Air characters use the air, lightning, and more to try to save the day.
Sonic Boom is currently the only widely available Air character available. Whirlwind is a Target exclusive in North America, and the other two are currently unreleased.
Sonic Boom
Type: Air
How to get: Individual, 3-Pack (w/ Wrecking Ball and Stealth Elf)
Variations: None
Abilities: Sonic Roar, Egg Toss
Sonic Boom screams and hatches eggs. The scream is her primary attack, while the eggs spawn baby Sonic Booms that attack nearby enemies. They can even be powered up by her scream. I don't know what this says about Skylanders' representation of women...
Whirlwind
Type: Air
How to get: Individual, 3-Pack
Variations: None
Abilities: Rainbow of Doom, Tempest Cloud, Dragon Flight
Whirlwind is a unicorn who can emit rainbows from her horn. She can also flap her wings and blow wind at enemies. Basically, she's the closest thing to The Last Unicorn that Skylanders has.
Lightning Rod
Type: Air
How to get: Individual, 3-Pack (w/ Zook and Cynder)
Variations: None
Abilities: N/A
Lightning Rod uses the power of thunder to harm those who cross him. He kind of looks like a stylized Zeus chilling in his cloud with his beard and golden gauntlets.
Warnado
Type: Air
How to get: Individual, 3-Pack (w/ Camo and Ignitor)
Variations: Glow Warnado
Abilities: N/A
Warnado is a spiky-shelled turtle who can use the power of wind to summon tornadoes to help him fight off enemies.