Ahead of today's second session, the air temperature is 21 degrees C, while the track temperature is 26 degrees. The temperatures having dropped quite considerably since the first session, then again it is approaching 16:30. There is now a fairly heavy layer of cloud hanging over Albert Park, and even a few spots of rain.

Tyre options this weekend are hard (prime) and soft (option).

Kobayashi was the cause of two red flags this morning, the first when he lost his nose after colliding with a cone while the second came about when his new nose mysteriously fell from the car causing him to lose control and go off into the gravel trap, never to return.

As we await the green light, Buemi is heading a queue at the end of the pitlane, the Spaniard's car shod with option tyres.

The Toro Rosso driver is followed by Kovalainen, de la Rosa, Trulli, Hulkenberg, Webber and Kobayashi as rain begins to fall in earnest.

While most drivers head back to the pits after an installation lap, the Sauber duo continue around.

While Kobayashi slides around, the rain clearly falling harder, de la Rosa tells his crew; "there's too much rain now!"

Twelve minutes into the session, after several minutes of total inactivity, Sutil - back in the Force India after Paul di Resta drove it this morning - heads down the pitlane. Shortly afterwards, he is followed by the two Williams drivers.

Barrichello posts the first time of the session, the Brazilian veteran crossing the line at 1:31.006. Teammate Hulkenberg can only manage 32.971 as several more drivers, including Mark Webber, venture out.

As Barrichello improves with a 27.585, more and more drivers pour on to the track, the earlier shower having stopped and the track dry but for one or two minor damp patches.

Rosberg posts 27.464 as Kubica goes third (27.746), ahead of Hamilton, de la Rosa, Hulkenberg and Liuzzi.

No sooner has Button gone quickest with a 26.735 then he is eclipsed by his teammate (26.648) despite a major slide in the final corner.

Button re-takes the top spot with a 26.076 as Petrov goes third, despite running very wide at Turn 13. Hamilton posts 25.801 to go quickest, the two British champions enjoying a great in-team scrap.

As Sutil moves up to fourth, ahead of Rosberg, a few more spots of rain begin to fall.

Chandhok grind to a halt just a few yards after leaving the pitlane. The Indian climbs out of his car, replaces the wheel and jogs back to the pits.

Button is still on track, running on the option tyre, and as a few spots of rain blur the camera lens it is clear the Englishman is trying to get in as many laps as he can before conditions deteriorate. Elsewhere, Rosberg visibly backs off and heads back to the pits as do Alonso, Kubica Vettel and Alguersuari. Button also opts to head back to the sanctuary of his garage.

With 53 minutes remaining, all the drivers are in their garages, as the rain is falling harder, witness the multitude of umbrellas and pac-a-macs in the grandstands.

Alguersuari is back on track on wets, the Spaniard currently nineteenth of the nineteen drivers who have posted times. Still no time from Schumacher, or the Virgin and HRT drivers.

Rosberg, Petrov, Kubica, de la Rosa and Schumacher join Alguersuari as the rain appears to cease.

Barrichello tells his crew that he doesn't see any point in going out at present, as former Ferrari teammate Schumacher posts his first time of the session (39.944).

The drivers are in a quandary it's not dry enough for slicks and not wet enough for the wets. Complaining of graining on his front-left tyre, Schumacher heads back to the pits. Sutil and Petrov both clearly struggling for grip.

With half an hour remaining, the track appears dry but with the threat of further showers in the air, and the track surface still greasy, only a handful of drivers - Buemi, Kubica and Alguersuari - are on track.

As Buemi runs wide and on to the grass at Turn 15, it's clear that conditions are still not ideal.

With fifteen minutes remaining, Barrichello is back on track, on option tyres. This is the signal for Webber, Alonso and Massa to return to work.