Why weather isn’t a true F1 leveller 

The European summer of 2022 will be remembered for record-breaking temperatures and the lowest rainfall seen for many years. In spite of this, seven sessions up to the mid-season break required wet or intermediate tyres: the events in Imola, Monaco, Montreal and Budapest [plus Singapore and Suzuka since this was written - ed] were all affected at some point by wet weather.

Experience can give some indications of what weather to expect and, for new circuits, teams will scrutinise the 30-year averages for the particular location at the time of year of the race in order to ensure the correct cooling packages are available for the cars. They are, however, only averages and extremes can still catch you out. Even Bahrain, the driest country we visit, has 10 days of rain a year and although we have only ever had a dry race there it has rained heavily in March.

It’s often said that the weather is the same for everyone and even that it is some form of ‘leveller’ of performance – but is that really true?

Certainly wet weather provides a very visible set of different conditions but so too do other environmental factors such as wind, temperature, and even to some extent atmospheric pressure. Having a good handle on what weather to expect and having the tools and knowledge to handle different conditions, far from being a leveller of performance, can hand those with the correct skills a worthwhile incremental advantage.

Let’s consider wet weather first. There was a time when different tyre manufacturers were competing against each other and cars could have their set-up configuration changed at any point during the weekend. Then wet weather was a huge decision-making challenge. These days, with no set-up changes allowed once qualifying starts and just the Pirelli wet and intermediate tyre available, life is more simple but that isn’t to say it’s by any means easy.

Being on the right wet tyres at the right time, while still extracting performance, was key to Verstappen's Japanese GP win

Photo by: Red Bull Content Pool

The secret now, as indeed it always was, is to have good knowledge of what the rain is going to do. If intensity is increasing then times need to be set early in the session; if intensity is decreasing later times will be faster. Most importantly one needs to be on track when conditions are most favourable – and ideally with the car in the best state of fuel load and tyre condition and temperature that you can manage. It sounds obvious but can be very difficult to achieve.

In order to make this decision teams employ sophisticated weather radar which can track rainfall. The first to do this was Benetton in the late 1990s, but now all teams have access to a single source provided by Meteo France and administered by the FIA.

We often see the radar image on our TV screens when the weather is threatening. This system allows teams to predict the precise time rain will hit the circuit and even which corner will be affected first. This can be vital to providing the data from which decisions are made but, in F1, our needs are very different from a typical weather forecast.

One often hears drivers complaining of cars being less competitive in windy conditions. This is due to their cars having greater yaw sensitivity to that of their competitors

We need to know whether it will rain, at exactly what time, what the temperature will be and the windspeed and direction – all within the very precise area of a few kilometres and within a timeframe of approximately 90 minutes. To do this we need very accurate weather predictions, hence the reliance on a specialised service dedicated to providing just this information.

But it’s not just rain which makes up weather. Wind too has a huge effect on cars that rely so heavily on aerodynamics for performance. Basic physics tells us that, for a given aerodynamic configuration, the downforce produced is a function of the square of the speed. If the car travels twice as fast through the air then the downforce is four times as much.

If we consider the recent race at Spa, during qualifying, there was a 9km/h tailwind into Turn 5 (Les Combes) and the quickest cars were approaching this corner at 340km/h, meaning they were losing around 5% of their downforce compared with if there had been no wind.

Heat and wind are also huge meteorological factors which can impact F1 car performance

Photo by: Andy Hone / Motorsport Images

Conversely, had that been a headwind, while they may not have achieved the same top speed, they would have had a similar magnitude of increase of downforce when they started braking. Now, with straightforward headwinds or tailwinds the percentage of downforce change will effectively be the same for all cars but, if it’s a crosswind, then it’s definitely not the same for all.

All cars lose downforce in a crosswind due to what’s called yaw sensitivity. Typically a car may lose a similar 5% of downforce when it experiences the wind approaching at an apparent angle of five degrees. 

This is the yaw angle, and it can arise from both the car experiencing some yaw in a corner or a component of crosswind combining with the forward speed of the car to make the wind appear to be hitting the car at an angle. For example, at 150km/h, a crosswind of around 13km/h will appear to the car as if it were approaching at around five degrees. One often hears drivers complaining of cars being less competitive in windy conditions. This is due to their cars having greater yaw sensitivity to that of their competitors.

Finally there is temperature itself. This has two effects. Firstly, additional engine cooling required for high temperatures will always lead to a loss of downforce. The better the aerodynamics, the less the loss and the more competitive the car. Secondly, tyre temperatures are key to performance. If a car struggles to get its tyres up to temperature then a cold track will affect it more than one which heats the rubber easily.

So far from weather being a great leveller of performance the converse is true. Depending on the actual atmospheric conditions a team may have a good or a bad day; such are the fine margins between success and failure in F1.

Factors such as wind can also have a big impact on car performance if they have acute yaw sensitivity

Photo by: Sam Bloxham / Motorsport Images