Tides and Tidal Current

Mains Marks Booster     5th August 2023        
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Introduction:

  • Tides are long-period waves that roll around the planet as the ocean is pulled by the moon's and sun's gravitational forces. They are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon, the Sun, and the rotation of the Earth.
  • Tides are driven primarily by the gravitational interaction between Earth and the Moon, with the Sun also playing a smaller but significant role. 

Relationship Between Gravitational Forces and Tides

  • The creation of tides involves a delicate interplay between the gravitational forces of the Earth, Moon, and Sun. While gravity acts to pull objects toward one another, the centrifugal force acts to push them apart.
  • The Moon's gravitational pull is strongest on the side of the Earth that happens to be facing the Moon, causing the water in the oceans to bulge out in the direction of the moon. T
  • his creates a high tide. At the same time, another high tide occurs on the opposite side of the Earth due to the centrifugal force created by the Earth spinning on its axis. The areas in between these bulges experience low tide.
  • The position of the Sun relative to the Moon and Earth also influences the tides.
  • When the Moon and Sun align (at the new moon or full moon), their gravitational forces combine to create higher high tides and lower low tides, known as spring tides.
  • When the Moon and Sun are at right angles to each other (first quarter and last quarter moon), their gravitational forces partially cancel each other out, resulting in neap tides, where the difference between high and low tides is smallest.
Relationship Between Gravitational Forces and Tides

Tidal Currents

  • Tidal currents are the horizontal movement of water caused by the rising and falling of the tides. As the tide rises, water moves towards the coast, causing a "flood current."
  • Conversely, as the tide falls, water moves back towards the sea, causing an "ebb current." In some locations, there is a period of little or no current at high or low tide, known as "slack water." 

Types of Tides

Based on Frequency

Tides can be categorized based on their frequency:

  • Semi-diurnal Tides: These occur twice daily and are common in the Atlantic Ocean. They result in two nearly equal high tides and two low tides each day.
  • Diurnal Tides: These occur once daily and are common in some locations in the Gulf of Mexico and the western Pacific Ocean. They result in one high tide and one low tide each day.
  • Mixed Tides: These occur twice daily and are common in the Pacific Ocean. They result in two unequal high tides and two unequal low tides each day. 

Based on the Sun, Moon, and Earth (SME) Position

Tides can also be categorized based on the relative positions of the Sun, Moon, and Earth:

  • Spring Tides: Spring tides occur when the Sun, Moon, and Earth are aligned (during the full moon and new moon). The combined gravitational effect of the Moon and Sun leads to higher high tides and lower low tides.
  • Neap Tides: Neap tides occur when the Sun and Moon are at right angles to each other (during the first and last quarter moon). The gravitational forces partially cancel each other out, resulting in less extreme tides.

Types of Tides

Importance of Tides

Tides have a significant impact on our planet and daily life. They influence coastal ecosystems, assist in navigation, influence human activities like fishing and surfing, and even have potential for renewable energy generation.

  • Ecological Importance: Tides are crucial to the health of many coastal and marine ecosystems. They influence the distribution of organisms, nutrients, and oxygen in these ecosystems, and they create unique habitats like intertidal zones, which support a wide variety of life forms.
  • Navigation: For hundreds of years, tides have played a crucial role in navigation. Knowledge of tides is essential for safe and efficient navigation, particularly in coastal waters.
  • Fishing and Recreation: Tides can influence the best times for fishing and surfing. Certain fish are more active during particular tide stages, and tidal currents can create ideal wave conditions for surfing.
  • Renewable Energy: Tidal movements hold potential for renewable energy generation. Tidal energy is predictable and can generate significant power. Tidal turbines and tidal barrage power plants are two examples of how we can harness this energy. 

Conclusion:

Tides are a complex yet fascinating phenomenon resulting from the gravitational interactions between the Earth, Moon, and Sun. Their impact extends beyond the simple rise and fall of sea levels, influencing diverse ecological systems, human activities, and even renewable energy production.

Samadhaan