Cloud cover is calculated by visually estimating the fraction of the sky obscured by clouds. In meteorology, this is measured in oktas, which represent eighths of the sky.
Here's a breakdown of how to determine cloud cover using oktas:
Understanding Oktas
- Visual Division: Imagine the entire sky divided into eight equal sections, like slices of a pie.
- Cloud Aggregation: Picture all the visible clouds condensed into these eight sections.
- Oktas Determination: Count how many of these imaginary sections are filled with cloud. This number is the cloud cover in oktas.
Calculating Cloud Cover in Oktas:
| Oktas | Sky Coverage | Description |
|---|---|---|
| 0 | 0/8 | Clear sky. No clouds present. |
| 1 | 1/8 | Very little cloud cover. |
| 2 | 2/8 | Some clouds are present, covering about a quarter of the sky. |
| 3 | 3/8 | Significant cloud cover, but less than half the sky. |
| 4 | 4/8 | Half of the sky is covered by clouds. |
| 5 | 5/8 | More than half of the sky is covered by clouds. |
| 6 | 6/8 | Most of the sky is covered with clouds, but some small areas of the sky are still visible. |
| 7 | 7/8 | Almost the entire sky is covered by clouds. |
| 8 | 8/8 | Completely overcast; the entire sky is obscured by cloud cover. |
| 9 | not visible | Sky completely obscured by something other than clouds (fog, snow, heavy precipitation) |
Practical Insight:
- Observation: Cloud cover is assessed through direct visual observation of the sky.
- Mental Exercise: The key is to mentally aggregate the clouds into the eight sections, making it easier to estimate the cloud cover in oktas.
In summary, calculating cloud cover involves visually estimating the fraction of the sky covered by clouds, which is then translated into oktas, where each okta represents one-eighth of the sky's coverage.
