3 April 2012 Icebergs and Sea Ice Formation

Speed 0.1 knots
Course 229°
Location Inner Larsen A (-64.70645167, -59.595165)
Depth 603 meters

I've been reading the first book in the Game of Thrones series while I've been on the NBP and one of the family's motto is "Winter is coming." That seems to be a theme on the ship as well since the days have been getting colder and colder. Today we're at -1°F and if I stand in the wind, it feels like -38°F. It's cold, but amazing things happen when it gets cold enough. For starters, sea ice starts to form!

IcebergsA floating body of ice that has broken away from a glacier.

One of the most noticeable things about being in Antarctica is that as soon as we were close to the peninsula, there was ice floating all around the boat. These are icebergs that have broken off from glaciers and ice shelves. There are three main classes of icebergs: growlers, small bits of ice that the boat can hit and go over; bergy-bits, chunks of ice about the size of a Volkwagon bug up to the size of a small house; and icebergs, large pieces of ice that are bigger than a one-story house. Small growlers just make strange noises as they go under the boat, but anything that is a bergy-bit or bigger can cause serious damage to a ship.

These icebergs can float for miles. Eventually, they will melt and become part of the sea once the sun has warmed them.

One of the most important things to remember about icebergs is that only the very top of the iceberg sticks out above the water. Over 75% of the iceberg is underwater. In the picture below, the bright blue color is the part of the iceberg that is submerged below the surface.

Sea Ice

Pancake ice is formed from the saltwater in the sea itself. The ice itself is made of freshwater because the salts are left in the sea as the water freezes. The ice forms round, oblong shapes that resemble pancakes and are usually about a foot across. The pancake ice usually has a ridge around the outer edge.

As it gets colder, more pancake ice forms and eventually the individually pancakes freeze into sheets of ice. This comprises most of the ice we travel through daily. The ice can get really thick, but most of the ice we're traveling through is less than a few feet deep.

Can you tell the difference? Is this an iceberg or sea ice?

It's definitely an iceberg that came from glaciers because it's way too tall to be sea ice.