User blog comment:Lightning the Skrill/Snow Wraith Frost?/@comment-26219548-20150710080520

I don't think that Snow Wraiths summon storms, instead they wait for a storm before they strike.

Perhaps the Snow Wraith uses a similar mechanism as the Bewilderbeast. It takes in water, freezes it in puches and then ejects it. I'm not very sure how this whole thing works but perhaps, it should be similar to that of the Bewilderbeast.

Also, I believe that these 'pouches' that they generate heat from have a totally different temperature from the rest of its body. Or perhaps a chemical reaction makes it lose heat. Take for example, the Bombardier Beetle (A real insect) has two organs that store two different chemicals. They are then channeled into another organ and when both react together, they become hot. They then eject this hot chemicals. In the Snow Wraith, they could have a organs that are cold, unlike the Bombardier beetle's which is hot, and as such, they can generate cold in certain organs only.

Perhaps, the Snow Wraith burns food slowly but conserves a lot of energy. They should be less active during the times without storms and they can conserve energy better this way. Let's not forget that they are cold-blooded and cannot regulate their body temperature. Most cold-blooded creatures consume a lot to get energy in case they end up in a cold environment and this may be so for the Snow Wraith and other 'ice' dragons.

These are just all my theories and speculations. There is too little information given on dragon anatomy and HTTYD has many more mysteries! Anyway, hope this makes some sense and perhaps, spark of a more logical theory :P