Writing a cloud cover, in the context of meteorology, primarily involves expressing the amount of the sky obscured by clouds, typically as a percentage. Here's how to effectively describe cloud cover:
Understanding Cloud Cover Percentage
As defined in modern meteorology, cloud cover is expressed mainly as a percentage.
- 100% Cloud Cover: This indicates a totally cloudy day, where the entire sky is covered by clouds.
- 25% Cloud Cover: This signifies a day that is more clear than cloudy, with only a quarter of the sky covered by clouds.
- 0% Cloud Cover: This represents a clear day with no visible clouds at all.
Methods of Describing Cloud Cover
Here's a breakdown of how you can write a cloud cover description:
Numerical Percentage
The most precise method is to provide the cloud cover as a numerical percentage.
- Example: "The cloud cover is estimated to be 60%."
Descriptive Terms
While percentage is precise, descriptive terms can add context. Here's how percentages typically translate:
| Cloud Cover Percentage | Descriptive Term |
|---|---|
| 0% | Clear |
| 1-25% | Few |
| 26-50% | Scattered |
| 51-75% | Broken |
| 76-99% | Overcast |
| 100% | Totally Cloudy/Overcast |
- Example: "The sky is mostly clear with a few scattered clouds (approximately 20% cloud cover)."
- Example: "Overcast conditions prevail, with an estimated cloud cover of 80%."
Using Oktas
While less common now, cloud cover can also be described using oktas, where the sky is divided into eighths. One okta represents 1/8th of the sky covered by clouds.
- 0 oktas = 0% cloud cover (clear sky)
- 8 oktas = 100% cloud cover (overcast)
Practical Considerations
- Observation Point: Specify where the observation is taken (e.g., "Cloud cover as observed from the airport is...").
- Time of Observation: Note the time the cloud cover was assessed (e.g., "At 14:00 UTC, the cloud cover was...").
- Cloud Types (Optional): For a more detailed report, include the types of clouds present (e.g., "Broken altostratus clouds cover approximately 60% of the sky.").
