Tides are the periodic rise and fall of the ocean surface occurring once or twice in a 24 hour period. Due to a combination of the gravitational attraction of the Moon and Sun together form a bulge of water on the side facing the Moon. While on the side of the Earth, facing away from the Moon, a bulge of water also forms due to completely different reasons. The gravitational pull of the Moon here is weaker than anywhere else and water is not attracted as strongly as the Earth.
The entire Earth, being one solid mass, is pulled by the Moon, but the water farthest from the Moon gets pulled the least. The Earth is literally pulled away from the water, which creates a second bulge on the opposite side of the Earth.
Alignment of the Moon and Sun produce gravitational forces that result in exceptionally high tides called spring tides. Spring tides occur once every 14 days. King tides, on the other hand ,are a type of spring tide but occur twice a year and create higher than normal tides. A king tide comes about when the Sun, Moon and Earth are aligned thus generating a greater than normal gravitational pull which creates higher tides.
Smaller tides occur when the the Moon and the Sun are at right angles to each other and their gravitational forces somewhat oppose each other. Such tides are known as neap tides.
Because the tidal bulge is inclined relative to the Earth's equator, different parts of the Earth experience a different tidal height at each rotation of the Earth.
When a land mass at the surface of the Earth lines up with the Sun and Moon, as shown on the right, the water around that land mass is at high tide. When the land mass is at right angles to the Sun and Moon the water around it is at low tide. So every land mass is exposed to two low and two high tides every 24 hour period.
Both the Moon and the Sun play a key role in the production of a tidal force that causes the tides on Earth. Even though the Moon has only one hundredth the mass of the Earth it plays a key role in the production of tides on Earth because it is so close and therefore its gravitational force is able to attract the water on Earth more strongly than the Sun.
When will a land mass experience a spring tide?
Explain how a spring tide comes about.
One side of the Earth has a high tide while the other side experiences
When does a land mass experience a low tide? Explain.
Both the Sun and the Moon contribute to the formation of a tidal force. This tidal force causes tides to occur on Earth. Which is more significant in contributing to the tidal force the Moon or the Sun?
Explain why each land mass experiences two tidal periods every rotation.
Which land masses will experience a low tide?
When the Moon and the Sun are in the positions shown on the right then
The fisherman pictured on the right is fishing for a predatory fish that comes close to shore during high tide. Whiting and Bream are two such predatory fish. Is the fisherman more likely to catch a Bream tonight? Explain.
A small fishing boat has run aground. The owner is waiting for low tide to rescue the boat. On a particular night there is no Moon in the sky. Should she go down to the rocks and attempt to rescue the boat? Explain. Consider the animation on the right before answering.
