0 0 None
1 1 Light turbulence
2 2 Moderate turbulence in clear air, infrequent
3 3 Moderate turbulence in clear air, frequent
4 4 Moderate turbulence in cloud, infrequent
5 5 Moderate turbulence in cloud, frequent
6 6 Severe turbulence in clear air, infrequent
7 7 Severe turbulence in clear air, frequent
8 8 Severe turbulence in cloud, infrequent
9 9 Severe turbulence in cloud, frequent
15 15 Missing value
