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
Albedo One Fiction" 2006. "Albedo One" was voted 8th in the Nominations for the Hugo Award under the "Best Semiprozine" category for 2006. Although only the top five in the list are deemed to have earned a Nomination for the Hugo Award under this category, the event is notable as being the first time "Albedo One" has had a presence on the nominations list (and the first time an Irish genre magazine has had a presence). The event is also notable in that "Albedo One" was placed ahead of other well-known magazines such as "Lady Churchill's Rosebud Wristlet", "Postscripts" and "Apex Digest".