White cars are commonly believed to stay cooler than darker-colored vehicles, particularly on hot, sunny days. Understanding the science behind this phenomenon clarifies how a car’s color impacts its internal temperature.
How Car Color Affects Heat Absorption
A car’s color significantly influences how much solar radiation it absorbs. Solar radiation, including visible, ultraviolet, and infrared light, carries energy. When sunlight strikes a surface, some energy is absorbed and some is reflected. Darker colors, such as black or dark blue, absorb a larger percentage of this spectrum. This absorption converts light energy into thermal energy, causing the surface to heat up.
Conversely, lighter colors, particularly white, possess higher solar reflectance. They reflect a greater proportion of incident sunlight away from the car’s surface. By reflecting more energy, less is absorbed and converted into heat. Material emissivity, its ability to radiate absorbed heat, also plays a role, though reflection is the primary factor for color-based temperature differences.
Real-World Temperature Differences
Studies have investigated temperature differences between light and dark-colored vehicles exposed to direct sunlight. Research indicates a dark-colored car, like black, can reach significantly higher exterior and interior temperatures compared to a white car in similar conditions. For instance, a black car’s exterior surface might be 15 to 20 degrees Celsius warmer than a white car’s surface on a sunny day.
Interior cabin temperature also reflects these external differences, though to a lesser extent. A Berkeley Lab study found a black car’s cabin air temperature can be 5 to 6 degrees Celsius higher than a silver car’s after an hour in the sun. These temperature variations are measurable and influence comfort inside the vehicle and the energy required for air conditioning.
Other Factors Influencing Car Interior Temperature
While car color contributes to interior temperature, several other factors also play a role. The type and color of a car’s interior upholstery can influence heat absorption. Darker upholstery materials, similar to exterior paint, absorb more heat and can feel hotter to the touch.
Window tinting is another important factor, as it blocks significant solar radiation from entering the car. Reflective sunshades on the windshield and other windows also reduce heat buildup by reflecting sunlight before it enters the cabin. Effective ventilation systems and parking in the shade rather than direct sunlight also significantly impact how hot a vehicle becomes.