Friday, August 29, 2014

Tides ( Moon and Earth's phenomenal changes )

“I derive from the celestial phenomena the forces of gravity with which bodies tend to the
sun and several planets. Then from these forces, by other propositions which are also
mathematical, I deduce the motions of the planets, the comets, the moon, and the sea.”                                                                                                   —SIR ISAAC NEWTON

Tides are the periodic raising and lowering of average sea level that occurs throughout the ocean. As sea level rises and falls, the edge of the sea slowly shifts landward and seaward daily, often destroying sand castles built during low tide. Knowledge of tides is important in many coastal activities, including tide pooling, shell collecting, surfing, fishing, navigation,and preparing for storms. Tides are so important that accurate records have been kept at nearly every port for several centuries and there are many examples of the term tide in everyday vocabulary (for instance, “to tide someone over,” “to go against the tide,” or to
wish someone “good tidings”).

Firstly, early coastal peoples noticed the tides yet the earliest written record of tides is in about 450 B.C. Even the earliest sailors knew the Moon had some connection with the tides because both followed a similar cyclic pattern. However, it wasn’t until Isaac Newton (1642–1727) developed the universal law of gravitation that the tides could adequately be explained.

Although the study of the tides can be complex, tides are fundamentally very long and regular shallow-water waves. Their wavelengths are measured in thousands of kilometers and their heights range to more than 15 meters (50 feet).
*Interesting Fact : 
     1."16.27 metres (or 53.38 feet) between high and low tide at Burncoat Head in the Bay of Fundy's Minas Basin, Nova Scotia is the highest tidal point in the world." 
     2.High tides happen every 12 hours and 25 minutes (or nearly an hour later each day) because of the changing position of the Moon in its orbit around the Earth. 
     3.At mid-tide, the flow in Minas Channel north of Blomidon equals the combined flow of all the rivers and streams on Earth!

What Causes the Tides? 

Simplistically, the gravitational attraction of the Sun and Moon on Earth creates ocean tides. In a more complete analysis, tides are generated by forces imposed on Earth that are caused by a combination of gravity and motion among Earth, the Moon,and the Sun.
  
Characteristics of Tides:

Tidal 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.

 


Types of Tides:  
There are different types of Tides on the basis of movements of Moon,Earth & Sun:- 

1.Spring Tide-

When the gravitational effects of the Sun and the Moon combine, we get spring tides, which have nothing to do with the season of spring. The term refers to the action of the seas springing out and then springing back. These are times of high high tides and low low tides.
In this phase position of Earth, Moon and Sun will be in a straight line . There is two cases - one is when Moon is in between Sun and Earth and the second is in which Earth is in between Moon and Sun .That means the angle between all three will be 180 degree .

 Higher tides occur during these Moon phases because the Sun also exerts a gravitational pull on our oceans, although it is only 46 percent as strong as the Moon's.

 A. Case - 1 : Full Moon : When the Earth will be in line with Moon and Sun and also in between the Moon and Sun then it will be called as Full Moon .

  B. Case - 2 : New Moon : When the opposite will happen i.e the Moon will be in between the Earth and Sun then it is called as New Moon phenomenon.

2.Neap Tide-

A tide in which the difference between high and low tide is the least.Neap tides
occur twice a month when the Sun and Moon are at right angles to the Earth.

When this is the case, their total gravitational pull on the Earth's water is weakened because it comes from two different directions.

When the Moon is at first quarter or third quarter, the sun and Moon are separated by 90° when viewed from the Earth, and the solar tidal force partially cancels the Moon's. At these points in the lunar cycle, the tide's range is at its minimum.


Best pdf on Tides ... Must read ... Click here to download .......

Importance of Tides:

1.Fishing : Fish may concentrate during ebb tides. Commercial fishermen follow the tides and learn to fish during levels of highest concentration to improve their economic investment and to make more efficient use of their time. Recreational fishermen may also fish during ebb tides because the concentrations of smaller fish attract the larger trophy fish. Tides affect other aspects of oceanic life, including the reproductive activities of fish and ocean plants. Floating plants and animals ride the tidal currents between the breeding areas and deeper waters. The tides help remove pollutants and circulate nutrients ocean plants and animals need to survive. 

2.Tidal Zone Foods:Crabs, mussels, snails, seaweed and other edible sea life inhabit the tidal zone. Small tide pools may also contain small fish and sea vegetables. The sea life found in these regions are often harvested for food. Without the regular washing of the tides, these complex and abundant creatures would die and food resources would diminish.
 
3.Navigation:Tides affect the depth and currents in and around coastal areas. Ships may need to navigate the waters during high tide in some areas or risk running aground. Pilots take into consideration the water level, width of channels and direction of the water flow to determine the best time to travel. Pilots may choose to travel when tides are at ebb in order to get tall loads under bridges.Tidal flows can also help or impede the progress of a ship in the water. Pilots can take advantage of the current to get the craft where it needs to go. A thorough understanding of how tides affect navigation and how to use the tides in navigation can improve the productivity of marine and inland shipping. 

4.Weather:Tides and tidal currents affect the weather by stirring the ocean waters. The tides and tidal currents mix arctic water that can't absorb lots of sunlight with warmer topic water that does. The stirring produces more predictable and habitable climate conditions and balances temperatures on the planet. 

5.Tidal Energy:Two high tides and two low tides occur during every 24-hour period. The predictability of the tides, fast movement of water during the inflow and outflow can provide a source of renewable energy to communities living along the coast. Hydroelectric plants can exploit the water flow in ways similar to those used on rivers.










  1.  fish.
    • Tides affect other aspects of oceanic life, including the reproductive activities of fish and ocean plants. Floating plants and animals ride the tidal currents between the breeding areas and deeper waters. The tides help remove pollutants and circulate nutrients ocean plants and animals need to survive.

    Tidal Zone Foods

    • Crabs, mussels, snails, seaweed and other edible sea life inhabit the tidal zone. Small tide pools may also contain small fish and sea vegetables. The sea life found in these regions are often harvested for food. Without the regular washing of the tides, these complex and abundant creatures would die and food resources would diminish.

    Navigation

    • Tides affect the depth and currents in and around coastal areas. Ships may need to navigate the waters during high tide in some areas or risk running aground. Pilots take into consideration the water level, width of channels and direction of the water flow to determine the best time to travel. Pilots may choose to travel when tides are at ebb in order to get tall loads under bridges.
      Tidal flows can also help or impede the progress of a ship in the water. Pilots can take advantage of the current to get the craft where it needs to go. A thorough understanding of how tides affect navigation and how to use the tides in navigation can improve the productivity of marine and inland shipping.

    Weather

    • Tides and tidal currents affect the weather by stirring the ocean waters. The tides and tidal currents mix arctic water that can't absorb lots of sunlight with warmer topic water that does. The stirring produces more predictable and habitable climate conditions and balances temperatures on the planet.

    Tidal Energy

    • Two high tides and two low tides occur during every 24-hour period. The predictability of the tides, fast movement of water during the inflow and outflow can provide a source of renewable energy to communities living along the coast. Hydroelectric plants can exploit the water flow in ways similar to those used on rivers.



Read more : http://www.ehow.com/info_7751713_importance-tides.html

Fishing

  • Fish may concentrate during ebb tides. Commercial fishermen follow the tides and learn to fish during levels of highest concentration to improve their economic investment and to make more efficient use of their time. Recreational fishermen may also fish during ebb tides because the concentrations of smaller fish attract the larger trophy fish.
    Tides affect other aspects of oceanic life, including the reproductive activities of fish and ocean plants. Floating plants and animals ride the tidal currents between the breeding areas and deeper waters. The tides help remove pollutants and circulate nutrients ocean plants and animals need to survive.


Read more : http://www.ehow.com/info_7751713_importance-tides.html


  1. Fishing

    • Fish may concentrate during ebb tides. Commercial fishermen follow the tides and learn to fish during levels of highest concentration to improve their economic investment and to make more efficient use of their time. Recreational fishermen may also fish during ebb tides because the concentrations of smaller fish attract the larger trophy fish.
      Tides affect other aspects of oceanic life, including the reproductive activities of fish and ocean plants. Floating plants and animals ride the tidal currents between the breeding areas and deeper waters. The tides help remove pollutants and circulate nutrients ocean plants and animals need to survive.

    Tidal Zone Foods

    • Crabs, mussels, snails, seaweed and other edible sea life inhabit the tidal zone. Small tide pools may also contain small fish and sea vegetables. The sea life found in these regions are often harvested for food. Without the regular washing of the tides, these complex and abundant creatures would die and food resources would diminish.

    Navigation

    • Tides affect the depth and currents in and around coastal areas. Ships may need to navigate the waters during high tide in some areas or risk running aground. Pilots take into consideration the water level, width of channels and direction of the water flow to determine the best time to travel. Pilots may choose to travel when tides are at ebb in order to get tall loads under bridges.
      Tidal flows can also help or impede the progress of a ship in the water. Pilots can take advantage of the current to get the craft where it needs to go. A thorough understanding of how tides affect navigation and how to use the tides in navigation can improve the productivity of marine and inland shipping.

    Weather

    • Tides and tidal currents affect the weather by stirring the ocean waters. The tides and tidal currents mix arctic water that can't absorb lots of sunlight with warmer topic water that does. The stirring produces more predictable and habitable climate conditions and balances temperatures on the planet.

    Tidal Energy

    • Two high tides and two low tides occur during every 24-hour period. The predictability of the tides, fast movement of water during the inflow and outflow can provide a source of renewable energy to communities living along the coast. Hydroelectric plants can exploit the water flow in ways similar to those used on rivers.



Read more : http://www.ehow.com/info_7751713_importance-tides.htm
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