Welcome, its a maybe from me. I reckon you could do with posting the height map of the terrain and then using that as a reference to index into a climate map. Then it should colour it up so that its snowy on mountains that are very high etc. Although I use linux for some things I dont generally do my terrain on linux. What have you been using so far ? Has it been bitmap editors like Gimp ? What I think you will need is a terrain editor which uses height maps. You could use wine to use some of the windows ones but here are some Windows suggestions. Wilbur, Leveller, Global Mapper, World Machine. GeoControl. You can use noise and bitmap operations. I personally like ImageMagick which is definitely available for linux as are some of the noise libraries which have been used to great effect if you can get a linux app which has linked to them. Search for LibNoise here and you will see several posts. I think with Gimp you could use the tuts here to try out some of them too.