https://www.weather.gov/media/bis/Weather_Spotter_Field_Guide.pdf
https://www.weather.gov/media/surface/SFCTraining.pdf
https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/research/library-and-archive/library/publications/weather--climate-guides/cloud_types_for_observers_rev_2014.pdf