http://www.tide-forecast.com/locations/Clinton-Harbor-Connecticut/tides/latest 

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.

Tide tables can be used for any given locale to find the predicted times and amplitude (or "tidal range"). The predictions are influenced by many factors including the alignment of the Sun and Moon, the phase and amplitude of the tide (pattern of tides in the deep ocean), the amphidromic systems of the oceans, and the shape of the coastline and near-shore bathymetry. They are however only predictions, the actual time and height of the tide is affected by wind and atmospheric pressure. Many shorelines experience semi-diurnal tides—two nearly equal high and low tides each day. Other locations have a diurnal tide—one high and low tide each day. A "mixed tide"—two uneven magnitude tides a day—is a third regular category.

Tides vary on timescales ranging from hours to years due to a number of factors, which determine the lunitidal interval. To make accurate records, tide gauges at fixed stations measure water level over time. Gauges ignore variations caused by waves with periods shorter than minutes. These data are compared to the reference (or datum) level usually called mean sea level .

While tides are usually the largest source of short-term sea-level fluctuations, sea levels are also subject to forces such as wind and barometric pressure changes, resulting in storm surges, especially in shallow seas and near coasts.

Tidal phenomena are not limited to the oceans, but can occur in other systems whenever a gravitational field that varies in time and space is present. For example, the shape of the solid part of the Earth is affected slightly by Earth tide, though this is not as easily seen as the water tidal movements.

Tide changes proceed via the following stages:

• Sea level rises over several hours, covering the intertidal zone; flood tide.

• The water rises to its highest level, reaching high tide.

• Sea level falls over several hours, revealing the intertidal zone; ebb tide.

• The water stops falling, reaching low tide.

Oscillating currents produced by tides are known as tidal streams. The moment that the tidal current ceases is called slack water or slack tide. The tide then reverses direction and is said to be turning. Slack water usually occurs near high water and low water. But there are locations where the moments of slack tide differ significantly from those of high and low water.

Tides are commonly semi-diurnal (two high waters and two low waters each day), or diurnal (one tidal cycle per day). The two high waters on a given day are typically not the same height (the daily inequality); these are the higher high water and the lower high water in tide tables. Similarly, the two low waters each day are the higher low water and the lower low water. The daily inequality is not consistent and is generally small when the Moon is over the Equator. 

Definitions

From the highest level to the lowest:

• Highest astronomical tide (HAT) – The highest tide which can be predicted to occur. Note that meteorological conditions may add extra height to the HAT.

• Mean high water springs (MHWS) – The average of the two high tides on the days of spring tides.

• Mean high water neaps (MHWN) – The average of the two high tides on the days of neap tides.

• Mean sea level (MSL) – This is the average sea level. The MSL is constant for any location over a long period.

• Mean low water neaps (MLWN) – The average of the two low tides on the days of neap tides.

• Mean low water springs (MLWS) – The average of the two low tides on the days of spring tides.

• Lowest astronomical tide (LAT) and chart datum (CD) – The lowest tide which can be predicted to occur. Some charts use this as the chart datum. Note that under certain meteorological conditions the water may fall lower than this meaning that there is less water than shown on charts.

Current

The tides' influence on current flow is much more difficult to analyse, and data is much more difficult to collect. A tidal height is a simple number which applies to a wide region simultaneously. A flow has both a magnitude and a direction, both of which can vary substantially with depth and over short distances due to local bathymetry. Also, although a water channel's center is the most useful measuring site, mariners object when current-measuring equipment obstructs waterways. A flow proceeding up a curved channel is the same flow, even though its direction varies continuously along the channel. Surprisingly, flood and ebb flows are often not in opposite directions. Flow direction is determined by the upstream channel's shape, not the downstream channel's shape. Likewise, eddies may form in only one flow direction.

Nevertheless, current analysis is similar to tidal analysis: in the simple case, at a given location the flood flow is in mostly one direction, and the ebb flow in another direction. Flood velocities are given positive sign, and ebb velocities negative sign. Analysis proceeds as though these are tide heights.

In more complex situations, the main ebb and flood flows do not dominate. Instead, the flow direction and magnitude trace an ellipse over a tidal cycle (on a polar plot) instead of along the ebb and flood lines. In this case, analysis might proceed along pairs of directions, with the primary and secondary directions at right angles. An alternative is to treat the tidal flows as complex numbers, as each value has both a magnitude and a direction.

Tide flow information is most commonly seen on nautical charts, presented as a table of flow speeds and bearings at hourly intervals, with separate tables for spring and neap tides. The timing is relative to high water at some harbour where the tidal behaviour is similar in pattern, though it may be far away.

As with tide height predictions, tide flow predictions based only on astronomical factors do not incorporate weather conditions, which can completely change the outcome.

What are spring and neap tides?

A spring tide—popularly known as a "King Tide"—refers to the 'springing forth' of the tide during new and full moon.

A neap tide—seven days after a spring tide—refers to a period of moderate tides when the sun and moon are at right angles to each other.

A king tide is a non-scientific term that describes the highest high tides that occur along coastlines. These extreme tides cause unusually high water levels, often leading to coastal flooding, erosion, and other environmental impacts. While the term “king tide” is popular in the media and among the public, it does not have a precise scientific definition. Instead, it refers to the natural peak in the tidal cycle when the sun and moon’s gravitational forces align most strongly. 

King tides result from the combined gravitational forces of the moon and the sun on Earth’s oceans. While regular tides are the result of these gravitational interactions, king tides occur when the alignment and proximity of the moon and sun to Earth amplify these effects.

The main factors contributing to king tides include:

1. Lunar Perigee: This is the point in the moon’s elliptical orbit when it is closest to Earth. During perigee, the moon’s gravitational pull on Earth’s oceans is stronger, leading to higher tides.

2. Solar Perigee (Perihelion): This is the point in Earth’s orbit when it is closest to the sun, typically occurring in early January. The sun’s gravitational pull is stronger during this time, contributing to higher tides.

3. Syzygy: This term refers to the alignment of the Earth, moon, and sun. Syzygy occurs during new moons and full moons when the gravitational forces of the moon and sun combine to produce the highest tides, known as spring tides. King tides are extreme spring tides that occur when syzygy coincides with the lunar and solar perigees.

King tides occur when several specific conditions align:

• Full or New Moon: King tides usually occur during full or new moons, when the gravitational forces of the moon and sun work together to create higher tides.

• Lunar Perigee: If a full or new moon coincides with the moon being at its closest point to Earth, the tide is even higher.

• Solar Perigee: When Earth is closest to the sun, the sun’s gravitational effect on the tides is at its peak, further increasing tide levels.

• Local Topography and Weather: Local coastal features, weather patterns, and ocean currents also influence the height of king tides. Storm surges, strong winds, and atmospheric pressure exacerbate king tides, leading to more severe coastal flooding.

King Tide vs Spring Tide

All king tides are spring tides, but not all spring tides are king tides. King tides are the most extreme version of spring tides, occurring when additional factors such as the moon’s perigee and Earth’s perihelion combine to create the highest possible tide levels:

Spring Tide:

• Definition: A spring tide or syzygy tide occurs when the sun, moon, and Earth align during a full or new moon, which happens approximately twice a month. The term is not connected with the spring season, but instead relates to “springing forth” like a water spring or artesian well. The alignment of the sun, moon, and Earth amplifies the gravitational forces exerted on Earth’s oceans, leading to higher high tides and lower low tides than usual.

• Frequency: Spring tides occur twice a month, during every full and new moon.

• Magnitude: While spring tides are higher than normal, they are part of the regular tidal cycle and not necessarily extreme.

King Tide:

• Definition: A king tide is an informal term describing the highest of the high tides that occur during the year. King tides are extreme spring tides that usually occur when a spring tide coincides with the moon being at its closest point to Earth (lunar perigee) and/or when the Earth is closest to the sun (perihelion).

• Frequency: King tides typically occur twice a year, during specific times when the gravitational forces of the moon and sun are particularly strong.

• Magnitude: King tides are the most extreme high tides, much higher than regular spring tides.

Three basic tidal patterns occur along the Earth’s major shorelines. In general, most areas have two high tides and two low tides each day. When the two highs and the two lows are about the same height, the pattern is called a semi-daily or semidiurnal tide. If the high and low tides differ in height, the pattern is called a mixed semidiurnal tide.

Some areas, such as the Gulf of Mexico, have only one high and one low tide each day. This is called a diurnal tide. The U.S. West Coast tends to have mixed semidiurnal tides, whereas a semidiurnal pattern is more typical of the East Coast (Sumich, J.L., 1996; Thurman, H.V., 1994; Ross, D.A., 1995).

Diurnal tide cycle (upper left). An area has a diurnal tidal cycle if it experiences one high and one low tide every lunar day. Many areas in the Gulf of Mexico experience these types of tides.

Semidiurnal tide cycle (upper right). An area has a semidiurnal tidal cycle if it experiences two high and two low tides of approximately equal size every lunar day. Many areas on the eastern coast of North America experience these tidal cycles.

Mixed Semidiurnal tide cycle (lower middle). An area has a mixed semidiurnal tidal cycle if it experiences two high and two low tides of different size every lunar day. Many areas on the western coast of North America experience these tidal cycles.

Biological aspects

Intertidal ecology

Intertidal ecology is the study of ecosystems between the low- and high-water lines along a shore. At low water, the intertidal zone is exposed (or emersed), whereas at high water, it is underwater (or immersed). Intertidal ecologists therefore study the interactions between intertidal organisms and their environment, as well as among the different species. The most important interactions may vary according to the type of intertidal community. The broadest classifications are based on substrates — rocky shore or soft bottom.

Intertidal organisms experience a highly variable and often hostile environment, and have adapted to cope with and even exploit these conditions. One easily visible feature is vertical zonation, in which the community divides into distinct horizontal bands of specific species at each elevation above low water. A species' ability to cope with desiccation determines its upper limit, while competition with other species sets its lower limit.

Humans use intertidal regions for food and recreation. Overexploitation can damage intertidals directly. Other anthropogenic actions such as introducing invasive species and climate change have large negative effects. Marine Protected Areas are one option communities can apply to protect these areas and aid scientific research.