Tides are caused by the gravitational pull of the moon and sun on the Earth's oceans. This causes the ocean levels to rise and fall, creating high tides and low tides approximately every 12 hours on opposite sides of the globe. Spring tides occur during a full moon or new moon and have the highest tidal ranges, while neap tides happen midway between spring tides and have the lowest tidal ranges. Different types of tides are caused by the relative positions of the Earth, moon, and sun.

1. Tides By Emily and Nicole

8. Other Pictures When the Sun and Moon form a right angle, as when we see a half moon, their pulls fight each other and we notice a smaller difference between high and low tides. These are called neap tides. When the Moon, Earth, and Sun fall in a straight line, which we call syzygy ( siz -eh-gee), we notice the greatest difference between high and low tide water levels. These spring tides occur twice each month, during the full and new Moon. If the Moon is at perigee, the closest it approaches Earth in its orbit, the tides are especially high and low.

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