Ahead of today's opening practice session, the air temperature is 9 degrees C, while the track temperature is 11 degrees. It is unseasonably cool; indeed, some claim it is "freezing", while there has been a fair amount of drizzle for the last couple of hours. Overall, it's what you'd expect at Silverstone not Istanbul.

That said, for the last week, the experts have been predicting such weather for much of the weekend - but then that's not the first time we have heard such predictions this year.

This being the first round of the European season the teams finally have their motorhomes at their disposal, some of them having undergone significant revamps. Arguably the best looking of the lot is that of Pirelli, which has a very sexy (black) carbon fibre finish.

Being the first round of the European season, and following a three week break since China, nearly all the teams have upgrades on their cars - some more than others.

As the lights go green, signalling the start of the session, the rain has increased in intensity, Charlie Whiting officially declaring this to be a wet session.

Di Resta gets the weekend underway, the Force India driver heading down the pitlane followed by d'Ambrosio, Ricciardo, Buemi, Trulli and Glock.

On his out lap, Karthikeyan pulls off to the side of the track, his session over barely before it's begun.

Ten minutes into the session, everyone bar Hamilton and Kobayashi has been out, some on full wets some on intermediates.

Twenty minutes into the session, as most drivers chat with crew members, Hamilton heads down the pitlane. No sooner has the McLaren driver returned to the pits than d'Ambrosio, Ricciardo and Buemi are back on track splashing around.

The Belgian posts the first time of the day, crossing the line at 1:49.518. Moments later Buemi posts 41.632.

From the relative comfort of the Red Bull garage, Sebastian Vettel - sporting a Billy Whiz style haircut - watches along with Helmut Marko.

Massa is the first of the big guns to make a second run, the Brazilian carrying out back-to-back tests with an old front wing and a newer version. The car is also carrying a video camera in order to give the team more detailed feedback.

After thirty minutes there are just four names on the timesheets, Buemi, Ricciardo, d'Ambrosio and Glock.

Rosberg goes third with his first flying lap (42.166) as fellow German Nico Hulkenberg, at the wheel of Sutil's Force India, posts 42.447 to go fourth.

A 42.474 sees Alonso go fifth as Hulkenberg improves to second with a 41.437.

Buemi finally loses his place at the top of the timesheets when Alonso posts a 40.897. However, he is told on his next lap that his full wet tyres are "going away", as the track appears to be moving towards the intermediates.

Rosberg, on wets, goes quickest in all three sectors, crossing the line at 40.072 to go quickest. The German heads straight back to the pits just as teammate Schumacher heads down the pitlane.

Replay shows di Resta having a major wobble having run across a very slippery white line. Meanwhile, Schumacher is warned that there is aquaplaning at Turns 2 and 11.

Schumacher goes third with a 40.954, the German always a master in these sorts of conditions. Moments later however, Japanese hotshot Kobayashi posts a 40.580 to go second.

As Glock proves that the warning about aquaplaning at Turn 11 is correct, Heidfeld goes second and Renault teammate Petrov third. Elsewhere, a 42.564 sees Webber go tenth.

Alonso is back on track on intermediates but he isn't happy. The team inform him that they need the data and that he only needs to do one lap.

Having fired up Vettel's car, his crew switches it off again as the rain increases in intensity.