Busy Sky over Southern UK - July 30 2014

A very busy-looking sky this morning over Hampshire, UK (July 30 2014).

I noticed it this morning. The contrails were persisting nicely in the humid calm air, gently "feathering" (I call it) southwards. It's clouded over now (not surprisingly) with contrails still persisting in the "blue" bits.
As this has spun off into its own thread, here are a couple more relevant photos. Amid all the trail frenzy I noticed one plane that wasn't leaving a persistent trail:

I then managed to fire up FR24 in time to get an identification, which explains it:


Air France flight 11 from JFK to Paris was flying at 39,000 feet.

At the same time, and in the other direction, I watched a couple of planes at 36,000ft leaving trails from horizon to horizon.
A few hours later and the skies were totally clear by late afternoon. (I'm in London now, about 35 miles away from the first photos.)


Again, the reason can be seen on the humidity map:

The brown colour shows much drier air having moved in.