produced indicates the presence of light-reflecting ice which may be too far away to see; a patch of snow or ice below, surrounded by open water.
Once light from the sun penetrates a cloudy sky, it is reflected back and forth between the layer of clouds and the Earth surface. Open water absorbs light much more effectively than ice or snow covered surfaces. As a result, clouds above open water remain dark, while the reflected light creates bright clouds above areas where there is ice cover. “Ice blink” describes when a bright patch of cloud occurs in a dark cloudy sky.
When other means are not available, people in the polar seas may use ice blink to get an approximate idea of ice conditions at a distance.