Zapping Contrails With Microwave Emitters 125
An anonymous reader writes "Dissipation of contrails with a powerful microwave beam aligned behind aircraft engines is being touted as a possible solution to help address air transport's effects on the climate. 'The remote heating of condensation nuclei could be achieved by applying electromagnetic radiation, such as microwaves,' says Cranfield University's Frank Noppel. 'Depending on assumptions made, calculation shows that the power required for such a device could be as little as 0.1% of the engine power.'"
Re:Why.... (Score:4, Informative)
Logic abounds! (Score:4, Informative)
Dare I say...BRILLIANT!
Actually, I wonder what effect this would have on those pesky naturally occuring clouds...
Re:I'm confused (Score:5, Informative)
No it isn't. Studies have shown that temperatures rose significantly across the US right after 9/11 when all planes where grounded for several days, because of clearer skies.
See here. [berkeley.edu]
Re:Why.... (Score:1, Informative)
Another study that took advantage of the grounding gave striking evidence of what contrails can do. David Travis of the University of Wisconsin-Whitewater and two colleagues measured the difference, over those three contrail-free days, between the highest daytime temperature and the lowest nighttime temperature across the continental U.S. They compared those data with the average range in day-night temperatures for the period 1971-2000, again across the contiguous 48 states. Travis's team discovered that from roughly midday September 11 to midday September 14, the days had become warmer and the nights cooler, with the overall range greater by about two degrees Fahrenheit.
These results suggest that contrails can suppress both daytime highs (by reflecting sunlight back to space) and nighttime lows (by trapping radiated heat). That is, they can be both cooling and warming clouds. But what is the net effect? Do they cool more than they warm, or vice versa? "Well, the assumption is a net warming," Travis says, "but there is a lot of argument still going on about how much of a warming effect they produce."
Re:I'm confused (Score:5, Informative)
From the wiki article it sounds suspiciously like contrails have a warming effect when they're produced either a) at night or b) during the winter. From the percentages listed, it appears that the contrails may well have a cooling effect if they're produced during the day and/or not during the winter. That makes the assertion that the net effect is heating a little easier to swallow.
No, I didn't check out the typically mangled Wikipedia reference. Seriously... citations are great, but you use journal abbreviations and short form references when you're trying to cram them onto one page abstracts, NOT when you're putting them on web pages where space is free.
Re:I'm confused (Score:1, Informative)
Correllation != Causation
Re:Nice, but ultimatly useless... (Score:3, Informative)
Define "green". If you're using it in the common manner, it means one or more of the following:
Reduced carbon footprint
Reduced toxin output
Reduction of resources required to produce
Reduction of resources required for operation
And note that this is per unit of work, whether that is passenger-mile or some other measure of work.
Note that while substitution of resource requirements can go either way with cost, reduction of resources for operation will by definition reduce cost.
Maybe you feel that it's not "going green" if there is an economic incentive to take "green" actions, but I don't make that distinction. Hell, I'd consider the airlines' choice to charge for each checked bag to be a green move, since it reduces fuel usage.
Re:I'm confused (Score:4, Informative)
or Virgin Galactic/Scaled Composites [wikipedia.org], who in turn based their design off of the Soviet Myasishchev 3M-2 [ussr-airspace.com].
Re:I'm confused (Score:3, Informative)