A spinning world: Watching icebergs set in motion a whole new science

As their guide aboard, I have recently converted this group of wildlife nuts to watching icebergs. They are full of the vim and chatter of new converts. One of them is a short, elderly, bespectacled woman named Glenis. She sips whiskey and hot water from an orange thermos. Glenis describes her trip down to the ice as “just the ticket”.

We have been watching icebergs for a while, rugged up against the cold. The bergs around us show the signs of advanced age having been ravaged by time and the weather into all manner of tortuous shapes and sizes. Like cloud watching, berg watching lends itself to the imagination, a sort of Rorschach test for the adventurous. Among the fleet of bergs that surrounded the ship were spaceships, tankers, the Empire State Building and the ubiquitous Henry Moore sculptures.

One of the group confesses to having seen the Virgin Mary earlier in the day. Glenis gives out a snorty laugh before stopping it short with a gasp: “Oh look at that one, it looks like the face of Roald Amundsen.” It has the hooked nose and wild staring eyes of the Norwegian whose expedition was the first to reach the South Pole. It appears to be going against the drift of all the other bergs, smashing its way through the pack ice like an icebreaker.

Glenis is not the only one to see strange things while iceberg watching. In the late 1800s, another great Norwegian explorer, scientist Fridtjof Nansen, witnessed a peculiar phenomenon in the Arctic Ocean. From aboard his polar vessel Fram he saw icebergs that seemed to have a mind of their own. Instead of moving squarely down wind like a piece of driftwood they seemed to travel at an angle of 45 degrees to the right of the wind.

He thought at first it may have been some unseen current tugging at their keels, but over the course of the voyage they repeatedly displayed the same behaviour.

He spent three years trying to drift across the North Pole while frozen in the pack ice. Three years locked in the ice meant he got far too much time to observe the peculiarities of icebergs.

He mulled over this phenomenon and on his return to Norway passed his observations on to an up-and-coming oceanographer at Uppsala University in Sweden, Vagn Ekman. Ekman was a studious physicist who was fascinated by the ocean and quickly applied his immaculate mathematical mind to the problem. He was able to observe that as wind moves over the ocean it drags along the upper layers with it. It is simple friction, like blowing on a saucer of milk, but on a much larger scale. This would mean a direct flow of water down wind, but for the fact we live on a spinning planet.

The Coriolis effect means large masses of air and water are bent as they attempt to move in a straight line – to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The frictional movement of the topmost layer of water sets in motion the layer directly underneath it, which then sets in motion the next layer under that, and so on, forming something like a diminishing spiral staircase of movement in the water column. Some energy is lost in each transition, so the movement peters out at about 100m down.

This phenomena is named the Ekman spiral and the net effect is that surface water moves in a direction about 45 degrees from the wind direction. This is what caused Nansen’s icebergs to move to the right and was also the reason the Fram’s drift in pack ice across the Arctic Ocean stopped 303 nautical miles short of the North Pole. With Ekman’s yet-to-be-discovered curve gripping the Fram and his goal slipping away, Nansen and fellow explorer Hjalmar Johansen set out on skis and with dogs in a desperate but futile attempt to reach the North Pole.