Airplanes Unexpectedly Modify Weather

reillymj writes "Commercial airliners have a strange ability to create rain and snow when they fly through certain clouds. Scientists have known for some time that planes can make outlandish 'hole-punch' and 'canal' features in clouds. A new study has found that these odd formations are in fact evidence that planes are seeding clouds and changing local weather patterns as they fly through. In one case, researchers noted that a plane triggered several inches of snowfall directly beneath its flight path."

Comments

Cloud Seeding

[illumastorm]

Interesting. So the effect of cloud seeding is just as likely to be caused by the planes flying through the clouds rather than the silver iodide alone?

Re:Cloud Seeding

[bunratty]

I would think anyone who understands how to design experiments would see the need for a proper control group. If you fly a plane through some clouds and dump iodide crystals, and don't fly any plane though other clouds, what caused the difference in precipitation? Was it the plane or the iodide crystals? Didn't they carry out such a proper experiment?

Re:Cloud Seeding

[sexconker]

I would think anyone who understands how to design experiments would see the need for a proper control group.

We've already seen that no one who understands how to design experiments has anything to do with the study of weather or climate.

Not surprising

[JWSmythe]

    This isn't terribly surprising. Clouds are a delicate formation of moisture that hasn't collected into dense enough masses to fall. Aircraft disturb the air, blowing that moisture around. We've known about contrails for an awful long time. I wouldn't be terribly surprised to find that particles in the exhaust give the moisture something to cling to (i.e., cloud seeding).

    Those are some nice pictures though.

I thought this was well established?

[Deagol]

The data from the near-universal grounding of US airspace the days following the 9/11/01 attacks shows pretty conclusively that air traffic has a non-trivial affect on weather patterns. Or at least that's what's I recall from the time.

Tenerife

[bigtomrodney]

It is well known locally on the Canary Islands that this happens. Almost all flights come in on Tuesdays and Saturdays if I remember correctly - they're almost all package deals and charters. By the afternoon on those two days the temperature drops several degrees celsius and you'll see clouds. I even saw a dribble of rain once.

I was a complete skeptic when I was told this as I arrived, but like clockwork on those days I always saw the same thing. The crazy thing is that any other day of the week around the summer you can expect mid-to-high thirties and rarely a cloud in the sky. So maybe not scientific, but anecdotal evidence anyway.

Potential AGW support?

[OzPeter]

I'm not deep into the AGW/anti-AGW arguments (and not trying to start a flame war), but I thought that one of the anti-AGW arguments was that in general humans can't affect climate. This sort of research would seem to suggest that humans can affect climate and hence nullify some of the anti-AGW stance - or are these effects so localized that you can only state that the humans are affecting weather and not climate?