It seems pretty obvious how ice melts, right? It gets warm, so ice changes to its liquid form — water.

However, the way that the lakes, including the Iowa Great Lakes, melt may be different than what you would think.

Usually in March — the average date for ice out on East Lake Okoboji is March 31, West Lake Okoboji is April 5 and Big Spirit Lake is April 4 — the air begins to warm and the sun’s intensity increases. That will begin to melt any remaining snow on top of the ice on the lakes and allows light to penetrate through the ice.

Lake ice acts like a greenhouse, amplifying the sun’s radiation and actually warming the water beneath the ice more than the ice is warmed itself. As the water beneath the ice warms, the ice begins to melt from the bottom. It can also melt quickly from the top if warm winds blow through the area.

Ice continues to a weakened phase with surface and internal melting. At this point, the ice usually looks gray and can become “candled.” Candled ice is eroded ice that forms into long, vertical crystals. Because of the shape, this type of ice conducts light even more. Melting water will fill in between these vertical crystals and break them apart.

As winds warm, they will continue to melt ice as well as break up any weakened and candled ice. Sometimes candles will stack up on the shore and actually make a tinkling sound.

Ice can weaken and refreeze throughout winter, but when spring arrives, the melting process can happen quickly. It might be a weekend; it might be overnight.

Ice out definitely signifies spring!

Photo of melting ice

 

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