Thursday, July 18th 2019, 4:26 pm - Now that warm weather is here, firefighters are reminding the public not to leave plastic water bottles in their cars.
When the heat, sun, and the bottle lines up just right it can cause a small fire. If the sun is strong enough, a bottle can act like a lens that channels light into a high-powered beam, strong enough to burn a car's upholstery.
As a case in point, Idaho Power uploaded a video to YouTube in 2018, featuring a water bottle burning two small holes into a car.
"This is a good illustration of just how much energy there is coming from the sun," Michael Doutre, a chemist at the Getty Conservation Institute who studies plastic, told Live Science.
"We think of this as a cheap water bottle, but we're unintentionally creating an optically almost-perfect shape for a lens."
Doutre told the outlet that after sunlight passes through a car window, it can hit a seat with about 600 watts per square meter of energy, which is roughly equivalent to the heat generated by a small electric space heater.
While fire-retardant materials inside a vehicle would likely prevent it from igniting, the water bottle-turned-laser could leave behind a nasty burn mark.
For a flame to catch, the liquid in the bottle must be clear so that a sufficient amount of light can pass through.