Questions & Answers about Ночью снег покрыл дорогу.
Why does ночью mean at night here?
Ночью is the instrumental singular form of ночь (night), and in Russian the instrumental case is often used in time expressions to mean during or at a certain time.
So:
- ночь = night
- ночью = at night / during the night
This is a fixed, very common pattern:
- утром = in the morning
- днём = during the day
- вечером = in the evening
- ночью = at night
So Ночью снег покрыл дорогу means During the night, snow covered the road or more naturally At night, snow covered the road / Overnight, snow covered the road.
Why is снег in the basic form?
Because снег is the subject of the sentence.
In Ночью снег покрыл дорогу:
- снег = snow → subject
- покрыл = covered
- дорогу = road → direct object
Subjects in Russian are normally in the nominative case, which is the dictionary form. That is why you see снег, not some changed form.
Why is дорогу not дорога?