The time table of high and low tide - Does anybody physically check it out ?

Question

We get time table about the high and low tide as well as the height of the high tide on differenct dates and times. Do we have a system to actually measure up the actual sea level to confirm that what we have predicted / mathemically calculated is actually coming out true. I have my own doubts. I have on several occasions tried to check it out myself and did NOT get any convincing results. I am a layman, not a scientist. It is my curiosity. I have a strong gut feeling that there are also other forces which also significantly influence the high tides and we do not know all of them. If we present the comparative data of the actual sea level at different time and location zones, we will get better picture. It is so obvious, but it is also likely to be taken for granted by the scientists. Do not get offended.

Answer 1

Yes, there is a site where you can check the buoy data. I think these buoy measured and collected data should provide you with the information you need to check how accurate the forecast times of high and low tide.

http://www.ndbc.noaa.gov/hmd.shtml

Answer 2

intense and espresso tides ought to do with gravitational pull from the moon. For length think ofyou've got to learn the community section you're inquisitive about, because length, adjustments in feet from intense to low or perhaps what percentage time the tides replace in an afternoon has to do with area. For the posters above both intense tides an afternoon isn't well-known some places merely have one. And the circumstances replace steadily because the days pass. midday should not be hight tide next week even if it really is intense tide at midday on the instant.

Answer 3

My previous answer may have helped in answering this question (if you could make sense of my ramblings).

Tides are affected by different factors and some of these can be very accurately predicted, others can't be predicted.

The movement of the moon and earth around the sun can be calculated with a great degree of accuracy and if these were the only factors influencing tides it would be possible to predict tidal levels with accuracy well into the future.

There are more localised factors which can't be predicted - namely air pressure and wind. As pressure drops there's less force pressing down onto the seas and oceans which causes an upwelling of the water, roughly 1 millibar change in aire pressure creates a 10mm change in sea levels. Here in the UK this can affect sea levels by about a metre - from the lowest pressure to the highest pressure.

Another important factor is wind. If it's blowing landwards from the seas and oceans it pushes the water along in front of it, conversely if it's blowing from land to sea it has the effect of blowing the water away.

Winds are the result of differnces between air pressure with air masses moving from high pressure areas to low pressure ones. The more pronounced the differnce in pressure the stronger the winds - you'll have seen the weather charts with isobars on them, the tighter the isobars the windier it is.

So these two unpredictable factors in tidal calculations go hand in hand. The worst thing that can happen is an area of very low pressure with strong winds blowing in from the sea - this 'sucks up' the sea level and drives it forward at the same time.

Typically in the UK the variation from predicted high and low tides could be by as much as a metre (more in places with large tidal ranges, less in others).

We do know all the forces affecting high and low tides, it's just that we can't predict some of them well in advance.

Again, e-mail if more details required.

Answer 4

You are right that it is complex. The tides are produced both by the gravitational attraction of the sun and moon and depends on their relative positions in the sky. This also changes seasonally with the tilt of the earth. An important factor is the shape of the shore where a bay can concentrate the tidal effects (see Bay of Fundy). Islands in the Caribbean have small tides because the water is free to flow around them. Major ports have tidal gages that are used to record the heights of the tides. Tidal charts can be prepared from historical averages for sun and moon positions but even the weather (strong winds) can affect actual observed the tides.

Answer 5

NOAA's National Ocean Service (NOS) has been studying the tides and ocean levals for many years now this link
http://www.nos.noaa.gov/topics/navops/ports/welcome.html
is a great resorce for learning more about tides and currents of the world.