Biome algorithm

(approximation of https://commons.wikimedia.org/wiki/File:Climate_influence_on_terrestrial_biome.svg)

t = temperature :: degC
p = precipitation :: cm/year

temperature < 0 => Tundra
temperature < 8
  p < 30 => Cold desert
  else               => Boreal forest
temperature < 20
  p < 30 + (t - 8) * 20 / 12  => Cold desert
  p < 50 + (tt - 8) * 70 / 12) => Woodland/shrubland
  p < 180 + (t - 8) * 60 / 12 => Temperate forest
  else                        => Temperate rainforest
else
  p < 50 + (t - 20) * 50 / 10 => Subtropical desert
  p < 240 + (t - 20) * 40 / 10 => Savanna
  else                => Tropical rainforest