Have you ever noticed how hot it can get inside a car on a summer day — far hotter than it is outside! That’s because a car acts like a greenhouse (called the “Greenhouse Effect”) trapping the sun’s heat.
Check out this animated video of the Greenhouse Effect in action on a hot car, by the cool people at Golden Gate Weather Services.
The below study by the Animal Protection Institute showed that hot temperatures outside can quickly lead to deadly hot temperatures inside a closed car. This study was conducted during a local heat wave in Sacramento CA. However, notice on day three, the temperature starts out at a reasonable 72 degrees.
This study compared an outside temperature of a shaded area with the inside of an automobile in three states: fully closed, with four windows cracked, and with two windows cracked. Inside temperatures were measured with an indoor/outdoor thermometer and an oven thermometer (both readings are given). All temperatures use the Fahrenheit scale.