Ahead of today's second free practice session the air temperature is 31 degrees C, while the track temperature is 35 degrees. The Humidity is 43 percent. It is 17.00 (local time) with sunset officially due at 17.44.

With it being a brand new circuit, and therefore dirty and dusty, there were numerous little incidents this morning, with Turn 19, in particular, catching out a few drivers.

While the Red Bull and Brawns looked good this morning, as did pace-setter Hamilton, the Ferraris were disappointing. Not a good start seeing as the Maranello outfit hopes to take third place in the constructors' Championship from McLaren.

The lights go green and Alguersuari leads the way, followed by Rosberg, Vettel, Heidfeld and Buemi.

The tyre compounds available this weekend are medium (prime) and option (soft), though the option tyres weren't used this morning.

Within three minutes of the start of the session there are seventeen drivers on track, only Trulli, Kobayashi and Liuzzi remain in their garages.

Rosberg is the initial pace-setter, how his time of 47.576 is soon beaten by Button who crosses the line at 47.116.

While there is still some natural light - though the overhead spotlights are already in action - the pace is fast and furious. Nakajima, Heidfeld, Kovalainen, Alguersuari, Buemi and Kubica all eclipse Button's time.

Hamilton makes a mistake on his first lap however, next time around he posts 44.616 to go sixth. On his third flying lap he crosses the line at 43.664 to go quickest. Elsewhere, Nakajima says that conditions are markedly different to this morning.

Kovalainen goes quickest with a 43.601 making it a McLaren 1-2, only to be leapfrogged by his British teammate with a 42.942. Elsewhere, Sutil, who has spun underneath the bridge, tells his crew he has a brake problem.

Button improves to third, just behind Buemi who goes second then improves to yet again (42.729) to go quickest.

As Buemi raises the benchmark with a 42.526, Webber remains the only driver yet to post a time.

Raikkonen can only manage eighteenth, 2.839s off the pace, one place behind his Ferrari teammate.

Trulli asks for a smaller windscreen, the Italian complaining that the screen on his Toyota is casting a shadow which makes visibility difficult.

Webber goes seventh with a 43.328, the Australian, like Button and Buemi is now running on the option tyre.

Thirty minutes into the session the driver appear to be concentrating on long runs as opposed to going for fast times. Even the (few) drivers on softs are not pushing too hard.

That said, Webber (option) goes second and Vettel (prime) fifth as Hamilton complains that his backside is getting hot, no doubt due to the fact that the ride height on the Brawn is very low.

Button (option) goes second with a 14.669, albeit 0.526s off Buemi's pace.

Still on the prime tyre, Hamilton goes quickest with a 41.843, the McLaren driver first to dip into the 1:41s. Elsewhere, Grosjean runs very wide, the Frenchman clearly struggling here today.

Kubica's session comes to an early end when his engine suddenly detonates. The Pole, who is heading to Renault next year, having suffered a number of similar failures this season. BMW will be hoping for better things in its F1 swansong.

Kovalainen and Buemi both break the 1:41s barrier, the Finn improving to within 0.096s of his McLaren teammate.

At half-time, it's: Hamilton, Kovalainen, Buemi, Barrichello, Vettel, Raikkonen, Button, Rosberg, Kobayashi and Webber.

Webber (back on primes) goes quickest in the first sector and posts personal bests in the second and third, crossing the line at 42.399 to go sixth.

With thirty minutes remaining, the sky is now almost pitch-black however, the floodlights do their job bathing the track in bright light.