[What does "shimmering like adra" mean]

Vikke, appreciate your quick reply and thank you for exhausted explanation on topic.

[What does "shimmering like adra" mean]

Hey, 

 

I found Grieving Mother in Dyrford Village and fascinated by simile "shimmering like adra" during conversation, however I would like to kindly ask you if anybody know meaning of this simile?

 

Please see below image for more details about simile am talking about:

 

Thank you!