What Happens When You Light a Fire?

There are few things more relaxing than snuggling up to a warm fire with a glass of wine, listening to the crackle, pop and sizzle as the flames dance. This is one of the most popular and effective methods for lowering blood pressure and improving moods. It also increases social interactions and helps you sleep better. In fact, a study found that watching a video of a fireplace actually decreased participants’ blood pressure!

But the leaping flames you’re observing aren’t just a pretty sight. They’re the result of a complex chemical reaction. And it’s the same kind of reaction that occurs when a cut apple turns brown, silver tarnishes and an iron nail rusts.

Fire is a natural process that has helped shape our planet for millions of years. The ancient Greeks even thought that it was one of the four elements that comprised everything on Earth – along with water, air and earth. When humans began to control it and use it for cooking, warmth and defense, though, they changed its role in nature significantly. Logging and tilling the land, over-grazing by livestock, and spraying weeds with herbicides caused wildfires to occur in places and at times when they hadn’t before.

Now, we rely on fire to provide energy for a majority of the human population on Earth. In addition to burning fossil fuels like coal, oil and natural gas in our homes, we produce electricity by igniting them in nuclear, hydroelectric or wind power stations. Many people also travel in vehicles with internal combustion engines that are powered by that same process.

While a majority of people enjoy the comforts and convenience of fire, others have embraced its destructive nature. Forest fires are a key part of the natural ecosystem, helping to clear the land for new growth and providing nutrients to the soil through smoldering debris. Wildfires also help to kill diseases and insects that can otherwise choke out the growth of healthy trees and plants.

In its simplest form, fire is a process of oxidation that transforms fuel and oxygen into carbon dioxide and water, producing heat in the process. But it is far more complicated than that. As the flames dance, they break apart the molecules of the fuel through a process called conduction. This in turn causes more fuel to ignite and the cycle to continue.

Some species of wildlife actually depend on wildfires to reproduce. For example, the White Stork and several types of beetle seek out smoldering tree trunks in which to lay their eggs. And a variety of other animals benefit from periodic wildfires, too. For instance, they remove dead organic material that would otherwise block worms and other organisms from the soil and slow down the return of nutrients to the soil. This makes the land more fertile. And the ashes left behind by the fire help to suppress weeds and insects that would otherwise compete with the newly sprouting vegetation.