Ahead of today's second practice session the air temperature is 20 degrees C, while the track temperature is 22 degrees. Following this morning's wet session the rain eventually stopped and the track began to dry. Then, about fifteen minutes ago, it started raining again.

The tyre compounds this weekend are hard and medium, though in both of today's sessions teams have had access to the latest-spec 2014 prototype tyres... not that they got to use them. Saying that, Vettel did run one lap on them before being told to pit... his team claiming it already had sufficient data.

There are two DRS zones, one on the main pit straight and the other on the back straight between Turns 3 and 4.

Around five minutes after the lights go green Chilton ventures out, the Englishman replaced by Rodolfo Gonzalez in this morning's session. Chilton completes two laps before returning to the pits, at which point, presumably to keep the fans entertained, Kovalainen takes to the track.

Chilton reports standing water puddles, especially at the entry to T12 on the right-hand side of the braking zone.

The Finn completes a full lap, crossing the line at 1:31.658.

As Bianchi heads down the pitlane, Kovalainen improves lap after lap.

"It's raining heavier now," says Kovalainen as he heads into the pits, "I'm aquaplaning in a couple of places now." Bianchi posts 34.565.

As Bianchi gets down to 33.250, Webber is told: "OK, track is clear, track is clear", at which point the Red Bull driver leaves his garage.

On his first flying lap Webber posts 30.645, watched by a smiling Vettel who shows no sign of going out just yet.

A 29.088 sees Webber go quickest as Van der Garde goes third (31.550) ahead of Pic and Bianchi.

On his first flying lap, Rosberg goes quickest with a 28.873, the German immediately slowing and saying "that's enough for me". "Ross says you're the only person dumb enough to be out there at the moment," comes the response.

Fact is that other than being treacherous, the fact that we are expecting rain tomorrow and Sunday leaves the driver in a quandary as they are limited in the amount of inters and full wets they have available.

At half-time, with only twelve names on the sheets, it's: Rosberg, Webber, Grosjean, Hulkenberg, Ricciardo, Kovalainen, di Resta, Van der Garde, Bottas and Pic.

With all running on wets thus far, Ricciardo is informed that the wet to Inter crossover lap times are -0.5s inS1, -2s in S2 and "at crossover time" in S3.

With half-an-hour remaining, the Sauber duo are the only drivers on track. Hulkenberg is fifth (30.010) as Gutierrez goes eighth (30.723).

Hulkenberg reports struggling with front brake locking and high speed understeer. "Tried to adjust brake balance, but it did not help," he says. "It just feels like we're just running against a wall in terms of grip, lap time, everything" he adds before pitting.

As Gutierrez improves to sixth, having gone fastest in S2, Alonso heads down the pitlane on Inters. Stefano Domenicali watches nervously. Moments earlier, asked if it was time to switch to Inters, Bianchi was in no doubt: "It's too early, it's too early," he said.

The Spaniard goes tenth (31.184), 2.311s off Rosberg's pace. However, next time around he goes quickest in S1. Posting a PB in S2 he crosses the line at 29.410 to go third overall.

Clearly inspired by Alonso, a number of drivers including Webber switch to the Inters.

With 14:42 on the clock we've yet to see Vettel, Button, Hamilton, Vergne or Sutil make an appearance. At which point, as you might have guessed, Vettel and Vergne head down the pitlane. Both are on Inters.

Hulkenberg (wets) goes quickest in S1 as Webber reports that his KERS has failed. The German remains sixth (29.885) having had a poor final sector.

On his first flying lap Vettel goes fifth (29.800), 0.927s off Rosberg's pace. Next time around however he goes quickest in S1. A PB in S2 is followed by another in S3, the world champion crossing the line at 28.839 to go second.

Almost everyone on Inters now.