Cloud cover

Cloud cover (also known as cloudiness, cloudage, or cloud amount) refers to the fraction of the sky obscured by clouds on average when observed from a particular location.^[2] Okta is the usual unit for measurement of the cloud cover. The cloud cover is correlated to the sunshine duration as the least cloudy locales are the sunniest ones while the cloudiest areas are the least sunny places, as clouds can block sunlight, especially at sunrise and sunset where sunlight is already limited.

The global cloud cover averages around 67-68%, though it ranges from 56% to 73% depending on the minimum optical depth considered (lower when optical depth is large, and higher when it is low, such that subvisible cirrus clouds are counted).^[3] Average cloud cover is around 72% over the oceans, with low seasonal variation, and about 55% above land, with significant seasonal variation.^[4]

^ Brun, P., Zimmermann, N.E., Hari, C., Pellissier, L., Karger, D.N. (preprint): Global climate-related predictors at kilometre resolution for the past and future. Earth Syst. Sci. Data Discuss. https://doi.org/10.5194/essd-2022-212
^ Huschke, Ralph E. (1970) [1959]. "Cloud cover". Glossary of Meteorology (2nd ed.). Boston: American Meteorological Society. Retrieved 2013-08-24.
^ Stubenrauch, C. J.; Rossow, W. B.; Kinne, S.; Ackerman, S.; Cesana, G.; Chepfer, H; Di Girolamo, L.; Getzewich, B.; Guignard, A.; Heidinger, A.; Maddux, B. C.; Menzel, W.P; Minnis, P.; Pearl, C.; Platnick, S.; Poulsen, C.; Reidi, J.; Sun-Mack, S; Walther, A.; Winker, D.; Zeng, S.; Zhao, G. (2013). "Assessment of global cloud datasets from satellites: Project and Database initiated by GEWEX Radiation Panel" (PDF). Bulletin of the American Meteorological Society. 94 (7): 1031–1049. Bibcode:2013BAMS...94.1031S. doi:10.1175/BAMS-D-12-00117.1. S2CID 12145499.
^ King, Michael D.; Platnick, Steven; Menzel, W. Paul; Ackerman, Steven A.; Hubanks, Paul A. (2013). "Spatial and Temporal Distribution of Clouds Observed by MODIS Onboard the Terra and Aqua Satellites". IEEE Transactions on Geoscience and Remote Sensing. 51 (7). Institute of Electrical and Electronics Engineers (IEEE): 3826–3852. Bibcode:2013ITGRS..51.3826K. doi:10.1109/tgrs.2012.2227333. hdl:2060/20120010368. ISSN 0196-2892.

[1] Brun, P., Zimmermann, N.E., Hari, C., Pellissier, L., Karger, D.N. (preprint): Global climate-related predictors at kilometre resolution for the past and future. Earth Syst. Sci. Data Discuss. https://doi.org/10.5194/essd-2022-212

[2] Huschke, Ralph E. (1970) [1959]. "Cloud cover". Glossary of Meteorology (2nd ed.). Boston: American Meteorological Society. Retrieved 2013-08-24.

[2013stubenrauch-3] Stubenrauch, C. J.; Rossow, W. B.; Kinne, S.; Ackerman, S.; Cesana, G.; Chepfer, H; Di Girolamo, L.; Getzewich, B.; Guignard, A.; Heidinger, A.; Maddux, B. C.; Menzel, W.P; Minnis, P.; Pearl, C.; Platnick, S.; Poulsen, C.; Reidi, J.; Sun-Mack, S; Walther, A.; Winker, D.; Zeng, S.; Zhao, G. (2013). "Assessment of global cloud datasets from satellites: Project and Database initiated by GEWEX Radiation Panel" (PDF). Bulletin of the American Meteorological Society. 94 (7): 1031–1049. Bibcode:2013BAMS...94.1031S. doi:10.1175/BAMS-D-12-00117.1. S2CID 12145499.

[King_Platnick_Menzel_Ackerman_2013_pp._3826–3852-4] King, Michael D.; Platnick, Steven; Menzel, W. Paul; Ackerman, Steven A.; Hubanks, Paul A. (2013). "Spatial and Temporal Distribution of Clouds Observed by MODIS Onboard the Terra and Aqua Satellites". IEEE Transactions on Geoscience and Remote Sensing. 51 (7). Institute of Electrical and Electronics Engineers (IEEE): 3826–3852. Bibcode:2013ITGRS..51.3826K. doi:10.1109/tgrs.2012.2227333. hdl:2060/20120010368. ISSN 0196-2892.

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