'Warm' lines across roof

[Jameze]

Sorry for the thread but it's always intrigued me...

Why does snow / ice always melt in this pattern on my roof?

I assume it's some description of wiring in the roof which is warm? It's pretty much runs across the driver / passenger's head.

I notice it all the time and it always makes me wonder what causes it!

 

[hades-]

my bonnet does that

 

[Johnny Bravo]

There are reinforcements in those areas and the temperature is different.
You can see better on the bonnet. If you remove that noise insulator you'll notice that the pattern matches the reinforcements underneath.

 

[NHN]

That's the supports on roof & bonnet.

Edit: beaten to it lol.

 

[Jameze]

Aaah completely different to what I thought then!

Cheers, I've always wondered exactly what causes it. I can put my mind to rest now