I’ve had a handful of surf sessions this past Summer (Dec – March) that had me shivering. And not just a “this isn’t so bad” shivering, I’m talking about teeth chattering, lips turning blue, nipples hard enough to cut glass, type of shivering. As my mind wanders between waves, I can’t believe that I am surfing in this tropical paradise only 10 degrees latitude away from the equator while still freezing my huevos off!
How is it possible that the water can go from a bathlike 85 degrees Fahrenheit to a chilly 65 overnight? A more complex explanation would take us deep into the world of hydro and thermodynamics, but that is a little further than my saltwater brain is willing to go right now.
The simple answer can be explained by the phenomenon of upwelling. Imagine this: If there was no wind, our ocean layers would be heated very uniformly— warmest at the top where the most sunlight hits, and cooler as you increase depth. But once you add surface wind into the mix, our perfectly layered package starts to lose its normalization.
According to the National Oceanic and Atmospheric Administration (NOAA), when the surface wind blows strongly from land to sea, warm surface waters are pushed offshore and water is drawn from below to replace the water that has been moved away.