The Science of Fireworks

Washington, D.C. July 4th fireworks

It’s the sign that Fourth of July is right around the corner – fireworks. The light displays decorate the skies across the United States every year to celebrate our Independence Day. All of the beauty and marvel that comes with fireworks displays is actually due to science.

Chemistry is behind the vivid displays of fireworks in a few ways. The basic formula to create fireworks combines an oxygen rich chemical with burning fuel. Additional chemicals within the package can create the different colors seen in the displays. Strontium will create red colors, titanium causes white and copper produces fireworks with a blue tint. Blue is one of the more difficult colors to achieve because the copper needs to reach a certain temperature (after all, what’s Fourth of July without red white and blue?). Fireworks produce an exothermic reaction, which means that they release energy as heat. That heat turns into the lights and colors we see in the sky.

While chemistry is responsible for many processes during fireworks explosions, physics also plays its own role. The final height of the firework depends on its initial speed. Fireworks are launched using force from an explosion, accelerating it upward. Pressure causes the fireworks to fly upwards and eventually explode outward.

Hundreds of people are injured due to fireworks. Even the handheld sparklers can burn at a temperature of 2,000°F+. Those types of temperatures can melt certain metals, so it would do similar damage to skin.

Meteorology can also affect a fireworks show. Higher humidity may tone down the otherwise vivid colors that decorate the sky. Lightning could hit an unused firework and cause injuries to any bystanders. Strong winds pose a fire hazard – and drought makes things even more dangerous. Too little wind cannot clear smoke after the explosions. When the temperature increases with height (called an “inversion”) instead of decreasing as it usually does, smoke from the fireworks display could decrease viewing quality.

Eastern Iowans should prepare for isolated showers and storms for the afternoon and evening of Fourth of July 2018.

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Posted under Educational, Optics

This post was written by Rachael Peart on July 3, 2018

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