What do the seconds mean for wave height??

Question

http://www.morebeach.com/surf_forecasts/maine/higginsbeach.html

i was just wondering what the seconds mean or indicate

Answer 1

The seconds for wave height simply mean the seconds from one wave to the next.  For example if a four wave height is reported every 7 seconds, on average, a 4 foot wave passes the measuring device approximately every 7 seconds.  According to Wikipedia, this is how a wave frequency is calculated:

By timing

To calculate the frequency of an event, the number of occurrences of the event within a fixed time interval are counted, and then divided by the length of the time interval.

In experimental work (for example, calculating the frequency of an oscillating pendulum) it is more accurate to measure the time taken for a fixed number of occurrences, rather than the number of occurrences within a fixed time. The latter method introduces — if N is the number of counted occurrences — a random error between zero and one count, so on average half a count, causing an biased underestimation of f by ½ f / (N + ½)[citation needed] in its expected value. In the first method, which is more accurate, frequency is still calculated by dividing the number of occurrences by the time interval; however it is the number of occurrences that is fixed, not the time interval.

An alternative method to calculate frequency is to measure the time between two consecutive occurrences of the event (the period T) and then compute the frequency f as the reciprocal of this time:

    f = \frac{1}{T}.

A more accurate measurement can be obtained by taking many cycles into account and averaging the periods between each.