[NeedInfo]Persistent Contrails Picture Show

Here is my journey through France. Dijon / Lyon / Metz.

This was on 18th of May 2015.

Here is the exact route:


Anyone got weather data (humidity / temperature etc.) for this case? Or know where to look for it?

Here is the gallery, have fun:

You can find upper-air relative humidity and temperature charts at instantweathermaps.com , with a three-day archive free of charge.

Here are the humidity charts for 9am, 12 noon and 3pm UTC (11am, 2pm and 5pm Central European Summer Time) on May 18:




As you can see there was an area of very high (>90%) humidity at the 300mb level (30,000 feet) over northeastern France at that time.

The temperature at 300mb was between -42.5C and -45C. For instance this is the chart for 1200 UTC:


The scale is only graduated to 2.5C but based on the position of the -42.5C and -45C isotherms I would estimate the temperature over Metz to be about -44C.

That suggests good conditions for persistent contrails, as seen on the Appleman chart:


Taking the temperature as -44C, the required RH for persistence is 90% at 300mb.