Ebb (also known as ebb and flow) is the name given to the tidal phase when the water level falls. The opposite of ebb is flood tide, when the water level rises. Ebb tide typically occurs during the day, while flood tide happens at night.
The word “ebb” comes from Old English ebba, which means “flowing out.” The word “flow” comes from Proto-Germanic *fluwaz, which also means “flowing out.” Both words are ultimately derived from Proto-Indo-European *pleu-, which means “to flow.”
Ebb tides occur because the Earth’s rotation creates a bulge in the oceans near the equator. This bulge is caused by centrifugal force, which is greater at the equator than it is at the poles. As a result, there is more water on one side of the planet than there is on the other.
When this bulge aligns with the Moon’s gravity, it creates a high tide. When it doesn’t align with the Moon’s gravity, it creates a low tide. Since there are two high tides and two low tides every day, this means that there are two ebb tides and two flood tides every day as well.
The strength of an ebb tide depends on how much water is flowing out during that particular cycle. If there isn’t much water flowing out, then it’s called a weak ebb tide. If there’s a lot of water flowing out, then it’s called a strong ebb tide.