Saturday, January 30, 2010

High tides

Images source Keith Cool: HERE
The full moon was at 1:17 this morning, according to the Times.  What does that mean for the tides?   They will be at the high end of the range.  and that is the case according to the charts: 5.7 feet at The Battery, 8.7 at Kings Point, 11.4 at Friendship Harbor in Maine.  The high end of normal.

Notice in the animated image above that at the half moon the image is round.  These are the neap tides.  Tides are low.  At the full and new moon the oceans bulge out, attracted to the moon and sun.  Tides are high.

Last night a kayaker told us that today is a proxigean high tide (when the moon is extremely close to the earth and the sun is on the same side).  Maybe - but I couldn't find anyone predicting that we are at such an unusual astronomical event - maybe it's just the ordinary monthly perigee.

Another image from Keith Cool - Halls Harbor, Nova Scotia, on the Bay of Fundy shows the dramatic (20 feet +/-) in a six and a half hour period: