Alignment is relationship to self and the environment. It's fluid, dynamic and ever changing. Much like the seasons...your yoga and meditation practise.
Even when standing 'still' the earth is always moving, we are always moving. A gift of our bipedal (two legged) structure is out multidimensional agility of body and mind, which keeps us alert and responsive, adaptable to change. The risk is that the instability can cause fear and rigidity in our attitudes and stance. Minds and bodies get fixed or closed when we're scared.