International Cloud Atlas: http://library.wmo.int/pmb_ged/wmo_407_en-v2.pdf
Cloudspotting and Weather Prediction:
http://www.theguardian.com/lifeandstyle/2014/apr/12/cloud-spotting-beginners-guide-predicting-weather
http://www.theguardian.com/lifeandstyle/2014/apr/12/cloud-spotting-beginners-guide-predicting-weather