Fire is a fascinating natural phenomenon. When staring at fire, people often find themselves getting lost in its beauty. On top of that, it has a variety of different colors, which only makes people more intrigued. But why are the colors of fire different?
The different colors of fire are based on a few factors; the burning material or fuel, the radiation from excited atoms after a chemical reaction, and the temperature of the fire.
Read below as we go into further detail about why fire is different colors, and the different factors that influence the color of fire.
Why Is Fire Different Colors?
Flame color is mostly determined by the chemicals present in the flame. It all depends on what’s on fire. What’s in the flame can also affect how hot it gets.
Thus, incandescence is responsible for the various hues of a flame: materials that have been heated to such a high temperature that they glow. When light is created in this manner, the color and brightness of the light are determined by the temperature.
The incandescence of particles explains the spectrum of flame colors ranging from red to bright white, but what about blue flames? We also need to take into account some other phenomena.
The term “luminescence” is used to describe this phenomenon. Various components produce different colors when put through the flame test. It’s also the reason fireworks have such vivid, unique colors.
When heated or subjected to chemical change, atoms, and molecules can “emit” radiation in various spectrum patterns. The atomic or molecular electronic structure determines these patterns. Temperature does not affect the colors seen in flames because spectral emissions cause them.
Therefore, the shade of blue that we observe at the center of a candle fire, in an alcohol fire, and in a neutral oxy-acetylene fire is caused by the spectral emissions of the molecules that are present in the flame.
For more information on why there are different fire colors, watch this video below:
Why materials burn different colors
The Various Fuels and the Colors They Represent
Following are some common materials and what colors they emit when burning.
- Wood, paper, and other carbon-based materials produce an orange-yellow-red blaze.
- Propane emits a blue flame with an orange wick.
- Copper sulfate emits a green flame when burned.
- Calcium emits an orange flame.
- Potassium chloride emits a purple flame when burned.
- Methanol has no apparent flame, but it is still burning.
Which Color of Fire is the Hottest?
If we consider the most prevalent kinds of fire, we will find that blue fire has the reputation of being the most intense color of fire. In order to better explain this, we will first build a list for you that includes the following sorts of fire:
- Red fire (the coldest): 600-800 degrees Celsius
- Bright cherry red fire: 800-1000 degrees Celsius
- Orange fire: 1000–1200 degrees Celsius
- Yellow fire: 1200-1400 degrees Celsius
- White fire: 1300-1500 degrees Celsius
- Blue fire: 1400-1650 degrees Celsius
Traditionally, blue flames have been considered the hottest, followed by white. Following that, the most prevalent colors seen in the majority of fires are yellow, orange, and red.
It’s worth noting that while blue is typically associated with cold and red with heat (as seen on taps, for example), the opposite is true for fire. The popularity of blue fires is also due to the fact that the term “blue flame” is widely used.
In reality, the hottest shade of fire is violet/purple. It has a high ignition temperature (about 3000 F, or 1,650 degrees Celsius). That’s a lot of heat, and it’s why a violet flame is commonly observed during welding and cutting.
Which Color of Fire is the Coldest?
A diffusion (incomplete combustion) flame will seem red at lower temperatures, shifting through orange, yellow, and white as its temperature rises, as shown by shifts in the black-body radiation spectrum. The closer a certain portion of the flame is to white on this scale, the higher its temperature.
Why is the Sun Yellow?
The sun is currently in the most stable phase of its life cycle. For its size and nature, it does emit the majority of its visible light in the blue-green range of the spectrum. However, the sun would appear pure and bright white from outside our environment.
Why? We can’t tell the difference between the amounts of different colors emitted by the sun since our eyes can’t process that amount of energy, and the other sections of the spectrum are emitted just as strongly.
Since our eyes are overwhelmed by the total amount of light energy, we cannot tell whether or not it is blueish-green in absolute terms.
Why not blue rather than blue-ish green? Bluer, or more inclined towards violet or ultraviolet, light from the sun would require a higher temperature. There are many colors displayed at higher temperatures, blue being one of them but not the hottest.
The blue flames we create require significantly lower temperatures than the sun, so why can’t the sun do that?
The sun runs on simple components like hydrogen and helium, but the gasses and materials we employ to create flames and fireworks of varying colors are made up of a wide variety of compounds and elements.
Hydrogen and other forms of helium require far higher temperatures than the sun to become pure blue, violet, or beyond due to their chemical characteristics when they are burned.
About that pure-white glow: In the additive color model, human eyes see the resulting mixture as white when all the visible wavelengths (colors) are mixed at roughly the same levels.
Tiny color pixels consisting of even tinier red, green, and blue lights provide the illusion of white. Since we can’t see each individual color pixel (unless we use a magnifying lens and zoom in! ), our eyes blend the light and see white.
So, why does the sun appear “yellow” to us on Earth? When you find yourself within our planet’s atmosphere, which is primarily composed of nitrogen and oxygen, it does an excellent job of dispersing the short wavelengths that are found in the blue and green spectra.
This makes our sky blue while the color scatters in the gasses within our atmosphere. Longer-wavelength colors like yellow and red are more visible.
Since the sun is traveling through the least amount of atmosphere during midday, that’s when it seems to be the brightest and whitest. During sunrise and sunset, when the sun is at a low angle, more of the atmosphere blocks the blue and green light, leaving more of the orange and yellow spectrum.
Conclusion
Fire is indeed nature’s wonder. Now that you have all the information necessary to understand why fire has various colors, you can appreciate a flame’s different colors even more than before.
