Thursday, December 01, 2011

The Color of Water

At Sea
25 13.25 N 080 18.04 W

What color is it?  For most substances or objects we see in every day life, that's a simple question.  A few things, like the sky, do shift colors.  Few or none of them match the variety of colors that water takes.  Black, grey, white, rad, brown, tan, green, grey-green, light green, turquoise, blue, light blue, gulf stream blue, and invisibly transparent, just to name a few.  Indeed, it's hard to think of a color that water does not take on in particular circumstances.

As for the water itself, there are only two variations; opaque and transparent.  WHen water is opaque (the real word for that is turbid) it takes on the color of the suspended particles or creatures that make it opaque.  It looks muddy when a lot of mud particles are suspended.  It looks red when it is full of red algae, and so on.  When we sail past the confluence of two rivers, the two different colors of the turbid water are very evident.

In the ocean, the salt water is mostly transparent or semi transparent.  The colors we see are produced by the depth of the water, the color of the sea bottom, and the angles of the impending light.  Most of the interesting colors we see start in South Florida and go sough from there.  North of that, the water us usually a boring grey or grey-green or brown.  In our 14 north/south migrations, we have come to associate particular colors with specific places.  Polynesians are reputed to be much more skilled at that; to the point where they can navigate ocean crossings using the color (and taste) of the sea water.

As we approached Fort Lauderdale yesterday, heading south, the water became dark blue.  Not the rich rich blue of the Gulf Stream, but nevertheless very nice.  Around Key Biscayne it became green.  That's because the waters are shallow and the bottom is sandy.  Today, we're sailing the Hawk Channel in the Florida Keys. There the water will become a beautiful turquoise color that we've learned to associate with the keys.  Florida Bay, on the other side of the keys, has it's own characteristic shade of green.

The most beautiful color of water is the deep deep rich blue of the Gulf Stream.  That color is almost impossible to describe, and difficult to photograph.  When sailors talk about blue water sailing, they refer to this deep blue of very transparent, very deep waters at low latitudes.  I can tell you that when we encounter blue water, our hearts are lifted with exuberance. It is unspeakably beautiful.  Blue water is not far away from us right now.  The Hawk Channel is a body of shallow water bounded by the Keys to the North and West and by a barrier reef to the South and East.  All we need to do is to cross that barrier reef and almost instantly, we are in blue water.  We can see the thick low clouds that mark the Gulf Stream just a few miles away.  We may take a short detour out there just to see blue water once again.

In the Bahamas and in the Virgin Islands, the water is so extraordinarily transparent, that the water becomes almost invisible.  We see the bottom clearly and the objects and creatures on the bottom.  It is like looking at an aquarium.  You don't see the water so much, you see the fish, the grass, and the sand on the bottom.  It takes some getting used to. Sailing on the Bahamian banks feels like flying an airplane just above the ground.  Often, a dark patch of grass looks like a rock sticking up to the surface and it scares us that we might run into it.  

Also in the Bahamas, all the waters are shallow.  One can navigate there by the color of the water.  Blue is deepest. Dark green is deeper than light green.  Brown colored water marks shallow coral.  Yellow water marks a shallow sand bar.  Sailors make ladder steps to climb halfway up the mast to spot water colors at a distance and thus navigate tricky areas.

At night the water is usually black.  In bright moonlight however it can become silvery.  On exceptionally clear moonless nights, starlight alone can make the surface silvery. We've been told that an exceptionally beautiful sight is the Bahamas Grand Banks under a full moon.  The moonlight reflects off the sandy bottom causing an eerie glow.  We haven't see that yet.

Human eyes don't see colors well at night,so the beauty comes through variations in the gray scale.  An exception is when sea creatures cause the sea to glow in the dark (i.e. to fluoresce) then it glows green or blue-green or yellow.  It's very beautiful. You may be surprised to hear it but the most florescence we've seen is off the coast of New Jersey.

Once in the Stockholm Archipelago in Sweden, at night, I saw a bright yellow line in the water.  It started at my eye and it ended just underneath Jupiter that was just above the horizon.  The yellow line was reflected Jupitershine -- outstanding.  (There was tragedy associated with that night, remind me someday and I'll blog that story.)

White water is associated with extreme turbulence.  Think of white water rafting.  To as sailor, whitecaps mark the tops of waves. White caps just begin to appear at 15 knots of wind, which is the ideal speed for sailing. More extensive white water also marks surf and extreme danger to sailboats.  A white-out at sea marks hurricane force winds when the air is filled with suspended droplets and you can see nothing but white in all directions.

Green water is also very scary to boaters. I don't mean the turquoise green but rather the forest green color of very big waves.  If a wave is so high that it gets between your eye and the sun it appears to be green.  That's scary because that green water is likely to come crashing down on your head in a few seconds.  I've seen green water at sea, but I've seen it much more often on Lake Champlain.

What's your favorite color of water?

1 comment:

  1. Dick, this is an outstanding entry; anyone who loves light and color--and water--and who has travelled to see that water features different colors in different places, for so many different reasons will appreciate your entry especially. Thank you again. Chuck Holmes, Portland, OR


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