Final answer:
Tides are the periodic rise and fall of sea levels caused by the Moon's and Sun's gravitational forces.
The strength of the tides changes throughout the month, influenced by the positions of these celestial bodies, and is also affected by local geographical features.
Step-by-step explanation:
Tides are the alternate rising and falling of sea level that we observe on Earth's shores. This phenomenon is primarily caused by the gravitational pull of the Moon, and to a lesser extent, that of the Sun.
As the Moon exerts its gravitational force on Earth, it pulls the water towards it, creating what is known as a tidal bulge. Since Earth is rotating and the position of the Moon and Sun relative to Earth changes, the locations of these bulges change, resulting in the cyclical nature of tides.
Moreover, the amplitude of tides changes over the course of a month due to the changing positions of the Moon and Sun in relation to Earth. When aligned, they cause higher spring tides, and when at right angles, they result in lower neap tides.
The complexity of tides is further influenced by the topography of coastlines, the bathymetry of the ocean floor, land masses, and oceanic friction.
This explains the variations in tide magnitude across different locations. Places like the Bay of Fundy in Canada are famous for their dramatic tidal ranges, while other areas may experience much smaller tidal changes.