UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
I have been searching for an answer to this question for quite some time. Do different colors 'reflect' heat at different rates? I am not talking about light at all. In a dark room, will different colors reflect HEAT at different rates? I believe that I know the answer, but have not been able to find it anywhere.
Answer 1:

The answer is yes, color matters, but only for a specific definition of "color" which you might not expect. Visible light is just a particular spectrum of wavelengths in the electromagnetic spectrum that our eyes have evolved to be able to see. "Color" describes which of these visible wavelengths are absorbed or reflected.

When we talk about "heat" that can be reflected or absorbed we are usually referring to electromagnetic radiation in the infrared spectrum, because hot object give off electromagnetic radiation mostly in the infrared spectrum*. So the "color" of an object will affect how much infrared light is absorbed, but the color that matters isn't the color that we can see, but the "color" in the infrared spectrum. Some objects will appear white if viewed under infrared light with an infrared camera, because they reflect most heat. Other objects will appear black because they absorb most of the heat and don't reflect it to the camera.

The short answer is that color matters, but it's the color in the infrared spectrum which controls how much heat will be reflected by an object.

*The radiation given off depends on the temperature. Objects up to around 500 degrees Fahrenheit, like the hot walls on the inside of an oven, or a pan on a stove, will not give off any visible light, but they will give off a lot of infrared radiation. Around 900 degrees F you will start to see a red glow. Extremely hot objects like the sun, around 10,000 degrees F will give off most of their radiation as visible light. The physics and math describing this are known as "black body radiation".


Answer 2:

It has nothing to do with the color of the object in visible light. Light comes in many more colors that you can't see than those that you can. Heat is actually huge number of different colors, none of which you can see, and objects have their own colors in the heat range as well as in the visible light range. For example, your skin is very dark in the heat colors and absorbs a lot of heat, but a sheet of metal painted the same color as your skin will be much more reflective in the heat part of the spectrum.



Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2015 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use