The air gets warm, the sun is out longer and the ice just starts to melt into water, right?

Certainly, those aspects of spring impact ice melting, but there are other factors playing significant roles.  

Once the snow mainly melts off the surface an impressive thing happens… sunlight is able to penetrate through the ice. 

Like a glass in a greenhouse, the ice actually amplify’s the suns rays and can warm the water beneath the ice.  As the water beneath the ice warms, the ice begins to melt FROM THE BOTTOM. Pretty cool, huh!

Now, obviously above average temperatures and windy days will continue to melt the ice from the top as well, but there is much more going on then appears at the surface.  

There are many phases in the melting process, each of them impressive in their own right.  Internal melting can dramatically weaken the ice sheet without significantly thinning it. Tiny pores will open up in the ice as the meltwater drains through it, making it more fragile.

Logically, thick ice weakens slowly, but it also recovers slowly.  Rain is great for clearing the snow from the top of the ice, but beyond that has less impact than you may think.  Warm wind is the primary driver of surface level melting.  

The end stage(s) are particularly fascinating.  At this point, the ice usually looks gray/black.  It looks this way because very little light is reflected.  Rotten small-grain ice, often called “candled ice”.  Candled ice is deteriorated ice that forms into long, vertical crystals.  This type of ice has even more solar conductivity.  Rapidly melted water seeps between these vertical crystals and fractures them apart.

The final stages are rather impressive.  As ice sheets and candled ice shift around lakes with the wind they collide and break-up.  Often times these floating ice sheets can do significant shoreline damage.  However, they can also create dynamic ice-scapes and create unique sounds.  People often regard the sound ice crystals make when crashing into each other as tinkling.

Just remember, while it can be fun to watch the ice disappear, safety ratings for thickness should be doubled or tripled after melting starts.   And of course, as they say, “lake ice is never really safe”… but it is pretty cool!  

If you read this far you get a special hint for guessing the ice out dates.  Usually Bald Eagle Lake goes out a handful of days prior to White Bear Lake.  🙂