What’s today’s temperature where you live? The rising and falling of temperatures affects many parts of life. Warm days might welcome you outside to play a game with friends. Humid or rainy afternoons make this more difficult. Cold, snowy days can provide their own sort of fun! 

Did you know temperature can even change the speed of sound? It’s true! Are you WONDERing how? Let’s start by talking about what sound is. Sound waves are made by vibrations. The waves can’t travel through a vacuum—they rely on the molecules of any given medium. These molecules carry sound waves from their source to your ears!

What does temperature have to do with this? You may have learned a bit about this topic in school. Heat is a form of energy—the faster a medium’s molecules move, the higher its temperature is. When these molecules move slower, the temperature cools.

Look around you. Everything you see is made from molecules: computer screens, house plants, pieces of paper, and even your own body! The air you’re breathing also contains molecules. The temperature outside on any given day is determined by the speed of air molecules.

On warm days, air molecules move faster. That means they also carry sound waves faster, increasing the speed of sounds. Can you guess what happens on the coldest winter days? If you think sound travels slower, you’re right! Air molecules move at a slower pace when the temperature is cold, so they carry sound waves at a slower pace as well.

Of course, speed isn’t everything. Have you ever noticed that you’re able to hear sounds from farther away on cold days? It’s not just your imagination! While sound moves faster in warm air, it doesn’t travel as far as it does in colder temperatures.

Temperature isn’t the only thing that affects the speed of sound. For instance, humidity also has an impact. By making air less dense, low humidity helps sound waves move faster. Air pressure can also make a difference.

The next time you’re looking for a fun outdoor activity, try experimenting with sound. Note the air temperature, and then invite some friends to help you see how far and fast different sounds can carry. Have fun learning more about how sound waves travel!