Cloud Observations - Ground-based |
Ground-Based
Description of Sky Conditions
Description | ASOS (NWS) | Human | Meaning |
Clear (CLR or SKC) | 0to 5% | 0 | No Clouds |
Few | >5 to <25% | 0 to 2/8 | Few clouds visible |
Scattered (SCT) | > 25 to <50% | 3/8 to 4/8 | Partly cloudy |
Broken (BKN) | > 50 to <87% | 5/8 to 7/8 | Mostly cloudy |
Overcast (OVC) | > 87 to 100% | 8/8 | Sky is covered by clouds |
Sky obscured | NA | NA | Sky is hidden by surface-based
phenomena, such as fog, blowing snow, smoke and so forth, rather than by cloud cover |
table adopted from Meteorology Today by C. Donald Ahrens © 1994 West Publishing Company
ASOS - Automated Surface Observing System - uses a ceilometer to automatically measure cloud heights