A Neap tide in costal Louisiana produces 2 high and 2 Low tides very quickly in a 24 hr period, yet all other days we have one high and one low. Why does this happen?

Question

I’m familiar with neap tides. It’s my understanding that they occur when the sun, moon, and earth form right angles and the moon phase is at 1/4 and 3/4. Yet this occurrence happens on a waning or waxing gibbous every time. The range is very small and changes quickly. I can’t wrap my head around the science that produces a completely different tidal sequence twice a month, then what you would see play out on any other day

In: Earth Science

Answer 1

Part of your premise is incorrect- there are two tide cycles per day all through the month on just over a 12 hour cycle. If you look up tide charts in your local area you should see this – each day has am and pm high/low tides, with a few exceptions when the am tide is near noon, pushing the next tide cycle into the next day

With a neap tide the gravity from the moon is pulling the water at right angles to the direction it’s being pulled by the gravity of the sun, so you get smaller tides.

With spring tides the moon is aligned with the sun so they’re both pulling the water in the same direction, causing larger tides.