UCSB Science Line
 Does blue color absorb heat? Question Date: 2014-04-04 Answer 1: The colors that your eyes detect are the colors that are reflected (bounced off) a surface. For instance, if you're wearing a green shirt, it really means that your shirt absorbs all the visible light except green. That's the only way your eye would be able to detect the green light. If your green shirt absorbed green, then green light would never make it to your eye! The same principles apply to heat! Heat can be transferred in a couple different ways, but one way is radiation. All objects radiate heat energy, even our own bodies. You may be able to guess that hotter object emit more radiation than colder objects. Radiation is transmitted by waves, and these waves can be absorbed or reflected just like light waves! If you stand in front of a camp fire, or a barbecue grill, you have experienced this: when you hold your hands out and feel the warmth, you are absorbing the heat waves coming from the fire. To answer your question more generally, all colors absorb and reflect heat, however, different colors do it better or worse than others. Typically, lighter colors reflect more heat and darker colors absorb more heat. If you've even worn a black shirt on a hot day, you'll notice this. Another example is how the blacktop pavement gets really hot sometimes: hot enough to see heat radiating from the surface! So, yes: blue does absorb heat. However, as you know, there are many shades of blue. Darker blues will absorb more heat (royal blue for example) and lighter blues will absorb less heat (baby blue). A general rule of thumb is: the darker the color, the more heat that color will absorb. So, on a hot day, make sure to wear light-colored clothing to stay as cool as possible! Thanks for the great question! Answer 2: Good question! If an object is not totally transparent or reflective, then it is capable of absorbing energy in the form of light or heat. If something is blue, that means it absorbs all frequencies of visible light except blue (450 nanometer wavelength) light which is reflected or transmitted through. Usually objects which absorb all this light as energy have no way of converting that energy except by reducing it to heat in the form of vibrations which increase its temperature. Some materials can emit light back, and this is called fluorescence. Other materials can potentially generate electricity through charge, and these materials would make good solar cells. Answer 3: The color blue does absorb heat. In general, the more light an object absorbs, the more heat absorbed since light is energy. Black absorbs the most heat. A black object absorbs all wavelengths of light and reflects none. Objects that are white, on the other hand, reflect all wavelengths of light and therefore absorb the least heat. Comparing other colors is difficult, as the color we see is a complicated mixture of the light that is reflected back to our eyes (not absorbed). But in general, the darker the color, the more light and heat absorbed. This is an answer already stored on our database: When an object appears a certain color when illuminated by white light it means that it is reflecting light of that color and absorbing all other colors. For example, a red apple is reflecting red light and absorbing all other colors of light. The more light the object absorbs, the more heat absorbed since light is energy. If you consider it a color, black absorbs the most heat. A black object absorbs all wavelengths of light and reflects none. Objects that are white, on the other hand, reflect all wavelengths of light and therefore absorb the least heat. Answer 4: When you look at an object and you see that it has a color, what you are seeing is the light that gets reflected off the object and gets detected by your eyes. This means that every other wavelength of light in the visible spectrum is absorbed. When light is absorbed, it can get converted into heat. Therefore, a blue object will absorb visible light which is not blue, and convert it into heat. Additionally, even if you had an object which appeared white (or another color for that matter), it may still be absorbing ultraviolet or infrared light which would then also be converted to heat. Answer 5: All colors absorb heat. Blue things absorb light that isn't blue. Answer 6: The fact that a material appears blue means that the material is absorbing some colours of light (likely orange). Because energy is conserved, if the material is absorbing light, it is likely being converted into heat. For example, if you did a careful experiment where you had a bright orange light and shined it on a piece of blue paper and a piece of white paper, the white paper reflects more light, so it absorbs less energy from visible and near-visible light. Because the white paper absorbs less energy, you would expect it wouldn't get as hot as the blue piece of paper. Answer 7: White light, from the sun or a light bulb, is made up of electromagnetic waves of every color at once, including "colors" of light that we can't see. Objects that appear blue do so because they reflect blue light but absorb all other colors, so our eyes only see the blue light remaining. When a blue object absorbs the energy from non-blue light, it heats up. Oftentimes when people talk about heat they are referring to infrared radiation. Infrared radiation is just like light of a color that we can't see, it's a form of electromagnetic radiation. If we could see infrared light, it would be the color that comes before red in a rainbow: infrared, red, orange, yellow, green, blue, purple. People think of infrared radiation as heat because hot objects give off more infrared radiation than visible light. An object needs to reach several thousand degrees (like the sun) in order to give off more visible light than infrared. That's probably why we evolved to see the colors that we do - because the sun puts out most of its energy in that part of the electromagnetic spectrum. A blue object could absorb or reflect infrared radiation - it looks blue only in the visible color spectrum and that doesn't tell us anything for sure about what it does with infrared light. But most objects except for shiny metals will absorb at least some of the infrared radiation that hits them. So to summarize, blue objects will usually absorb heat. Click Here to return to the search form.

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