Pommes de l'air are fruits as opposed to vegetables like pommes de terre (potatoes). Other famous pommes are la pomme d'Adam, la pomme de Newton, la pomme de Guillaume Tell, la pomme d'amour (tomato), la pomme de pin (pine cone), la pomme de douche (shower head), and then, last but not least, ma pomme (my face).
I'm not really talking about all those others here.
There are almost as many kinds of pommes as there are pommes in our back yard right now — even though a lot of them blew down in a wind storm a few weeks ago, and even though Walt has raked up and picked up thousands of them over the past few months.
And that's without even mentioning Granny Smith, Golden Delicious, Fuji, Reinette, or Gala. Pomme à cidre (cider apples). Pomme à couteau (eating apples). Pomme à cuire (cooking apples). French Wikipedia article lists a hundred or more apple varieties, including probably 25 different kinds of reinettes. And that's just for France.