What Are These Wingtip Vortices in Formula One Cars and What Couse Them?
Take a look at the video above to visualize what I am on about.
These vortices are called "Wingtip Vapor Vortices".
This phenomenon is a combination of Aerodynamics and Thermodynamics.
Aerodynamics
From the Aerodynamics part we should know that the rear wings in Formula One cars are to produce downforce; therefore, they are designed in the way that at the top of the wing high pressure area would be created and at the bottom of the wing high velocity and low pressure. However, the air naturally has the tendency to move from high pressure to low pressure to balance things out; hence, at the wingtips (which is the endplate of the rear wing) high pressure area will move towards the low pressure and build a vortex which involve high energy region (high velocity and pressure) at the end of the rear wing.
Keeping the Aerodynamics of this effect in mind, in order to understand the visibility of this we need to get some help from Thermodynamics.
Thermodynamics
Assuming that this phenomenon is adiabatic (which means no heat exchange between the system and its surrounding) we can refer to thermodynamic equation of adiabatic process, which indicate that by increasing the pressure inside the system (the vortex), temperature will enhance as well. Similarly, with decrease in pressure of the system, temperature of the system declines.
Also, the Dew Point should be taken into account in this explanation. Simply put, Dew Point is the temperature which cooler than that at certain pressure, the airborne water vapor will condense to form liquid water drops (the transition temperature from gas to liquid, corresponding to partial pressure of water vapor).
Combination of Aerodynamics and Thermodynamics
When the vortex forms, its pressure (inside the vortex) starts to decrease very fast as it blend to ambient pressure. This reduction in pressure, cause a significant diminish in Dew Point; therefore, the vapor in the air starts to make liquid water drops at ambient temperature and that is why we can see those wingtip vapor vortices at the back of the rear wing Formula One cars.
References:
1)https://www.sportskeeda.com/f1/wingtip-vortices-in-formula-one-why-are-they-formed , 2)https://en.wikipedia.org/wiki/Dew_point#:~:text=The%20dew%20point%20is%20the,will%20condense%20on%20the%20surface. 3)https://www.reddit.com/r/formula1/comments/9lwtyo/vapor_trails_visible_off_h%C3%BClkenbergs_rear_wing/