Why is some of the ice whitish/light grey, while some is dark grey/nearly black? Different ice densities or surface characteristics
I am a learner in that respect myself but what I know so far is that these radar images are basically showing gradients in terrain, you see one side of a mountain as a bright area, the other as a dark area. Which side is bright and which dark depends on orientation of the satellite, the attached images were taken in different orientation. It looks like the mountains are illuminated from the side but of course the "illumination" is produced by the satellite radar.
It doesn't just show largescale sloping gradients it also shows roughness. It picks out crevassing on glaciers and cities in light shades because there are different echoes from the top and bottom of buildings for example close together.
On smaller scales broken up bits of ice also shows up brighter than flat expanses of ice. But old multiyear ice also has a bumpier surface than smoother one year ice. Then there is the question of what surface does the radar "see". The frequencies which it uses are AFAIK reflected differently by snow and ice and water. I think this is what gives those bands on the ice cap seen in the bottom left of the images. Thick snow and firn seems to always appear bright.
An important difference between the 3107 and 0108 images is that the water surface (identifiable from the visible terra image) is also bright in some places in the 3107 image. Rough water surface, waves also give a "bright" response, depending on the orientation of the satellite.
Despite the different times these images were taken there are recogniseable ice floes in all three. How different they can appear shows how much background information is needed to interpret these reliably. Sometimes it is easy to make an educated guess, sometimes not so much. Best I can do at the moment is look carefully at many images and detect patterns.
A good place for compareable visible and radar images is
http://ocean.dmi.dk/arctic/kane.uk.phpsorry I haven't taken the time to size and crop the images to match, I guess as a photographer you'll see that anyway, Jenny