<P> A polar ice cap or polar cap is a high - latitude region of a planet, dwarf planet, or natural satellite that is covered in ice . </P> <P> There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land; only that it must be a body of solid phase matter in the polar region . This causes the term "polar ice cap" to be something of a misnomer, as the term ice cap itself is applied more narrowly to bodies that are over land, and cover less than 50,000 km2: larger bodies are referred to as ice sheets . </P> <P> The composition of the ice will vary . For example, Earth's polar caps are mainly water ice, whereas Mars's polar ice caps are a mixture of solid carbon dioxide and water ice . </P> <P> Polar ice caps form because high - latitude regions receive less energy in the form of solar radiation from the Sun than equatorial regions, resulting in lower surface temperatures . </P>

When does the ice cap in the polar regions melt