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Explaining the science behind fireworks displays

Why do fireworks look like they do and how does weather affect them

How fireworks work
How fireworks work (Copyright 2021 by WSLS 10 - All rights reserved.)

ROANOKE, Va. – It’s a tradition unlike any other: watching the fireworks on the 4th of July.

You’ve probably enjoyed a fireworks display or two in your life, but have you ever wondered how they work? Your Local Weather Authority is here to help!

Basically, a series of high-energy chemical compounds get mixed together inside of the casing of the firework. The combination causes an explosion of colors that you see in the night sky.

Elements like strontium, copper, calcium and sodium are at work here. They create red, blue, orange and yellow explosions, respectively.

There are other parts of the firework that serve merely to send the rocket far enough into the sky to be safe for spectators, including a fuse and a “motor” made of gunpowder.

It’s not just the firework itself that we have to think about. Weather can play a role in how these displays look, too!

Weather and fireworks: humidity, wind and drought (Copyright 2021 by WSLS 10 - All rights reserved.)

On low humidity days, the explosions will appear brighter than on days with more moisture in the air.

The wind plays a factor in where the embers or smoke from the explosions go.

We have to be especially careful during a drought when we shoot fireworks! The fire danger is increased in such scenarios, so it’s important to have water nearby to quell any blazes.

Weather and fireworks: temperature inversion, rain and storms and fog (Copyright 2021 by WSLS 10 - All rights reserved.)

A temperature inversion happens when it’s cooler at the surface and warmer aloft. We see this sometimes in our area due to the mountain influence.

If such an inversion is in place, you’ll see smoke from fireworks get trapped and also the sounds from the explosions enhanced. Fog can also trap the sounds of fireworks.

Officials that put on fireworks displays have to be mindful of the rain and storm forecast when planning a show.

If it’s just plain old rain/showers, you can still shoot fireworks. However, if thunderstorms will be around, it’s best to postpone due to the safety hazard (lightning, wind, hail, etc.).

We are still trying to iron out the forecast for Sunday evening, as there are some model differences with the timing of a front. Look for updates in the coming days on

I do want to use this space to remind you about one more thing before the fireworks on Sunday: protect your dogs!

Dogs and fireworks (Copyright 2021 by WSLS 10 - All rights reserved.)

Making loud noises in the days leading up to Independence Day can help condition the pups for the fireworks (be smart about it, of course).

You should keep them indoors if you will be within earshot of any fireworks displays. Make a safe place for them to sleep and wrap them up in blankets.

We are keeping up a list of fireworks displays that will be happening across the area this holiday weekend. We here at Your Local Weather Authority hope you enjoy and feel free to send your photos via Pin It.

About the Author:

Justin McKee presents the weather forecast on 10 News Saturday and Sunday mornings from 6 to 8 a.m. He also fills in for other meteorologists during the week.