No voyage from South America across the Drake Passage to Antarctica is complete without celebrating the first sighting of an iceberg. On cruise ships, a bottle of fine champagne is awarded to the first guest to inform the officer on the bridge of the sighting.
Most people travel to Antarctica aboard a cruise ship. Which is how we experienced the White Continent recently. We were aboard the Roald Amundsen, a Norwegian “excursion” ship that visited Kodiak last summer. I say “excursion” because science is emphasized with the presence of top-notch birders, geologists, marine mammal biologists, and ice experts.
Icebergs can be so brilliantly white they are impossible to look at — and photograph — without squinting. When I spotted my first iceberg, the sky was overcast and soft. But that didn’t dampen my excitement. It was a table iceberg, adorned with streaks of blue. Waves crashed against its windward face, looking as if we were sailing past the white cliffs of Dover.
Scientists were outwardly subdued, as if sighting the first iceberg is routine and benign. Not for me.
“What causes the blue color in icebergs?” I queried several biologists standing in a circle.
What followed was a group discussion about how icebergs are made of snow and glacier ice which is compressed snow.
Icebergs are white because they contain a lot of bubbles and snow particles which means all wavelengths of light are scattered before they get absorbed.
However, the fewer bubbles there are, the less chance there is of light being scattered. This results in red wavelengths being absorbed, with only blue light being scattered and escaping the iceberg. Hence we see a blue color.
What does this have to do with gardening in Kodiak?
You might be wondering what all this snow means for salmonberries, blueberries, and pests like slugs and aphids. Well, you might be tired of shoveling the white stuff from your driveway, but to plants, snow is a good thing. For the most part.
There is a saying, “A good winter with snow makes all the plants grow.”
While snow brightens dull landscapes and lifts our moods, in the garden, snow acts like a blanket. But it can also cause trouble.
Did you know that temperatures under a layer of snow is usually warmer than the outside air? All thanks to the structure of snowflakes. Inside each crystal are hundreds of tiny air pockets encased in ice. Even larger air pockets form when snowflakes heap together on the ground. The result is a fluffy, down quilt that insulates the ground. Without snow, prolonged periods of cold can spell trouble. Roots are unable to take up water which means plants can die from dehydration.
Be glad then that our snow is not blue!
THE GOOD SIDE OF SNOW
Snow’s whiteness reflects a certain amount of sunlight. But much of the light penetrates the snow. Which means plants can continue photosynthesis through the winter. And as snowflakes tumble to the ground, sulfur and nitrogen compounds cling to the crystals. Then, when the snow melts, these elements release into the soil where plants absorb them.
Snow eases freeze-thaw periods which cause water in the soil to expand and contract. Roots break, daffodil bulbs turn to mush, even launching out of the soil. A blanket of snow saves the day by softening the blows of extreme temperature swings.
Snow is also the perfect bird feeder because brown seeds stand out against a the white of snow for birds and small animal to find.
THE BAD SIDE OF SNOW
A thick layer of snow may block sunlight to the point where it prevents snow warming from below. This can delay emerging of bulbs and perennials in spring. While severe cold kills many pests, a blanket of snow can shield slugs, snails, molds, even aphids, allowing them to overwinter quite nicely in their snow condo.
Snow might be a great insulator, but too much of a good thing can break branches and trunks. In addition to clearing your driveway, try to remove snow from greenhouses and sheds. I’ve watched with dismay as a slab of snow slid down my greenhouse roof and crushed a favorite rhododendron.
The sighting of the first iceberg is always a moment to celebrate in any and all Antarctic expeditions. How did I celebrate that joyous moment?
Unfortunately, champagne never appeared. So I settled for a cup of coffee and dreams of seeing penguins, seals, albatrosses and whales. For our trip to Antarctica, that was the tip of the iceberg.
Later this spring I’ll share our experiences on the White Continent. Stay tuned.