Opening the car door during a heatwave feels like unleashing the unyielding violence of hell itself. Getting into that willingly is one thing, but shutting the door? A particularly sick form of masochism.
And yet it cannot be avoided. There are places to go, people to see and iced coffees to overpay for – and so we’ve got to find ways to cool our cars down.
If you are a forward planner, you might have already secured the spot in the shade on your street, keeping your car out of direct sunlight.
But for the rest of us who didn’t take mitigating steps, mathematician and broadcaster Hannah Fry has a recommendation. In a video viewed 10 million times since posting 11 months ago, she shares her own tip for cooling a car quickly as well as the science behind it.
Her tip is to open a window diagonal to your own car door and then, without shutting the door entirely, waft your car door rapidly. She explains that “the reason why it works is that when you open and close the door, especially if you do it quickly, as the door is moving outwards, it sweeps out all of the air that’s in the way”, aka the hot, muggy air. This creates an area of low pressure by the door which sets up bulk flow. “All of the horrible, hot air is drawn outwards, and the only way to refill it is with the cool, fresh air from the back”. And as if by magic (or physics), the car is cooled.
