at low tide and underwater at high tide (in other words, the area between tide marks).

About twice a day.

The four main factors that affect tides are the gravitational pull of the moon, the gravitational pull of the sun, the rotation of the Earth, and the shape of the coastline.

It happens in most coastal areas of the Earth (not all) and is due to the differing force of gravity at different distances.

The Earth is a 'rigid' body moving in free-fall in its orbit, with the Sun's gravity acting in effect at its centre. The ocean experiences a greater force where the Sun is overhead (because it's closer), and a lesser force at the opposite point (because it's further away). Where the Sun is overhead the net force is towards the Sun, and at the opposite point it is away from the Sun. So there are two areas of deeper water per 24 hours.

In reality the movement of the oceans is complicated by the presence of land-masses, so the actual movement is very complex. It is also made more complex by the Moon's gravity, but the principle is the same.

If the Earth were a long distance from the Sun there would be a smaller difference between the forces on opposite sides of the Earth and the tidal effect would be less.

So if you know that low tide is at 0800 today you can estimate that it will be at 0850 tomorrow.

The intertidal zone

During a spring tide, the high water mark would be high up on the beach on the flood, and very far out on an ebb tide. During a neap tide, the high water mark is not so high or so low as during a spring tide.

When the moon is going in its orbit, because it is an elipse, it will be closer to the Earth at different times. Therefore, the Moon's gravity will be stronger, or weaker everyday, which makes it take more or less time between the tides.

http://www.pol.ac.uk/home/insight/tideinfo.html Proudman Oceanic Laboratory states that spring tides and neap tides occur twice a month. Interestingly, they occur on the earth between 36 to 48 hours after the full moon and the new moon when the earth, moon and sun are aligned. http://www.waterencyclopedia.com/St-Ts/Tides.html A good illustration of the position of the earth, sun and moon during neap tides and spring tides makes it clear why there are two of each per month. From the Water encyclopedia. http://svs.gsfc.nasa.gov/stories/topex/index.html Shows how the topography of the ocean floor can dissipate energy and causes the tides to be lower than anticipated.

Tides ebb and flow twice a day.

No, the moon does.

Back when the moon still rotated, earth's gravity would have induced a small amount of tidal motion in the lunar regolith, just as the moon induces tides in earth's crustal rock. These tides are not large, just fractions of an inch (millimeters). The tides in free flowing material like water get much higher (measured in feet or a meters).

Today (and for untold eons) the moon has been tidally locked to earth, and rocks back and forth very little during its month long journey around the earth. This rocking motion exerts tidal effects on the lunar surface, but again it is very small.

Tides are periodic rises and falls of large bodies of water. Tides are caused by the gravitational interaction between the Earth and the Moon. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since the Earth is also being pulled toward the moon (and away from the water on the far side). Since the earth is rotating while this is happening, two tides occur each day.

There are generally two high and two low tides during each 24 hour period, so there would "usually" be four changes per day.
There are two low, and two high tides every Lunar day. A lunar day is the time it takes a fixed spot on the earth to rotate from beneath the moon, and to reach the moon again.

sublittoral

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