Source Rage of Elements pg. 15
The primary magical actions kineticists use are called impulses. You can use an impulse only if your kinetic aura is active and channeling that element, and only if you have a hand free to shape the elemental flow. The impulse trait means the action has the concentrate trait unless another ability changes this. If an impulse allows you to choose an element, you can choose any element you're channeling, and the impulse gains that element's trait.