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 an 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.
See also: water sky.