Satellite image of Greenland. You clearly see the ice cap covering almost entire Greenland. Only in summer the coastal areas are free of snow. Far left you can see Baffin Island. (from: NASA)
Because the snow-surface reflects most of the sunlight, the temperature is lowest near the snow and increases in upper air levels to 2 km. This is an exceptional situation because usually temperature decreases in higher air levels. The dome structure of the icecap causes cold air to flow constantly to lower areas at the edges. So, crossing the icecap you will always experience head wind until the top of the icecap and then backwind.
Above the seas around Greenland the air is less cold and thus creates a substantial difference in temperature and air-pressure between the coast and the inland. This can cause terrible storms: the feared Piteraqs.