There are a couple of interesting angles to the field where the Eagles will play the Cardinals in Phoenix Sunday in the NFC Championship Game.

And I mean that literally.

The University of Phoenix Stadium sports a retractable field. They literally roll the field up and move it outside in the sun all week. Then on game day they roll it back inside the stadium.

The idea is that the Bermuda turf needs as much sunshine as possible. That’s why it stays outside all week in the Valley of the Sun.

Of course, the field is not the only thing that’s retractable at the stadium. So is the roof. Which poses an interesting question.

One of the lures of Phoenix at this time of year (yes, there are reasons to go there besides a football game), is its glorious weather. Especially at this time of year. Yesterday the high in Phoenix was 74 under glorious sunshine. The high here is not expected to get out of the 20s.

So you would think that come Sunday afternoon the roof would be open to let in some of that lovely sunshine, right? I’m thinking not.

I am guessing that the call on the roof belongs to the team, not the NFL. And if that’s the case, I would think the Cardinals would keep the roof closed. Just as in Minnesota, the sound inside domed stadiums can be a serious factor for opposing teams.

Look for the Arizona fans to raise the roof on Sunday. Just don’t look for the Cardinals to open it.