Waves

JOANN SNODERLY/Kodiak Daily Mirror Waves crash against the shore at Mill Bay, earlier this month.

Recently, Kodiak has seen one big storm after another. One night not long ago, I woke up because twigs and spruce cones were thumping against my bedroom window as if knocking to be let in. I got up and looked at the trees in my back yard, which were swaying and waving their branches while the wind roared and tossed around every item that was not securely lashed down. Even the dog’s water bowl had gone sailing down the porch stairs. I silently told the trees to be strong and stand fast, while making the decision to plant some young spruce next spring, so they could grow up to replace the old ones when the day comes that they can’t hold up to such a tempest anymore.

Last week in class our topic was waves. What more appropriate subject to talk about while the wind howls around the high school tower? For two days we learned the terms and the physics behind ocean waves in the classroom.

On Friday we took the students for an unusual field trip. Normally, outdoor field trips get cancelled when the weather turns stormy. On this occasion I picked a day with a high wind forecast and told the students to come prepared with rain coats and boots; we would go walk into the storm.

At Spruce Cape the first part of the walk is forgivingly protected by kind trees that shelter the trail and break the force of the wind. I passed out little note cards to the students and gave each an assignment to look for a certain aspect of waves we discussed in the classroom.

Out on the point, we had to plant our feet and shout at each other while the wind was whipping our hair and clothes. There were big waves of all shapes to be seen: Surging, spilling, and plunging breakers. We saw interference of waves, where two waves add to each other and create a bigger wave or two waves that cancel each other out, their energy just dissipating. Around the point oncoming waves get refracted, or bent. We also tried to look for wave trains — series of waves of similar wave height and wave length that travel in groups. As we stood on the point, foam was blown off the wave tops and flew through the air like big snow flakes.

After a few minutes our coats were weakly giving in and wet and cold began to seep through. We continued on our way around the point to the beach and while hiding under some trees we determined the wave period by counting how many wave crests passed a certain point in one minute. We counted seven to eight waves per minute. Then we discussed the shape of the beach face and how the waves alter it over the course of the year.

As the first students started shaking with cold, I broke off the review of the wave lesson and headed back towards the trees. “That was FUN!” one of the boys panted as he caught up to me. Another stated, “Yeah, I never go out in weather like this, but this was awesome.”

Big waves have a way of showing off their power and energy. Watching them on a windy day, it feels like some of that energy reaches and invigorates us. However, why do we get so many storms here in winter? When high and low pressure systems build up in the Gulf of Alaska, the air travels from the high to the low pressure center. This starts the wind blowing. The wind disturbs the surface of the ocean and starts to displace water, first creating small ripples, which build into chop and then to waves of increasing size. The longer the distance over which the wind blows, the higher the waves.

What travels, however is not the water, but only the energy of these waves. The energy can set more water into action and create more waves. In this way, you can get big waves in places where you didn’t have strong winds.

In class we watched a film about a surfer’s paradise in California, known for its huge waves. The place is called Mavericks, hailed as one of the most dangerous surf turfs in the world. The birthplace of Mavericks’ large waves is actually the same as that of the waves at Spruce Cape; the Gulf of Alaska. Because of the long travel distance of the waves, they turn into an ocean swell with a very long wavelength. That and the specific topography of the shore at Maverick tranforms them into fast-building huge waves, so powerful that they register on the San Francisco earthquake watch seismographs. If you are among those few surfers who enjoy their sport at Mill Bay Beach or out at Spruce Cape, here is your claim to fame: You have surfed waves that formed in the same place as the Mavericks.

As invigorating as our field trip was, by the time I was home that night warming up in front of the fire place, I felt rather tired. The amazing power of the ocean can get a bit overpowering at times.

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