The A.B. looks good, isn't it kind of thick though? They always look light and feathery, these look thick at the bottom. These also go up perfectly straight, and the real ones tend to go up at an angle between 20-30 degrees. Just somethings I noticed.
The glacier-like look of the terrain fits perfectly!, the aurora's aren't too bad either, perhaps some lighting influence from them on the ground making the ground a bit greener would look more natural though