Geoengineering

Or 'persistent contrails' as they are called at this symposium:

http://www.globalresearch.ca/atmospheric-geoengineering-weather-manipulation-contrails-and-chemtrails/20369

Do you believe me or your lying eyes? FWIW, this is why the European weather has been abysmal this summer, with at least 20% less sunlight reaching the earth (and preventing photosynthesis) - Solar Radiation Management, which you can see from this wiki definition is "largely theoretical":

http://en.wikipedia.org/wiki/Solar_radiation_management

Meaning, of course, that they're doing it now, above your heads. Is this what they're scared of, Solar cycle 24?:

http://en.wikipedia.org/wiki/AR1429#March_2012

Geoengineering explained:

 http://www.youtube.com/watch?v=a2x6TEeknfo&feature=player_embedded

And here's a quote giving away what they're actually doing, in a dreadful article in a pseudo-'scientific' journal:

 "Slightly less dramatic, and more feasible, are schemes that would spray aerosols, or tiny particles, high in the atmosphere.

These aerosol plans are based on nature. Volcanic eruptions spew sulfur dioxide gas high into the atmosphere, which combine with water vapor and form light-reflecting particles. Just like the theoretical space shields, these particles keep Earth cool.

A variety of methods could be used to get these aerosols into the atmosphere, from spraying them out of airplanes to one plan that would use a balloon tethered by a 12.4-mile-long (20 km) hose pumping the particles into the stratosphere."

from:

 http://www.livescience.com/37865-how-to-engineer-the-climate.html

(my bold highlights - this is what they are doing, now)