I'd like to learn more about why the wind is so much more favorable at dawn. It is clear that is the best time for the surf, but I am trying to learn to balance that with the favorable tides. Any ideas on how best to understand this? Thanks!
Last edited by jaabarlow; Apr 23, 2012 at 06:13 PM.
Well, Jack, if you hadn't become a lifeguard, you would have remained in synch with the ocean (Big Wednesday allusion) and would already know the answer.
Generally winds are calmer at dawn and it usually has to do with pressure gradient. Land heats and cools roughly 5x faster than water. The same sunshine beats down on the land and the water, but the land reacts to it more quickly. When the water is significantly cooler than the land (ie, the land has warmed up significantly), the air pressure above it is higher. the air (wind) moves from high pressure (over water) to lower pressure (over land). this onshore push turns the waves into poo. This phenomenon usually kicks in on days I plan to work in the morning and knock off early to go surfing in the afternoon.
On days, where there is little macroscale (large scale) atmospheric system influence in a region, microscale processes such as the land/sea breeze phenomenon come into play. The land/sea breezes occur from temperature gradients between the ocean and land, especially right along the coast line.
Dawn, can often be the coolest time of day on land. So, if at this time, the land is much cooler than the ocean, the difference in temperatures, creates an atmsopheric flow (pressure gradient) from the land to the ocean. This is when we have calm or offshore winds in the morning - land breezes.
Then, during the day, when the land heats up, and becomes warmer than the ocean, the opposite occurs. A pressure gradient sets up that creates a wind flow from the ocean to the land - sea breezes.
Today, for example, would not be a good example for the east coast, since we had a major frontal system move off the coast. These macroscale systems general have much more influence over the local winds then the small scale land/sea breezes.
As stated by Mikey, the land heats/cools much faster then the water, which allows for such temperature gradients.
On a large scale scope, temperature gradients are responsible for all weather systems. It is the differential heating of the sun on the earth that drives all atmospheric flow or pressure gradients.
Last edited by Swellinfo; Apr 23, 2012 at 08:02 PM.
Diagrams - awesome! Thanks and @ Mikey - now I have to watch Big Wednesday! I know I am not the only one always checking and trying to fit in a session, balancing with work and other responsibilities. And I have a right brain, so I like to understand things.
Check out the link below. If you need help learning the forecasting side of things, it will certainly help you get out there a lot more when it's the best conditions. I wrote this up last year and it's helped quite a few of our friends: http://www.heatedwetsuits.com/reading-swell-charts/
no wind is the best wind. Some of my best sessions have been in light side shore conditions that appear red or blue on swellinfo. You never know until you check the cam, or even better, look at it with your own two.. That is all.