weather fog per biome

i am looking to customise fog for specific biomes, as an example ill just use snowy plains.
this is done in vanilla 1.20.6 
I tried using a file under this directory ".minecraft\saves\world\datapacks\razvans_fog.zip\data\minecraft\worldgen\biome\snowy_plains.json"
and i copied the default snowy_plains.json from the version folder and added this under effects 
    ...
    "fog_density": {
      "weather": {
        "type": "linear",
        "start": 0.0,
        "end": 0.1
      }}```
this doesnt work basically so im wondering how to go about this