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The cloud base height, the cloud layer height and the amount of clouds in different layers are computed by the Vaisala CL51 algorithm based on raw backscatter data (time resolution: 6 s and vertical resolution: 10 m).

The sky condition algorithm is calculated every five minutes based on data collected during the last 30 minutes. The last 10 minutes are double-weighted to make the algorithm more responsive to variations in cloudiness. The algorithm uses cloud base height and timing information to find cloud base height close each other. These cloud base height are combined into clusters and a height value is calculated for each cluster. This height gives the base height of a cloud layer represented by the cluster. The algorithm reports layers by combining clusters whose heights are close to each other and then selecting clusters that cover the greatest amount of sky.