Why do the highest diurnal tides occur approx. two days AFTER full or new moon and not on the day itself?

Question

At least on the Eastern Atlantic Seaboard our tide tables always tell the same story: Full Moon, New Moon, go down the list two days and find the highest (and lowest) tidal heights. Why does this not happen before, when - presumably - the moon exerts more power? Thank You.

Answer 1

The tides are caused by the Moon's angular position relative to the Earth and Sun, and so are the phases of the Moon. It may seem that the Moon being full or new causes a higher tide, but it's really the fact that the times when the Moon is positioned to reflect the Sun's light either directly towards (full) or directly away (new) from the Earth are also the times when the Moon and Sun form a line with the Earth, combining their tidal effects for maximum strength.

As for the two day delay, this is a result of the fact that the Earth's tides actually move as a wave across the entire, interconnected world ocean. It starts in the Southern Ocean, the only place on Earth where a wave can travel around the world unimpeded. It then moves northward, and takes up to two days to reach every point. The data seems to suggest that it should reach the North American Atlantic coast in one day, not two, but perhaps you have some local geography that delays it.

Answer 2

in case you have been stopped in direction of the sea in the tropics, the tidal bulge might pass you two times: in simple terms after the Moon's top transit (meridian passage) and in simple terms after the sunlight's top transit (at which era the Moon is around decrease transit). the reason it quite is not immediately below the Moon (plus the antipodal factor) is Earth's rotation that drags the tidal bulge easttward (the rotation is eastward and the shallow sea bottoms sluggish the form of the bulges at particular places, so as that they lag the Moon's meridional projection). notwithstanding, close to coasts, it isn't any longer the tidal bulge that create the tides, yet a wave of capability created by the bulge: the form of the backside and the form of the coast itself will influence how this wave travels. The Bay of Fundy is quite short (while positioned next to Earth's circumference) and it is open on the west end. The theoretical tidal bulge travels west ward (alongside with the plain action of the Moon) so the bulge itself can not enter the bay. yet it quite is the place the international's optimal tides are got here across. The capability carried to the mouth of the Bay by the bulge is going up the Bay as a wave of capability. the form of the Bay is that of a funnel so as that the capability point of the wave will enhance even nevertheless the finished capability decreases by way of fact the wave advances. yet another occasion is the Gulf of St. Lawrence. The bulge creates the capability wave that enters at Cabot Strait. The wave advances northward, alongside the West coast of Newfoundland, the North Shore of Quebec, Gaspe, New Brunswick, Nova Scotia... The wave takes any such long term to flow around the Gulf that a sparkling wave has began in. It does no longer remember what time of day it is (relative to the Moon's place), there is often in the Gulf a minimum of one spot the place it is severe tide and one the place it is low tide, on the comparable time. it is even achievable, in case you p.c.. the wonderful circumstances, to locate those 2 spots on the comparable longitude (as a result on the comparable perspective relative to the Moon's place). by way of fact of this it is complicated, on a coast, to wager the time of severe tide (or low tide) based basically on the situation of the Moon (and sunlight).

Answer 3

I've noticed this as well. I think that the position of the moon is more important than the phase. Also, maybe because water is so dense, there may be an inertia that needs to be overcome.

Answer 4

It depends on how close the moon is, not on how the sunlight is hitting it.