what is okta in meteorology

In meteorology, an okta is a unit of measurement used to describe the amount of cloud cover at any given location such as a weather station. Cloud cover is the amount of clouds in the sky or the degree of cloud cover, and it is estimated in terms of how many eighths of the sky is covered by clouds. An okta is a circle divided into eight parts, each part representing how many eighths of the sky is covered by clouds. Therefore, the okta is also called “eighths”. When used in weather charts, okta measurements are shown by means of graphic symbols contained within weather circles, to which are attached further symbols indicating other measured data such as wind speed and wind direction. Oktas values are usually presented in tables, and the scale ranges from 0 to 10, with 0 representing the complete absence of cloud, and 10 representing no measurements taken at all. An okta 9 is used when the sky itself is not visible due to low-lying fog or heavy snowfall and other similar phenomena.