Cloud cover Cloud cover Cloud cover (also known as cloudiness, cloudage, or cloud amount) refers to the fraction of the sky obscured by clouds when observed from a particular location. Okta is the usual unit of 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. The global cloud cover averages around 0.68 when analyzing clouds with optical depth larger than 0.1. This value is lower (0.56) when considering clouds with an optical depth larger than 2, and higher when
Ancient Roman units of measurement Ancient Roman units of measurement The ancient Roman units of measurement were largely built on the Hellenic system, which in turn was built upon Egyptian and Mesopotamian influences. The Roman units were comparatively consistent and well documented. The basic unit of Roman linear measurement was the "pes" or Roman foot (plural: "pedes"). Investigation of its relation to the English foot goes back at least to 1647, when John Greaves published his "Discourse on the Romane foot". Greaves visited Rome in 1639, and measured, among other things, the foot measure on the tomb of Titus Statilius Aper, that on the statue