A variable forecast over the remainder of the Belgian Grand Prix weekend, with rain expected for qualifying ahead of a dry race, will cause Formula 1 teams a set-up dilemma.
In dry conditions, the Spa-Francorchamps circuit requires an aerodynamic set-up that prioritises efficiency; downforce is an important factor as drivers need to carry speed through the variety of medium-to-high speed corners around the 4.3-mile circuit, but top speed is also vital. Thus, teams tend to pursue lower-drag wing concepts to minimise any inefficient sources.
Wet weather requires a very different approach, as it's important to load up the tyres in low-grip conditions to keep them warm and ensure the drivers remain adhered to the road. More downforce is needed in that instance, with little regard for efficiency as the cars rarely top out at the end of longer straights.
A driver expected to figure towards the front will not wish to sacrifice qualifying, as this can severely dent their chances to make progress through the field, but equally cannot afford to enter the race with a surplus of inefficient downforce. Thus, it's a fine balancing act between the two modes.
The latitude for changes on either side of parc ferme - which comes into effect when the Q1 session ends - is small, even with the allowances made for a change in climatic conditions.
Front wing flap angles may be adjusted, but only using the existing bodywork used in qualifying. Thus, if a team opts to use a high-downforce wing in qualifying, it may not switch specification without penalty.
When a change in conditions is declared by the race director, the rules state that "components specified in Articles 3.13.3 and 3.13.4 of the Technical Regulations" may be swapped out - which relates to the brake ducts within the wheel bodywork. Outright swaps between wing specifications will be met with a pitlane start.
Forecasts suggest that there will be no rain on Sunday, so it makes little sense to throw everything at a higher-downforce qualifying set-up and hope for the best; overtaking at Spa is much more achievable compared to most circuits, and thus it leaves a driver vulnerable in the race if they can't develop enough speed on the straights.
This also extends to suspension set-ups too: again, developing tyre temperature in wet conditions will be a vital component of a good grid position, but sticking to that in the race puts a driver at risk of overheating their tyres and compromising strategy.
Thus, it's up to the teams to select the best compromise. If it is confident that it can qualify well in a wet session with a lower-downforce set-up, or that it expects conditions throughout the session to remain variable, then it could opt to focus on a race set-up and take what it can in qualifying.
One driver can go all in for the race: Yuki Tsunoda. The Japanese driver will start from the back of the field either way, having taken a full set of new power unit components, and thus RB can trim its wing levels for Tsunoda to ensure he has the right set-up for Sunday.
Those expected to feature at the rear of the field - ie. Sauber - could also get away with sacrificing grid position for a stronger car on Sunday. Depending on a team's expected competitiveness, the set-ups may vary from calculated risk to complete gamble.
And if it doesn't rain? Then the preceding 500-plus words are moot, and it'll also make the teams very happy. But as fans, we'd probably prefer the drama: a weekend with changeable conditions is where the engineers really earn their crust...
