There are a few reliable phenomena in the world. The Sun rises to the east and sets to the west. The stars come out at night. And the tides regularly rise and fall.
Tides are long-period waves that move through the oceans in response to the forces exerted by the Moon. Tides arise in the oceans and headway toward the coastlines, where they appear as the regular rise and fall of the sea surface.
There are variations in height between the low and high tides as the moon waxes and wanes from new to full and vice versa. Primarily, the Moon and Sun are responsible for the rising and falling of ocean tides. In most places, there are two low tides and two high tides a day.
However, there are specific spots on the Earth’s surface where the height of the tides and their fluctuation in time is affected by several factors. For example, the shape of the specific beach, the angle of the seabed leading up to the beach, and more extensive coastline and the prevailing ocean currents and winds.
High tide happens when the highest part, or crest, of the wave reaches a particular location. On the other hand, low tide corresponds to the lowest part of the wave, or its trough. The difference in the height of high tide and the low tide is called the tidal range.
The rise and fall of the tides have an essential role in the natural world and can have a marked effect on maritime-related activities.
How the Moon affects the tides.
Both Moon and Sun influence the ocean tides, but the Moon plays the most prominent role. The Moon, specifically its gravitational pull, makes the water in the oceans bulge, thus changing tides height.
The Moon, with an average of 238,855 miles away from Earth (about 30 Earth away), is closer to our planet than the Sun, which is approximately 93,000,000 miles (150 million kilometers) away. It is why the tidal effect of the Moon on Earth is more than twice more potent than the Sun, despite the Sun’s gravitational pull on Earth around 178 times stronger than that of the Moon.
Here’s how it works:
The Moon’s gravitational pull is the strongest on Earth’s side that is directly facing the Moon. Thus, the water on that side is pulled forcefully towards the Moon. On the contrary, the Moon’s gravitational pull is at its weakest on Earth’s side, farthest from the Moon. The average gravitational pull of the Moon on the planet is at the center of the Earth.
To calculate the tidal force, subtract the average gravitational pull from the Earth from the gravitational pull at each location on Earth.
How does the Sun affect tides?
The Sun also causes tides, although they are somewhat smaller than the Moon. Extreme tides happen when the Sun lines up with the Moon and the Earth, and when lunar and solar tides act against each other, the result is unusually small tides, called neap tides.
What role did the Sun have in early 2019?
Every early January, the tides are strongest because the Earth is closest to the Sun.
We had reached Earth’s closest point to the sun on January 3, 2019, at 5:20 UTC. Astronomers call this perihelion, special point in our orbit. It came from the Greek roots ‘peri’ meaning near and ‘helios’ meaning sun.
Why does a supermoon cause more extreme tides?
We expect a supermoon to happen when a full moon or new moon closely aligns with perigee or the moon’s closest point to Earth in its monthly orbit. It causes extra-large spring tides or also called perigean spring tides. During this time, the Earth’s oceans are feeling the most powerful pull of the moon’s gravity.
Are there extra-high tides on the exact day a supermoon happens? Probably not. The supermoon, any full moon, is followed by the highest tides by a day or two.
Are the most extreme high tides always happen during supermoons? Not necessarily. When a spring tide happens simultaneously as heavy winds and rain and flooding due to a weather extreme, extreme flooding occurs.
We had experienced “season” of 3 (full moon) supermoons. On March 9, April 7-8, and May 7, 2020. It is expected that we will have a “season” of 3 (new moon) supermoons on September 17, October 16, and November 15, 2020.