| 云量 | 太阳辐射等级 | ||||
| 总云量/低云量 | 夜间 | h ≤ 15˚ | 15˚ ＜ h ≤ 35˚ | 35˚ ＜ h ≤ 65˚ | H > 65˚ |
| ≤4/≤4 | −2 | −1 | +1 | +2 | +3 |
| 5~7/≤4 | −1 | 0 | +1 | +2 | +3 |
| ≥8/≤4 | −1 | 0 | 0 | +1 | +1 |
| ≥5/5~7 | 0 | 0 | 0 | 0 | +1 |
| ≥8/≥8 | 0 | 0 | 0 | 0 | 0 |