This is an interesting time of year for many reasons, not all of them connected. Summer is gradually giving way to autumn, in Britain at least. The swallows are gathering in preparation for the long flight south. The harvest is safely in, the evenings are cooler and the cats are coming in at night.

And the Formula 1 World Championship comes to the forests of the Ardennes where it almost always rains – a time for both reflection and some anticipation.

In the space of seven days we will have visited two motor racing circuits that neatly illustrate some of the problems faced by contemporary Grand Prix racing. The European GP in Valencia was, unsurprisingly, not a huge success. It is reported that 80,000 people went to watch the cars last weekend, and that is not nearly enough. Aside from this, the circuit needs to be laid out in such a way as to make overtaking a possibility. Motor racing without overtaking, like top-level football without any goals, is not grippingly exciting. In the case of Valencia, this is a shame, because – while it is far from being Monte Carlo – it is an interesting city with some sensational modern architecture. With a new five-year contract in their pockets, the organisers need to consider what can be done with their asphalt.

The forthcoming race at Spa-Francorchamps will be a different story. The cars will be the same but they will be on a proper circuit, one of the best in the world, and there will likely be some racing. There is, as ever, much talk of ‘dirty air’ and the Overtaking Working Group’s apparent failure to adjust the rules in ways that will allow the cars to pass each other. But this is only part of the story. A casual glance at the grids so far this season underlines just how competitive 2009 has been, how closely matched the cars are. While Valencia is virtually a ‘tunnel’ between concrete walls, Spa swoops around wooded valleys where there is more chance of this ‘dirty air’ being less of a problem. Not having a degree in aeronautical sciences, I do not pretend to comprehend the finer points of aerodynamics and the effects of airflow at high speed. But I do know that a Grand Prix driver would rather pit himself against the demands of Spa than the oppressive contortions of Valencia. To walk out into the woods at Spa and watch an F1 car at flat chat is one of the sport’s great experiences. Just to hear them approaching sends a shiver down the spine.

So, we approach an interesting juncture. Jenson Button is oddly off form. But the Brawn is clearly still a very quick car and Button, mathematically at least, must be the favourite. Lewis Hamilton is back on form and the McLaren looked mighty impressive in the high-speed stuff at Valencia. Sebastian Vettel has only two Renault V8s left to take him to Abu Dhabi. And that’s a worry, because the French motors have shown no such weakness in the back of the works cars. Mark Webber wants it badly but needs to win. Rubens Barrichello is on one of his highs. Something tells me that the Belgian Grand Prix may be a turning point.

If all this seems inconclusive, there are always the motorcycles. This weekend MotoGP returns to North America where Rossi will demonstrate how to do the perfect lap of Indianapolis on two wheels. Remember last year in the rain? Breathtaking. This year, however, it is more likely to rain in Belgium than in Indiana.

What a weekend in store then – the Grand Prix cars at Spa and the big bikes at Indy. For those of us in Europe, the time zones are in our favour, enabling us to savour what should be two great motor racing events. Make the best of it, the evenings are drawing in.