meteorology
Why does it seem like the west coasts of the seven continents have bigger and more consistent surf than the east coasts?
asked by Mike Kassak
Answer
Surfline's very own tag team of Adam Wright and Marcus Sanders take a stab at it:
Well, Mike, you're pretty right on: west coasts do get better surf than east coasts, the world over. By "better" we mean west coasts are given to long-interval groomed groundswells over reefs, rather than scrappy, short-interval windswells.
And no, it's not just luck. It's actually pretty simple. In order to get serious groundswell -- that is, a swell with an interval of more than say, 14 seconds between wave crests, which can translate to corduroy-like lines and pinwheeling spokes along a pointbreaks such as Rincon -- you need a large area of water for wind to blow across for an extended period of time. This is called fetch, and along with wind duration and wind speed, it's one Sean Collins' three Golden Rules of surf creation:
"Wave generation requires three variables: wind velocity, wind duration and wind fetch. The harder the wind blows, the longer the time it blows and the greater the distance it blows, the bigger the waves. Limitation of any one of these variables will severely restrict the development of wave heights and the transfer of energy into the water."
OK, so you need a bunch of water for wind to blow across. Big deal. How can France see 12-foot grinding Guethary -- with 10 wave sets, evenly spaced out -- while New Jersey is shoulder-high and breaking all over the place? Same ocean, right? Well, yeah, but here's the kicker: due to the fact that the earth is spinning (duh), almost every single significant frontal storm, in both hemispheres, tracks from west to east.
