RE: [Paddlewise] Re: "Sneaker Waves"

Matt wrote: -
>My understanding is that a "Wave of Translation" or
>soliton is a wave that moves water from one place to
>another. The most common one we are likely to
>see clearly is the soup wave that runs up the beach 
>after a wave enters shallow enough water to destroy its
>normal orbital wave motion and break. If you watch this
>for awhile you will also see waves formed in this near
>shore zone that aren't breaking and aren't soups, but
>well up in a single smooth steep wave (often somewhat
>crossing the breaking soups). Other instances of
>Waves of translation could be the waves at the front of a
>tidal flow entering a narrowing channel that focuses the
>energy such as the Bay of Fundy, Turnigan Arm in AK, the
>mouth of the Amazon and several other river mouths abound
>the world (known as tidal bores). 


G'Day Craig, Matt and all,

Those waves seem to go by the name "Wave Of The Day" in Oz. The one wave in a thousand that is just huge compared to its neighbours. Or is that a sub set of the phenomenon? Knowing how to tell if the conditions are right for their occurrence would be handy. I met one in a cave last week, fortunately it wasn't too big and I saw it coming long before it broke.

I tend to look out for long period waves because of their size when they break and the way they wrap around headlands and close out bays so that there's often no place to easily escape them. Particularly awkward if the waves are repetitive long period waves.

Matt thanks for your description of solitons at tidal bores. It made me think about the Severn bore that runs near my parents last home. The bore is a wave that can be a meter or two high at its start and travels for many kilometres in and out of the Severn three or four times a month, due to tidal flow into the progressively diminishing width and depth of the river. 

Does the term wave of translation refer to water being moved from one place to another, or to a moving wave? If the origin of the wave is tidal as in he Severn bore then it seems reasonable to accept that it refers to water moving but if one considers it as a particular kind of interference pattern then of course its not necessary for the water to move. 

My remembrance of wave maths makes me want to think that it is the wave in the upper reaches of the bore that is the soliton and that the mouth of the Severn is just moving water in the sense that a rising tide is moving water. It leaves me wondering whether just part or all of the Severn bore can be described as a soliton?

All the best, Petero
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