Portland’s Channel 8 Purple Damage Control Piece By People Person Weatherman Matt Zaffino

Video Transcript:

My social media fees lit up people saying, hey, what is the deal with this? These big circles in the sky, one person calling them Contrill Donuts, another person and I love this saying the sky is just the canvas for the airplanes, right? Alright, yeah, it's pretty good. This picture by Edmund Dante showing the circles here and you can see the pattern like that. Another picture for you, this one from up in the Scarpus area, John Anderson sending this in. And again, you can see the loops because you know the planes are in a holding pattern, they don't want to go too far away because then they just have to come back. So they do the circular pattern. So what are the physics behind this? Well, here's the deal. When you get these circles in the sky, first of all, as we said, there was fog at sea tack and put the planes in a holding pattern. Visibility at sea tack several times this morning was down to a quarter of a mile. They won't land planes if they can't see the runway. So that's what's going on with that. And why here? Why were they not way up over Seattle? Well, because poor land is the backup landing site for Seattle and for sea tack. So if any of those planes for whatever reason had to land, they needed to be near an airport. So they were circling closer to Portland. So that's why we had them and they weren't up around Seattle. And then why did they last so long? And this we see all the time. If there's high humidity at flight level where those controls are being formed, well, then they disperse much more slowly. It's like having a cloud in a very humid environment. It just doesn't go anywhere very fast because the difference in vapor pressure is really, really low. That's the technical reason. To put it another way, if the air loft at flight level is super dry, then those controls, which are just steam, they dissipate like that. And you'll see that if you look up on a dry day when it's super clear, especially in the fall and winter when we get a lot of really dry air up a loft at flight level, you might see a little tiny control behind a plane and then dissipate really quickly or no control at all. So again, that was the science behind the controls today.