Snowfall

Enchantment, 2U (3)
Cumulative upkeep {U} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Whenever an Island is tapped for mana, its controller may add {U} to his or her mana pool (in addition to the mana the land produces). If that Island is snow, its controller may add {U}{U} to his or her mana pool instead. Spend this mana only to pay cumulative upkeep costs.¹
Illus. Phil Foglio

Gatherer Card Rulings [Nov 2009]

• 8/1/2008: This mana is in addition to any mana the Island itself produces, and is blue regardless of what type of mana the Island produces.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard, MTGO Classic
Printings (1/6)	Ice Age (Common)