Natural Selection Nature Photography
By Mark J. Thomas
Blue Iceberg Story
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Let me begin by saying that this is a real iceberg. It was not photographed through a blue filter. It has not been enhanced in any way!!! All the features, shapes, colors and penguins are real. Each shot of this magnificent iceberg that I display is a unique shot, photographed with a different lens from a different angle. None of these shots are "cropped" images from larger shots. An iceberg like this is extremely rare! We found this iceberg totally by accident. It is certainly not something that you would be able to locate intentionally, though many have tried. I was on board a large Russian icebreaker on a trip to the Emperor Penguin colonies on the sea ice of the Weddell Sea, Antarctica. Part of the voyage took the ship to islands in the Scotia Sea, just north of the Antarctic circle. Icebergs were a common site while crossing the several hundred miles of open ocean on our way to these islands. Most appeared as bright white dots on the horizon. They were often visible from eight or more miles away. Then, "out of the blue", a dark dot appeared on the horizon. The captain was asked to take the ship in that direction. Although it was several miles out of our way, he obliged us. Many of us knew that old glacial ice appeared dark instead of white. But none of us was prepared for what we were about to see.

As the ship got closer and closer to the iceberg, it just got better and better. We approached the iceberg from the side with a beautifully carved archway. It was early afternoon and the sky was overcast. Most everyone was in the dining room enjoying their lunch. My table was by a window that overlooked the bow so I could see this magnificent iceberg as we approached. When it was still several miles away, I excused myself from the table and went to my cabin to grabbed my cameras and plenty of film. I had a feeling that this was going to be a great opportunity.

After grabbing my gear, I first went up to the bridge, some 90 feet above the ocean's surface. As we closed in on the iceberg I quickly realized that a lower vantage point might offer better angles. I grabbed my gear and headed down the stairs to the open deck, only 30 feet above the ocean. This location was perfect.  

We arrived at the iceberg to see a beautiful blue, wave-carved archway. The captain brought the ship very close. He turned the ship to starboard (right) and began to circle the iceberg. As we progressed, it just got better and better. As the ice archway disappeared behind us, beautifully carved ice sculptures emerged in front of us. Then, just when you thought it couldn't get any better, a small colony of Chinstrap penguins came into view to make it perfect.

It was so magnificent that it was almost overwhelming. I photographed the iceberg using several different lenses ranging from a 28mm wide angle to a 400mm telephoto. Each different lens offered a unique, but equally magnificent composition of the iceberg. This is one of the few situations where handholding the camera is better than using a tripod. Through the pitching and rolling of 20 foot swells, the human body automatically compensates in order to maintain balance. A tripod used under these circumstances would be useless. 

Without warning, the ship began to move away from the iceberg. We had only gone around it one time. Unfortunately, it was necessary for us to get back on course to get to our destination before nightfall. The entire experience lasted only about 20 minutes. But the memory will last forever. The area where we found this iceberg is not heavily traveled. This iceberg had never been seen before or since. The only people in the world to ever see it were the people on our ship. And it was an experience that none of us will ever forget.

This was not only a once-in-a-lifetime opportunity, it was a once-in-several-lifetimes opportunity. Even the scientists on board the ship were in awe of this iceberg. None had ever seen anything like it.

Why is this iceberg blue?

The short answer: This ice has been under extreme pressure from deep within a glacier for hundreds of thousands, if not millions of years. The interesting shapes are caused from wave action below and wind erosion above, where the waves cannot reach. When viewing one of the wider angle shots of this iceberg, it is easy to see where the high point of the wave action is (where the iceberg is no longer smooth).

The more detailed answer: To understand why this iceberg is blue, it might be helpful to learn a little bit about where icebergs come from and why most appear to be white. 

Most icebergs come from glaciers, which are huge, slowly moving fields of ice and snow. They are formed through the continual accumulation of  falling snow. Glaciers are influenced by gravity in two ways. Gravity causes the glacier to move in a downhill direction and it is also responsible for the compression of the snow that is deeper inside the glacier. If a glacier is near a coastal area, gravity usually causes it to move in the direction of the sea. Where the glacier meets the sea, huge chunks of ice continually break off from the face of the glacier in a process known as "calving." This is where icebergs are born. Once adrift, icebergs are at the mercy of the ocean currents and the winds.

The vast majority of icebergs familiar to most people appear as huge chunks of white ice. So why is this one blue? Remember, icebergs come from glaciers and glaciers are formed as a result of snowfall. As water freezes into snow, it becomes crystallized. A close examination of a snowflake reveals a many-faceted crystal, not unlike a cut diamond. These facets, or surfaces are capable of reflecting light. Snow appears white for this very reason. As snow accumulates, the structure of snowflakes trap a great deal of air. This is easily seen if you fill a glass to the top with snow, then bring it inside and allow it to melt. You quickly notice that most of what you thought was frozen water, was actually air. Because snow contains a lot of trapped air, light hitting it is able to reflect off the many internal surfaces and we see this as white.

So why do most icebergs look white but this one is brilliant blue?

Now that we know a little bit about why snow looks white, we can tackle this question. Most icebergs look white for the exact same reason that snow looks white, and for a very good reason. Icebergs are made from snow. Icebergs that come from relatively shallow or young glaciers have not undergone very much compression. Therefore, there is still a great deal of air trapped within them and they reflect back much of the light that hits them as white light.

The blue color occurs mostly in very old ice from a very deep glacier and is the result hundreds or even thousands of years of compression and ongoing thawing and refreezing of the ice. Over time, these processes release much of the air that was originally trapped by the falling snow. As this happens, the reflective surfaces of our "snowflakes" disappear. The ability to reflect light exists only when there is air between the surfaces of  the ice crystals. This very, very old, and very, very dense ice is no longer capable of reflecting light. So it no longer appears white.

That explains why it is not white, but that still doesn't explain why it looks blue?

To understand this phenomenon, simply look into the deep end of a swimming pool. Doesn't the water look blue? But if you fill a glass with this same pool water, it isn't blue at all. It's clear. What gives?

First, daylight or "white light," is not actually white at all. If you have ever seen a rainbow then you know this to be true. Light that is visible to us is actually a combination of many different wavelengths of light. Each different wavelength has a different amount of energy associated with it. If light is refracted through a prism, such as raindrops, all the colors of our visible spectrum can be seen (a rainbow). These colors always appear in the same order,
     RED
ORANGE YELLOW GREEN BLUE INDIGO VIOLET  
(ROY G BIV) in direct relation to the energy associated with each wavelength. The red end of the spectrum contains lower energy wavelengths while the blue end contains higher energy wavelengths.

As light travels through water, which is much denser than air, the weaker wavelengths of light, from the red end of the spectrum, quickly filter out while those from the blue end penetrate the deepest. This phenomenon is very familiar to SCUBA divers. At the surface, all the colors are visible. But as the diver goes deeper, the colors start to disappear. First red disappears, then orange, then yellow, right down the spectrum. Finally, at the limit of most divers, everything appears as some shade of blue. The water above the diver has filtered out most of the sunlight. Eventually, if one goes deep enough into the ocean, even the blues disappear and you are left in total blackness.

A blue iceberg is blue for this exact same reason. Since this ice has been under enormous pressure for eons, most of the air, and therefore, most of the reflective surfaces within this iceberg have been eliminated. Light hitting this iceberg no longer "bounces" off of it. Instead, it is absorbed into it. The weaker wavelengths of light are quickly filtered out. The blue wavelength, however, has enough energy to penetrate deep enough to either find some internal surface to reflect back from or penetrate all the way through this dense iceberg. Thus giving it its blue color.

It may appear that this iceberg is emitting light. This is definitely not the case. Emitted light is produced light. Like that from a light bulb, or a firefly's abdomen. The blue you see with this iceberg is not being produced by the iceberg. It is actually being produced by the sun as daylight. This iceberg is simply capturing the sun's emitted light and only allowing the high-energy blue wavelengths to escape.

 


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