Albedo their reflectivities. Fresh 'black' ice exhibits Fresnel reflection. Snow on top of this sea ice increases the albedo to 0.9. Cloud albedo has substantial influence over atmospheric temperatures. Different types of clouds exhibit different reflectivity, theoretically ranging in albedo from a minimum of near 0 to a maximum approaching 0.8. "On any given day, about half of Earth is covered by clouds, which reflect more sunlight than land and water. Clouds keep Earth cool by reflecting sunlight, but they can also serve as blankets to trap warmth." Albedo and climate in some areas are affected by artificial clouds, such as
Martian surface abundances) of the Martian surface. The resulting data help scientists understand the planet’s mineral composition and the nature of geological processes operating on the surface. Mars’ surface layer represents a tiny fraction of the total volume of the planet, yet plays a significant role in the planet’s geologic history. Understanding physical surface properties is also very important in determining safe landing sites for spacecraft. Like all planets, Mars reflects a portion of the light it receives from the sun. The fraction of sunlight reflected is a quantity called albedo, which ranges from 0 for a body that reflects no sunlight