Airplanes May Affect Weather Patterns

blankmange writes "Wired is carrying an interesting piece: '...for three days starting last Sept. 11, meteorological researchers were presented with just such an opportunity when the FAA grounded commercial flights nationwide for three days following the terrorist air attacks. And now it has emerged that the American climate was indeed noticeably different during those three days without air travel.' Seems that what we do on the planet may have more effect than we may ever know."

Comments

Re:buildings

[HeyLaughingBoy]

Also, in the summer almost all of the buildings have A/C running full throttle. I think all of the waste heat that is blasted outside ends up raising the temperature an appreciable amount.

Actually the streets have a greater effect. Power sources and the huge amount of blacktop (streets) absorbing the sun combine to create a "heat island." I took a meteorology course long ago and we learned that the temp over NYC was usually about 10F higher than the surrounding areas. It definitely has an effect on weather. Around here, it's been noted that the temperature differential of the city causes some storms to be deflected slightly as they go past.

Re:Vulcanoes and stuff

[shrikel]

The amount of dust and debris that were thrown into the air on 9/11 was far, FAR too little to have a significant impact on the climate. (Other than the chaotic butterfly effect, of course.) Compared with some of the larger volcano eruptions just in RECENT history, the WTC dust was just a cup of water compared to all the water in the Great Lakes.

I don't know what the short-term, localized (to NYC) effect it had. Probably measurable, but certainly not widespread.

Re:buildings

[Black Aardvark House]

I used to live in NYC. The urban heat island effect is most noticeable on summer nights. During heat waves the nighttime temperatures can be as high as 93 F at 1 AM and lows may reach only the upper 80's.

All this at almost 41 degrees north latitude!

NYC also gets substantially less snow for the same reason.

Re:Vulcanoes and stuff

[Matthias Wiesmann]

The problem with volcanoes, as far as I understand, is that the ashes are propelled quite high in the atmosphere, and thus can spread far and wide, sometimes thousands of kilometers away. Debris from the WTC probably did not go further than a few blocks. I don't think it makes sense to put the explosion of a building, even a large one, in the same category than a large volcano.

Also, large buildings are blown up all the time when they are demolished - albeit usually there are no people inside. But from the meteorological point of view, it proably makes little difference.

Re:Alternative?

[ghoul]

As far as I know besides the NOX emissions at high altitude the problem was also that high speeds create Ozone due to heat which leads to ground level Smog (Note Ozone very High Up-Good; Ozone Ground Level/Stratosphere -Bad)

The problem of high speeds creating ozone would remain even if we used Hydrogen jets

clouds [contrails] and their effect on climate

[dolsen]

here's a nice image that illustrates (from low earth orbit) contrails over a large area (Nova Scotia, Canada, to be exact). at the NASA rapidfire site [bandwidth intensive] you can basically pick any day, choose an image over the northeast of the US [approx. 15:00 to 16:00 UTC normally] and it's a good bet you'll see lots of contrails. they have to have some impact on at least the local climate of the northeast. if you're in the mood for some light reading you can check out several NASA reference articles about clouds and their affect on climate:

• Changing Global Cloudiness Clouds are visible collections of small particles of water or ice, or both, suspended in the atmosphere. They are one of the most obvious and influential features of Earth's climate system. They are also one of its most variable components.
  
  Aerosols and Climate Change Aerosols are tiny particles suspended in the air. Taken as a whole these particles tend to cool Earth's atmosphere, and are an important factor in global change.
  
  Clouds and Radiation The study of clouds, where they occur, and their characteristics, play a key role in the understanding of climate change. Whether a given cloud will heat or cool the surface of the Earth depends on several factors.

there's also a good page on how ship tracks affect climate

oh yeah, the NASA press release about the contrail study...