d'un air - with an air of

Hello everyone
I keep coming across the above phrase and it seems to work with adverbs.  Have a look at what I mean:

Je dois commencer à sortir plus souvent, décida-t-elle d’un air résolu.
I must start going out more, she decided resolutely.

"Non, pas vraiment,“ répondit Marie d’un air indigné.
No, not really, replied Marie indignantly.

"Yvonne," répondit-elle d’un air boudeur...’
"Yvonne," she replied glumly.

Also,
"Where do you live?" he asks.
"215 Rue des Martyrs," dit-elle d'une voix rageuse.
.... she said with a voice of rage.

"Merci," dit-il d'un ton taquin.
"Thank you," he said in a teasing tone.

"Je le savais!" dit-il d'un air méprisant.
"I knew it!" he said nastily.

Hope you find these examples helpful.
Jane xx