Gray & White Ice

Black ice is formed from lake water. Gray and white ice, on the other hand, are formed from precipitation, primarily snow and sleet. And therein lies the difference: Gray and white ice are full of trapped air, since fallen snow is mostly air. When the snow turns to slush, the air never gets fully squeezed out, and when slush freezes into ice, that air remains trapped within it. The whiter the ice, the higher the air content, and the softer it is - until it’s as soft as snow and you can’t skate on it.
From now on I’ll refer to all of it (both white and gray) as gray ice.
Because of its high air content, gray ice is about 50% weaker than black ice. It also deteriorates in a different way when exposed to sun and warm temperatures. It’s important to know how this deterioration takes place, if you plan to skate when the air temperature is above freezing. And in our warming climate, those above-freezing winter days are going to become more and more numerous.
On cold days, black and gray ice are equally easy to skate on. But on a warm sunny day, the surface of gray ice can break down rapidly. The sun heats up the air bubbles just below the surface, and they melt the snow in between them. Lots of tiny air bubbles join to form a big bubble and their neighbors are doing the same thing. Then your skate blades start to sink into the ice instead of gliding across it. You may end up double-poling or even walking back to shore. But on the plus side, those air bubbles are reflecting much of the sun’s energy back into space, insulating the solid ice below.
Contrast this with black ice, which is transparent and allows the sun to penetrate through it. In December and January, the sun is so low in the sky that it bounces off instead of penetrating. But it’s a different story in March when the sun is high in the sky. The sun shines through the ice, heats up the water below, and rots the ice from underneath. And then the ice can collapse catastrophically.
Orange peel
Gray ice can be smooth, bumpy, or what we call ‘orange peel’. Orange peel is a consistently textured surface formed by snowflakes landing on the ice when it is wet. The melted snowflakes then refreeze on the surface, each one forming a tiny bump about half an inch in diameter, and separated from its neighbors by a similar distance. Depending on the sizes of the snowflakes, the ice texture can range from light to coarse. But thanks to the length of our Nordic blades, one blade can straddle half a dozen bumps, and though you can see the bumps, you rarely feel them.
What makes gray ice bumpy
Gray ice can become covered with bumps that are totally random in size, shape and separation. These bumps can be annoying because they break your rhythm and force you to break your stride.
Some bumps begin their life as snowdrifts that only partially melted before re-freezing. These bumps may have crusty tops which can be blade-grabbers.
Other bumps result from ‘sandwich ice’ where a layer of water has become trapped between two layers of ice. As the trapped water begins to freeze, it expands and ruptures the top layer of ice, oozing out of minute holes and spreading across the surface as it slowly freezes. Ice that was perfectly smooth the day before can be covered with bumps the next morning.

A serpentine crack in hard gray ice on Lake Winnipesaukee.