Monday, April 14, 2008

How ice melts

We hope the ice melts at some point this spring. Its certainly taking its sweet time. Next Thursday is the kayak demo on Lake Calhoun, part of Midwest Mountaineering's Outdoor Expo and the folks at Midwest are a bit concerned. Our SKOAC group will be providing safety boaters and I reassured Jerome at Midwest that I would throw in my ice fishing stool along with the kayak gear. Big plates of ice are still drifting around the Apostles although the Madeline Island Ferry has been operating for a bit over a week now. The image above is of the ice buckling near the Trek & Trail launch in Bayfield. When the wind blows the ice toward shore and it has nowhere to go it just buckle up. When the plates of ice press together out in the lake you get pressure ridges such as the one in the image below.

But I'm pretty much sick of ice. Its too thin and black to skate or fish on and it makes kayaking extremely difficult. So why and how does it melt? Normally in March the air warms and the sun gets more intense which melts the snow and allows light to penetrate the ice. The ice acts exactly like glass in a greenhouse and the water beneath the ice begins to warm and the ice starts to melt... from the bottom up! When the ice melts to about 4-12" (10-30cm) it transforms into long vertical crystals called 'candles'. These conduct light even better so the ice starts to look black because not much sunlight is being reflected. Even my dad, a notorious thin ice fisherman, would avoid black or 'honeycomb' ice as being too unsafe, even when the lunker bluegills were biting voraciously. Warming continues and meltwater fills between the crystals which start breaking up. Then the wind comes up, breaks the surface apart, and piles the crystals up on the shore. And out come the kayakers! Since I am far too scientifically ignorant to come up with the cogent and understandable description above, I need to credit Ed Swain of the Minnesota Pollution Control Agency. Heck, I didn't even take the pictures so I'll need to credit RangerMark for those. In fact if I don't get on the water soon I may need to change this to a microbrewed beer review blog, 'The Malt/Hop is the Boss'. Eight of us have $10 apiece in an 'ice out on Lake Calhoun' pool and the last date picked was tomorrow, chosen by the VOR. This means she needs to buy a round for the rest of us losers at the first Lake Calhoun paddle of the season. Here's hoping its before the demo 10 days from now.


Silbs said...

Nice post. I look forward to your follow up article, "Watching grass grow" :)

DaveO said...

Hah! That should be out around May 15th, shortly after the 'watching a bridge rust' and 'Paint: how it dries' posts.