形容开心的氛围怎么说英语

To describe a happy atmosphere in English, you could use words and phrases like:

Cheerful
Joyful
Festive
Lighthearted
Lively
Upbeat
Energetic
Exuberant
Blissful
Jubilant

For example, you could say "The room was filled with a cheerful atmosphere as everyone laughed and joked together." or "The party had a festive atmosphere, with music and decorations all around."