| Answer | Crossword Clue |
|---|---|
| nightglow | an airglow seen during the night |
| nightglows | NIGHTGLOW, an airglow seen during the night |
| dayglow | airglow seen during the day |
| dayglows | airglow seen during the day |
| dayglows | DAYGLOW, airglow seen during the day |
| blackouts | A period when all lights must be turned out or covered to prevent them being seen by the enemy during an air raid |
| blackout | A period when all lights must be turned out or covered to prevent them being seen by the enemy during an air raid |
