Why does a wave close out?

Question

Like when it breaks at the same time all along its length.

Answer 1

it's coming in perpindicular to the bar thats making it break.  waves need to come in obliquely-- like around a point, or across a formed sand bar, or along a reef.  if it comes head-on, the whole length is pushed up in unison, rather than peeling sequentially.

Answer 2

because of a sandbar or when it get close enough to shore, or if there is a reef it breaks

Answer 3

The shape and length of the sandbar/reef and the direction of the swell will cause a close out. The swell hitting the sandbar/reef at an angle has less of a chance to close out.  Straight on, the swell will peek and break in long lines making it almost impossible to ride anything but froth.

Answer 4

I don't really know but it seems like logic. The wave can't stay open forever. Gravity must push it down.

Answer 5

shallow water under the wave pushes it up to hight i assume and it hasnt and it toppels over on it self. a wave starts peeling in the shallowest part of the water. so for it to close out all the water is suddenly shallow along the line so it ramps and dumps

Answer 6

Everything that helps make a wave can also cause the same wave to closeout depending on conditions.  To answer you question, it would be: swell direction, bottom contour (reef, rock, sandbar, etc), wind direction, etc.  It's the main reason we play so much attention the weather reports in trying to determine the best location to surf.

Beach breaks tend to change also since they have a sand bottom.  What might have been ideal conditions 3 years ago may not be the case this weekend.  Reefs/points are consistant since the bottom never or rarely changes.