0 0 None
1 1 Rime ice in cloud
2 2 Clear ice in cloud
3 3 Combination rime and clear ice in cloud
4 4 Rime ice in precipitation
5 5 Clear ice in precipitation
6 6 Combination rime and clear ine in precipitation
7 7 Frost (icing in clear air)
8 8 Non-persistatnt contrails (less than 1/4 nmi (nautical mile?) long)
9 9 Persistent contrails
15 15 Missing value
