Spring and neap tides are caused by the gravitational pull of the Moon and the Sun on Earth's oceans.
Spring Tides:
- When: Occur during the full moon and new moon phases.
- Causes: During a full moon, the Earth is between the Sun and the Moon. During a new moon, the Moon is between the Earth and the Sun. In both cases, the gravitational forces of the Sun and Moon align, pulling the ocean water in the same direction. This results in higher high tides and lower low tides.
- Impact on Earth: The ocean water is pushed more towards the shore, causing extreme tides. The Earth's crust also experiences small deformations due to these gravitational forces.
Neap Tides:
- When: Occur during the first and third (last) quarter moon phases.
- Causes: During these phases, the Moon and the Sun are at right angles relative to the Earth. Their gravitational pulls counteract each other, resulting in not as much difference between high and low tides. This causes lower high tides and higher low tides.
- Impact on Earth: The tidal range is smaller, so the ocean water is less extreme in its movement. The Earth's crust experiences less stress compared to spring tides.
In summary, spring tides occur during the full and new moons when the Sun and Moon's gravitational effects combine, while neap tides occur during the quarter moons when their effects counterbalance each other.