Insolation is defined as the " the solar radiation that reaches the earth's surface." It is reflected<span> and scattered back to space through its interaction with clouds, water vapour, dust and pollen, known collectively as aerosols or it is absorbed by clouds and gaseous elements and hence heats the atmosphere. </span>
There are actually several great characteristics of the ice sheet that makes a good reflector of insulation. One of the main characteristics is that the ice and snow are both white. Other ways you put this is the ice sheet is smooth, light in color, and shiny/glassy. Any of these are acceptable answers.