This is the 2907th most frequent Chinese word.
格外
"格外" means "especially" or "exceptionally."
In this sentence, '格外' means 'exceptionally' or 'especially', emphasizing the higher degree of happiness compared to usual.
他今天格外开心。
He is extra happy today.
Here, '格外' indicates a state being much more noticeable or intense, emphasizing the coldness of winter mornings.
寒冬的早晨格外寒冷。
Winter mornings are especially cold.
The term '格外' in this context describes the calmness as particularly heightened compared to standard scenarios due to the influence of the environment.