Tides, they are a changin'

Please pardon the tacky pun regarding the over-played favorite by Bob Dylan.

We're experiencing the tail end of a spring tide, when the tides are unusually high and low. This occurs when the earth, sun and moon are all in-line during the new and full moons. At these two lunar phases, large bodies of water are pulled by the combined gravitational forces of the sun AND moon, thus creating extreme high tides. It has nothing to do with the seasons...does anyone know why it's called 'spring?'

Taken yesterday (10.1.11) Here, the high spring tide almost breaches the breakwater. During hurricane Irene, the higher-than-usual tide swelled into the parking lot.

Close-up of the tidal action.

Another parking lot view.

Conversely, the dramatically low tide:

 

lowest of the low...notice where the dock usually floats on the mooring...basically at the top of the green algae.

I rooted around my stored photos trying to find an example of a "normal" high tide. This is the best example I found, taken several days before the full moon. It's not the best example (as the tide is still higher-than-normal) but, at least, offers some comparison.

Looking toward the railroad bridge and the canal.

The opposite extreme also exists. Neap tides occur when the moon is perpendicular to the earth during the waning or waxing quarter phase (towards full and new). During a neap tide, the gravitational pull is not as strong, and the tides do not exhibit dramatic changes. I'll try and post examples of neap tides in the marina. The NOAA website animated the effects of gravity on the tides: http://oceanservice.noaa.gov/education/kits/tides/tides06_variations.html. It's a great little site!